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General Anaesthesia (GA): Full Notes

Premedication, Induction, and Maintenance

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PART 1 - PREMEDICATION

Definition

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Goals / Aims of Premedication

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Drug Classes Used in Premedication

1. Benzodiazepines (most commonly used)

• Midazolam - most commonly used; water-soluble, short-acting, anxiolytic + amnesic
• Diazepam - longer acting, oral
• Lorazepam - potent, long-acting amnesic
• "White-coat" hypertension often resolves after an anxiolytic like midazolam - Bailey and Love's / Morgan & Mikhail

2. Anticholinergics

• Atropine - reduces secretions, prevents vagally-mediated bradycardia (especially in children)
  • Dosage (Pye's Surgical Handicraft):
    • Up to 2.5 kg: 0.15 mg
    • 2.5-8 kg: 0.2 mg
    • 8-15 kg: 0.3 mg i.m. 45 min before operation
    • 15-20 kg: 0.4 mg
    • Over 20 kg: 0.5 mg
• Hyoscine (scopolamine) - stronger antisialogogue, also antiemetic, causes sedation/amnesia
• Glycopyrrolate - does not cross blood-brain barrier (preferred in some situations)

3. Opioids

• Papaveretum + Hyoscine (older children/adults): Papaveretum 0.4 mg/kg + Hyoscine 0.008 mg/kg i.m. 1.5 h before operation. Max dose papaveretum 15 mg
• Pethidine Compound Injection (children): 0.06-0.08 ml/kg 1 h before operation (pethidine 25 mg + promethazine 6.25 mg + chlorpromazine 6.25 mg per ml)
• Morphine - also used in adults

4. Trimeprazine (Vallergan)

• Oral route only: 2-4 mg/kg, 2 hours before operation
• Used in small children

5. H2-blockers / Proton Pump Inhibitors

• Ranitidine, omeprazole - reduce gastric acid (aspiration prophylaxis)

6. Antiemetics

• Ondansetron, metoclopramide, dexamethasone

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Routine Premedication Regimens by Age Group (Pye's)

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Contraindications / Cautions for Premedication

• Sedatives contraindicated in neurosurgical patients and those with raised ICP
• Sedatives contraindicated when upper airway obstruction is present or anticipated
• Caution in elderly (respiratory depression), hepatic/renal impairment, and obese patients

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PART 2 - INDUCTION OF GA

Definition of GA

1. Unconsciousness (Amnesia) - loss of awareness
2. Analgesia - pain relief
3. Muscle relaxation

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Methods of Induction

A. Intravenous (IV) Induction - Most Common

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IV Induction Agents

Remember: Ketamine - emergence delirium is a key side effect. Co-administer benzodiazepine to reduce this.

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B. Inhalational Induction

• Used in:
  • Children (avoiding needle)
  • Needle-phobic adults
  • Patients with anticipated difficult airway (maintain spontaneous breathing)
• Agent: Sevoflurane is preferred (non-pungent, well tolerated)
• Higher risk of airway obstruction during inhalational induction

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Rapid Sequence Induction (RSI)

1. Pre-oxygenation (3-5 min with 100% O₂)
2. Apply cricoid pressure (Sellick's manoeuvre)
3. Pre-calculated dose of IV induction agent (propofol or thiopentone)
4. Immediately follow with suxamethonium (1-2 mg/kg) OR rocuronium (1.2 mg/kg) for rapid intubation
5. Intubate and confirm placement BEFORE releasing cricoid pressure
6. Inflate cuff of endotracheal tube

Suxamethonium: depolarising muscle relaxant - fastest onset, shortest duration. Risks: hyperkalaemia, malignant hyperthermia, muscle pain, prolonged apnoea. Rocuronium + Sugammadex: increasingly used as an alternative to suxamethonium in RSI - rocuronium provides rapid intubating conditions and sugammadex allows rapid reversal.

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Airway Management at Induction

• Failed intubation
• Accidental bronchial intubation (right main bronchus most common)
• Trauma to teeth, pharynx, larynx
• Aspiration of gastric contents
• Tube disconnection, kinking, or blockage
• Delayed tracheal stenosis

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PART 3 - MAINTENANCE OF GA

Methods of Maintenance

1. Inhalational agents (volatile anaesthetics)
2. Total Intravenous Anaesthesia (TIVA)
3. Balanced anaesthesia (combination of inhalational + IV agents)

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1. Inhalational (Volatile) Agents

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2. Total Intravenous Anaesthesia (TIVA)

• Propofol continuous infusion ± Remifentanil (ultra-short-acting opioid)
• Advantages:
  • No cumulative effect
  • Better haemodynamic stability
  • Excellent recovery profile (less PONV)
  • No environmental pollution from volatile agents
• Uses: Neurosurgery, airway laser surgery, cardiopulmonary bypass, day case surgery (Bailey and Love's)

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3. Balanced Anaesthesia

• Hypnotic (volatile or propofol)
• Opioid (fentanyl, remifentanil, alfentanil)
• Neuromuscular blocking agent
• Regional / local anaesthesia

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Muscle Relaxants in Maintenance

• Suxamethonium - quick onset, very short duration; ideal for rapid intubation and short procedures; adverse effects: muscle pain, hyperkalaemia, prolonged apnoea, malignant hyperthermia, anaphylaxis

• Neostigmine (acetylcholinesterase inhibitor) + glycopyrrolate (to prevent cholinergic side effects)
• Sugammadex - encapsulates rocuronium/vecuronium; complete rapid reversal; preferred over neostigmine

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Ventilation During Maintenance

• Volume-controlled ventilation: preset tidal volume delivered; pressure is variable - risk of barotrauma in obese, laparoscopic (Trendelenburg), and lung disease patients
• Pressure-controlled ventilation: preset pressure; tidal volume is variable; dependent on compliance and resistance
• Patients on NMBAs require mechanical ventilation (cannot breathe spontaneously)

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Monitoring During GA

• Pulse oximetry (SpO₂)
• Capnography (end-tidal CO₂) - confirms correct ETT placement, detects disconnection
• ECG - arrhythmias, ischaemia
• Non-invasive blood pressure (NIBP) - at minimum every 5 min
• Temperature - especially in children (malignant hyperthermia risk)
• Peripheral nerve stimulator - if NMBAs used
• Depth of anaesthesia monitors (BIS, entropy) - reduce awareness under GA

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Short-Acting Agents Preferred for Day Surgery

• Use of long-acting opioids like morphine is discouraged in day cases (delayed recovery, increased nausea/vomiting)
• Prefer propofol + remifentanil (TIVA) or sevoflurane/desflurane for rapid recovery
• Include multimodal analgesia and antiemesis in perioperative plan (Bailey and Love's)

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SUMMARY TABLE

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Tricks & Mnemonics for General Anaesthesia

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PART 1 - PREMEDICATION MNEMONICS

Goals of Premedication → "A SAGE"

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Anticholinergic drugs → "A He Got"

• Atropine
• Hyoscine
• Glycopyrrolate

Trick: Glycopyrrolate = "Glico stays outside" - it does NOT cross the blood-brain barrier (quaternary ammonium compound) → no CNS effects → preferred when sedation is unwanted

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When to give Atropine ONLY (no sedation) → "NAH"

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Age-based premedication quick trick:

"Infants = Atropine Alone" "Small kids = Atropine + Sedate" "Older kids = Benzo or Papaveretum + Hyoscine"

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PART 2 - GA TRIAD MNEMONIC

The Triad of GA → "AAM"

Alternative: "I Am Relaxed"

• Immobility/unconsciousness
• Analgesia
• Relaxation (muscle)

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PART 3 - IV INDUCTION AGENTS

Remember all 4 IV induction agents → "PEEK"

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Key property trick for each agent:

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Ketamine side effects → "HIDE"

Trick: Ketamine is the ONLY induction agent that maintains blood pressure and preserves respiratory drive → use it in trauma/field anaesthesia and haemodynamically unstable patients.

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Etomidate trick - "The Safe Heart Drug with One Problem"

Safe: Haemodynamically stable → use in cardiac patients Problem: "Etosteroidate" → it's a steroid derivative → blocks 11-β hydroxylase → adrenal suppression → avoid for prolonged infusion or repeat doses in ICU/sepsis

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PART 4 - INHALATIONAL AGENTS

Volatile agents → "SIDE"

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Quick property trick - Speed of onset/offset:

"Des > Sevo > Iso" (Desflurane fastest, Isoflurane slowest) Because: blood-gas solubility coefficient determines speed Low solubility = fast in, fast out Des (0.42) < Sevo (0.65) < Iso (1.4) - Lower number = faster

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Why Nitrous Oxide is declining → "MEGA"

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Nitrous oxide contraindications → "PENS"

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PART 5 - RAPID SEQUENCE INDUCTION (RSI)

Steps of RSI → "STOPP"

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RSI drug choice trick:

"SUX for RSI, SUGar reverses Roc"

• Suxamethonium = classic RSI drug (fastest onset)
• Sugammadex reverses Rocuronium rapidly if you can't intubate - "can't intubate, can't oxygenate" rescue plan

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PART 6 - MUSCLE RELAXANTS

NMBAs - remember them by duration → "SIR PA"

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Suxamethonium side effects → "MaHPHK" (Mah-Funk)

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Atracurium trick - "The Safe Relaxant in Failure"

"Atracurium doesn't care about your liver or kidneys" Hofmann degradation = spontaneous breakdown at body pH and temperature - no organ dependence → Use in renal AND hepatic failure

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Reversal agents trick:

"Neo needs company, Sugar works alone"

• Neostigmine must always be paired with glycopyrrolate (to block muscarinic side effects - bradycardia, secretions)
• Sugammadex works alone, reverses Rocuronium/Vecuronium completely and rapidly

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PART 7 - AIRWAY DEVICES

LMA generations trick:

"First gen = simple, Second gen = safer"

• 1st gen: Classic LMA (no gastric drain, low pressure seal)
• 2nd gen: ProSeal, i-gel (gastric drain tube + bite block + higher seal pressure)

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Complications of Intubation → "FATBAD"

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PART 8 - MONITORING

Standard monitoring during GA → "CAPETS"

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OVERALL QUICK RECALL FLOW

PREMEDICATION → INDUCTION → AIRWAY → MAINTENANCE → REVERSAL → EXTUBATION

"SAGE"          "PEEK"       "FATBAD"   "SIDE"        "Neo+Glyco    Confirm TOF
(goals)         (IV agents)  (avoid     (volatiles)    OR Sugammadex  = 4/4 twitches
                             complications) / TIVA              before extubate"

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These mnemonics cover every sub-topic in the GA notes. Pair each mnemonic with the underlying mechanism and you will retain the information far longer than rote memorization alone.

Medical Dictionary - General Anaesthesia Topic

Every Hard Word Explained Simply

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A

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Amnesia

• Pronunciation: am-NEE-zhuh
• Literal meaning: "without memory" (Greek: a = without, mnesis = memory)
• In GA context: The patient has NO memory of the surgery or what happened during anaesthesia. This is one of the three goals of GA (the first "A" in the triad AAM).
• Simple explanation: You go to sleep and wake up with zero memory of the operation - like a blank page.

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Anaesthesia / Anesthesia

• Pronunciation: an-es-THEE-zhuh
• Literal meaning: "without sensation" (Greek: an = without, aisthesis = sensation/feeling)
• Simple explanation: A medically induced state where you feel nothing - no pain, no awareness, no memory.
• Types: General (whole body unconscious), Regional (numb a region), Local (numb a small area)

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Anaesthetist / Anesthesiologist

• Who they are: The specialist doctor who administers anaesthesia, monitors the patient throughout surgery, and manages the airway, breathing, and circulation.
• Simple explanation: The "pilot" of the operation - keeps you safe while the surgeon does the job.

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Analgesic / Analgesia

• Pronunciation: an-al-JEE-zhuh
• Literal meaning: "without pain" (Greek: an = without, algos = pain)
• Simple explanation: Pain relief. Analgesics are pain-relieving drugs. Analgesia is the state of being pain-free.
• Examples in GA: Morphine, fentanyl, remifentanil, ketamine

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Anticholinergic

• Pronunciation: an-tee-koh-lin-ER-jik
• Literal meaning: Against (anti) + acetylcholine (the nerve chemical) + working (ergic)
• What it does: Blocks the effects of acetylcholine (a nerve chemical) on the body → reduces secretions, prevents slow heart rate, dries up saliva
• Simple explanation: "The drying drug" - dries your mouth, keeps heart rate up, prevents excessive secretions during surgery
• Examples: Atropine, hyoscine, glycopyrrolate

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Antisialogogue

• Pronunciation: an-tee-SY-al-oh-gog
• Literal meaning: Anti = against, sialon = saliva (Greek), agogos = leading
• Simple explanation: A drug that REDUCES saliva production. Very important during surgery to keep the airway dry and clear.
• Examples: Atropine, hyoscine, glycopyrrolate

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Anxiolytic

• Pronunciation: ang-zee-oh-LIT-ik
• Literal meaning: Anxietas = anxiety + lytic = dissolving/breaking down
• Simple explanation: An anti-anxiety drug. Given before surgery to calm the patient down and reduce fear.
• Examples: Midazolam, diazepam (benzodiazepines)

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Atracurium

• Type: Non-depolarising muscle relaxant (intermediate duration)
• Special feature: Undergoes Hofmann degradation - meaning it breaks down by itself in the blood without needing the liver or kidneys.
• Simple explanation: The "self-destructing" muscle relaxant - safe to use even in patients with kidney or liver failure.

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Atropine

• Origin: From the plant Atropa belladonna (deadly nightshade)
• Type: Anticholinergic drug
• What it does: Blocks muscarinic acetylcholine receptors → increases heart rate (vagolytic), reduces secretions (antisialogogue)
• Simple explanation: Speeds up the heart and dries up secretions. Used in premedication (especially in children and infants) and to treat bradycardia.

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B

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Balanced Anaesthesia

• Concept: Using a COMBINATION of different drugs, each targeting one component of the GA triad, instead of relying on one single drug at high doses.
• Components: Hypnotic (sleep) + Opioid (pain relief) + Muscle relaxant + Regional/local anaesthetic
• Simple explanation: "Don't put all your eggs in one basket." Multiple low-dose drugs together = better anaesthesia with fewer side effects than one high-dose drug.

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Barbiturate

• Pronunciation: bar-BIT-yur-ayt
• What it is: A class of drugs derived from barbituric acid
• In GA: Thiopentone (thiopental) is a barbiturate used for induction
• Mechanism: Acts on GABA-A receptors → depresses the CNS → causes unconsciousness
• Simple explanation: An old sleeping/sedating drug class. Thiopentone is used to make you unconscious at induction.

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Benzodiazepine

• Pronunciation: ben-zoh-dy-AZ-eh-peen
• What it is: A class of drugs that enhance the effect of GABA (the brain's natural calming chemical)
• Effects: Anxiolysis, sedation, amnesia, anticonvulsant, muscle relaxation
• Examples: Midazolam, diazepam, lorazepam
• Simple explanation: The "calm-down" drug class - reduces anxiety, helps you forget, makes you sleepy.

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BIS (Bispectral Index)

• What it is: A number (0-100) derived from brain wave (EEG) analysis that tells the anaesthetist HOW DEEP the anaesthesia is.
  • 100 = fully awake
  • 40-60 = ideal anaesthetic depth for surgery
  • 0 = flat line (no brain activity)
• Simple explanation: A "depth meter" for sleep during GA - prevents the patient from being too awake (awareness) or too deep.

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C

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Capnography

• Pronunciation: kap-NOG-rah-fee
• Literal meaning: Kapnos = smoke/CO₂ (Greek) + graphy = recording
• What it does: Measures the amount of CO₂ in exhaled breath (end-tidal CO₂ / EtCO₂)
• Why important: Confirms the breathing tube is in the correct place (trachea, not oesophagus); monitors breathing adequacy
• Simple explanation: "The breathing checker" - a graph that shows every breath the patient takes by measuring the CO₂ they exhale.

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Cricoid Pressure (Sellick's Manoeuvre)

• What it is: Manual pressure applied downward on the cricoid cartilage (a ring-shaped cartilage in the neck, below the thyroid cartilage)
• Purpose: Compresses the oesophagus against the vertebral spine → prevents stomach contents from coming up and entering the lungs during RSI
• Named after: Dr Brian Sellick (1961)
• Simple explanation: "Blocking the food pipe" - pressing on the throat to stop vomit from entering the airways when putting in a breathing tube in emergency situations.

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Curare

• What it is: A plant-based poison used by South American indigenous tribes on arrows; introduced into anaesthesia in 1942 by Griffith and Johnson
• Significance: The FIRST neuromuscular blocking agent used in anaesthesia - a landmark moment. Allowed muscle relaxation without needing dangerously deep anaesthesia.
• Simple explanation: The "arrow poison" that revolutionised surgery by making muscle relaxation safe.

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D

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Depolarising Muscle Relaxant

• What it means: A muscle relaxant that works by ATTACHING to acetylcholine receptors and ACTIVATING them (depolarising = causing the muscle to fire), causing an initial twitch (fasciculations), then prolonged relaxation.
• Only example in clinical use: Suxamethonium (succinylcholine)
• Key feature: Rapid onset, very short duration
• Simple explanation: "Fires first, then relaxes" - causes a brief muscle twitch (you see the patient's body twitch all over), then relaxes completely. Opposite of non-depolarising.

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Desflurane

• Type: Volatile (inhalational) anaesthetic agent
• Key property: Lowest blood-gas solubility coefficient (0.42) = fastest onset AND fastest offset of all volatiles
• Problem: Very pungent (irritating to airways) - cannot be used for inhalational induction
• Simple explanation: "The fastest in, fastest out" anaesthetic gas - great for quick recovery but too irritating to breathe in while you're awake.

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Dissociative Anaesthesia

• What it means: A unique state produced by ketamine where the patient is "disconnected" from their environment - they appear awake (eyes may be open) but feel no pain and have no memory
• Mechanism: Ketamine blocks NMDA receptors in the brain → dissociates sensory input from consciousness
• Simple explanation: A trance-like state - you're technically "awake" (heart beating, breathing, eyes open) but completely cut off from feeling or responding to pain.

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E

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EMLA Cream

• Stands for: Eutectic Mixture of Local Anaesthetics
• What it contains: Lignocaine + Prilocaine
• How it works: Applied under an airtight dressing on the skin 1 hour before a needle procedure → numbs the skin locally
• Use in GA: Applied to a child's hand 1 hour before surgery so the IV cannula insertion doesn't hurt → reduces distress at induction
• Simple explanation: "Numbing cream" - makes the skin pain-free so the needle for the drip doesn't cause pain or crying.

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Emergence Delirium

• What it is: A state of confusion, agitation, crying, disorientation that can occur as a patient wakes up (emerges) from anaesthesia
• Most associated with: Ketamine (in adults), Sevoflurane (in children)
• Simple explanation: "Waking up confused and upset" - the patient comes round from anaesthesia in a disturbed, frightened or combative state. Benzodiazepines are given with ketamine to reduce this.

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Etomidate

• Type: IV induction agent (steroid derivative / carboxylated imidazole)
• Key property: The most haemodynamically stable induction agent - least effect on blood pressure and heart
• Big problem: Even a SINGLE dose suppresses the adrenal cortex (adrenocortical suppression) by blocking the enzyme 11-β hydroxylase → cannot make cortisol
• Use: Ideal for sick patients, cardiac patients, haemodynamically unstable patients
• Simple explanation: "Gentle on the heart, mean to the adrenal gland."

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Extubation

• What it means: Removal of the endotracheal tube (breathing tube) from the trachea at the END of surgery, when the patient can breathe on their own
• Requirements before extubation: Patient awake enough, muscle relaxation fully reversed (confirmed by TOF), adequate spontaneous breathing
• Simple explanation: "Taking out the breathing tube" when surgery is done and the patient is waking up.

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F

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Fasciculations

• Pronunciation: fah-sik-yoo-LAY-shunz
• What they are: Brief, involuntary, random muscle twitches visible all over the body
• When they occur: After suxamethonium injection (because it depolarises all muscle fibres briefly before causing relaxation)
• Why it matters: These fasciculations cause post-operative muscle pains (myalgia)
• Simple explanation: The full-body "jiggle" you see briefly after giving suxamethonium - every muscle fires at once for a second, then goes floppy.

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Fentanyl

• Type: Synthetic opioid (100× more potent than morphine)
• Use in GA: Intraoperative analgesia; given during maintenance; can be given as bolus or infusion
• Simple explanation: A very powerful, fast-acting painkiller used during surgery to prevent the body reacting to the surgical pain.

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Fibreoptic Intubation (Fibreoptic Bronchoscope)

• What it is: A thin, flexible tube with a camera and light at the tip used to visualise the airway and guide an endotracheal tube into the trachea under direct vision
• When used: Anticipated or known difficult airway; can be done awake with topical local anaesthetic
• Simple explanation: "The flexible camera in the throat" - guides the breathing tube in patients whose airways are hard to access normally.

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G

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GABA (Gamma-Aminobutyric Acid)

• What it is: The main INHIBITORY neurotransmitter in the brain - it "calms" or "slows down" nerve activity
• Relevance to GA: Most anaesthetic agents (propofol, thiopentone, benzodiazepines, volatile agents) work by ENHANCING GABA activity → brain activity is suppressed → unconsciousness
• Simple explanation: The brain's natural "calm down" chemical. Anaesthetics amplify its effect to produce sleep/unconsciousness.

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Glycopyrrolate

• Type: Anticholinergic drug (quaternary ammonium compound)
• Key feature: Does NOT cross the blood-brain barrier (unlike atropine and hyoscine)
• Uses: Reduces secretions; given with neostigmine to prevent bradycardia/excessive secretions
• Simple explanation: "The body-only drying drug" - works only in the body (heart, glands) without affecting the brain. Safer option when brain effects are undesired.

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H

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Hofmann Degradation

• What it means: A process of spontaneous breakdown/elimination of a drug at normal body temperature and pH - WITHOUT needing the liver or kidneys
• Drug that uses this: Atracurium (and cisatracurium)
• Clinical importance: Safe to use in patients with kidney failure or liver failure because the body doesn't need functioning organs to eliminate the drug
• Simple explanation: "Self-destructing" - the drug breaks itself down automatically in the bloodstream. No organ needed.

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Hyperkalaemia

• Pronunciation: hy-per-kah-LEE-mee-ah
• Literal meaning: Hyper = high, kali = potassium (Latin), aemia = in blood
• What it means: Abnormally HIGH levels of potassium in the blood
• In GA context: Suxamethonium can cause dangerous hyperkalaemia (especially in burns, crush injuries, denervation injuries, prolonged bed rest)
• Why dangerous: High potassium causes life-threatening cardiac arrhythmias (including cardiac arrest)
• Simple explanation: "Too much potassium in the blood" - can stop the heart. A serious side effect of suxamethonium in certain patients.

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Hyoscine (Scopolamine)

• Type: Anticholinergic drug
• Special features compared to atropine: More sedating, stronger antisialogogue, better antiemetic, causes amnesia; crosses blood-brain barrier
• Simple explanation: "Atropine's sedating cousin" - dries secretions AND makes you drowsy and forgetful.

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I

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Induction

• What it means: The BEGINNING phase of anaesthesia - the process of taking the patient from consciousness to unconsciousness
• Simple explanation: "Going under" - the part where the drugs kick in and the patient falls asleep for surgery.

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Intubation (Endotracheal Intubation)

• What it means: Passing an endotracheal tube (ETT) through the mouth (or nose) → through the vocal cords → into the TRACHEA (windpipe)
• Purpose: Secure the airway, enable mechanical ventilation, prevent aspiration
• Simple explanation: "Putting a breathing tube in the throat" - the gold standard for securing the airway during GA.

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Isoflurane

• Type: Volatile (inhalational) anaesthetic agent
• Properties: Pungent (moderately), stable cardiovascular profile, coronary vasodilator
• Blood-gas solubility: 1.4 (higher than sevo and des = slower onset/offset)
• Simple explanation: An older volatile agent - reliable but slower to wear off than newer agents.

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K

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Ketamine

• Type: IV induction agent; NMDA receptor antagonist; phencyclidine derivative
• Unique properties: Produces dissociative anaesthesia, MAINTAINS blood pressure and respiratory drive (sympathomimetic), powerful analgesic, bronchodilator
• Side effects: Emergence delirium, hallucinations, increased ICP, increased IOP, hypersalivation
• Ideal for: Haemodynamically unstable patients, trauma/field anaesthesia, asthmatic patients (bronchodilator)
• Simple explanation: "The soldier's anaesthetic" - keeps BP up and breathing going. Used in battlefields, emergency rooms, and children.

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L

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Laryngeal Mask Airway (LMA)

• What it is: A supraglottic airway device - a mask with an inflatable cuff that sits ABOVE the vocal cords (at the glottis), providing a seal for ventilation
• Invented by: Dr Archie Brain (UK)
• Generations:
  • 1st gen (Classic LMA) - basic, no gastric drain
  • 2nd gen (ProSeal, i-gel) - gastric drain tube, higher pressure seal, bite block
• Simple explanation: "The mask in the throat" - less invasive than an ETT; placed in the back of the mouth and sits over the airway like a mask.

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Laryngoscopy

• What it means: Direct visualisation of the larynx (voice box) using a laryngoscope (rigid metal device with a light and blade)
• Purpose: To see the vocal cords and guide the ETT through them
• Simple explanation: "Looking in the throat with a special torch/blade" to see the vocal cords and pass the breathing tube.

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M

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MAC (Minimum Alveolar Concentration)

• What it means: The concentration of a volatile anaesthetic (in the alveoli of the lungs) at which 50% of patients do NOT move in response to a surgical stimulus (skin incision)
• Measured in: % at 1 atmosphere pressure
• Use: Tells you the POTENCY of a volatile agent. Lower MAC = more potent.
  • Isoflurane MAC = 1.17%
  • Sevoflurane MAC = 2.05%
  • Desflurane MAC = 6.6%
  • Nitrous oxide MAC = 104% (needs hyperbaric conditions - practically NOT a complete anaesthetic alone)
• Simple explanation: "The 50/50 dose" - the concentration where half the patients would stay still for a cut. A standard way to compare how strong volatile agents are.

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Maintenance

• What it means: The ONGOING phase of anaesthesia DURING surgery - keeping the patient unconscious, pain-free, and relaxed after induction
• Simple explanation: "Staying asleep" - keeping anaesthesia going for the duration of the operation.

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Malignant Hyperthermia (MH)

• What it is: A rare, life-threatening genetic condition where certain anaesthetic triggers (suxamethonium, volatile agents) cause an uncontrolled increase in skeletal muscle metabolism → extreme fever (>40°C), muscle rigidity, lactic acidosis, tachycardia
• Genetic basis: Mutation in ryanodine receptor (RYR1 gene)
• Treatment: Dantrolene (the ONLY specific treatment) + cooling + supportive care
• Simple explanation: "The runaway muscle reaction" - muscles suddenly go into overdrive generating dangerous heat. A medical emergency.

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Midazolam

• Type: Benzodiazepine (water-soluble, short-acting)
• Uses: Premedication (most commonly used), procedural sedation, induction of GA, ICU sedation
• Key properties: Anxiolytic, amnesic, sedative, anticonvulsant
• Route: IV, IM, oral, intranasal
• Simple explanation: "The forget-me drug" - gives you amnesia and relaxation. Most popular premedication drug worldwide.

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Muscle Relaxant (Neuromuscular Blocking Agent / NMBA)

• What it does: Blocks the neuromuscular junction (the connection between nerve and muscle) → causes paralysis of ALL muscles including breathing muscles
• Implication: Patient CANNOT breathe → MUST be mechanically ventilated
• Simple explanation: "The paralysing drug" - stops all voluntary muscles from working. The patient must be put on a breathing machine.

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N

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Neostigmine

• Type: Anticholinesterase drug (reversal agent for non-depolarising NMBAs)
• Mechanism: Inhibits acetylcholinesterase enzyme → acetylcholine builds up at neuromuscular junction → competes with and overcomes the NMBA block
• Must be given with: Glycopyrrolate or atropine (to counteract muscarinic side effects: bradycardia, bronchospasm, increased secretions)
• Simple explanation: "The un-paralysing drug" - reverses muscle relaxation at end of surgery. Always paired with an anticholinergic to prevent dangerous heart slowing.

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Neuromuscular Junction (NMJ)

• What it is: The synapse (connection point) between a motor nerve ending and a muscle fibre
• How it works: Nerve releases acetylcholine → binds to nicotinic receptors on muscle → muscle contracts
• In GA: NMBAs block this junction → no signal gets through → no muscle contraction → paralysis
• Simple explanation: "The nerve-muscle handshake point" - where the nerve tells the muscle to move. NMBAs block this handshake.

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NMDA Receptor (N-Methyl-D-Aspartate)

• What it is: An excitatory receptor in the brain and spinal cord that responds to the neurotransmitter glutamate
• Role: Involved in pain processing, memory, and consciousness
• Relevance to GA: Ketamine blocks NMDA receptors → dissociative anaesthesia + analgesia
• Simple explanation: "The pain and memory receptor" - ketamine locks it so you feel no pain and make no memories.

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Nitrous Oxide (N₂O)

• Common name: Laughing gas
• Properties: Colourless, sweet-smelling gas; analgesic, weak anaesthetic, carrier gas
• MAC: 104% (cannot produce full anaesthesia on its own at normal pressures)
• Problems: PONV, expands gas-filled cavities, mutagenic, potent greenhouse gas
• Simple explanation: "Laughing gas" - reduces pain and causes mild euphoria but not strong enough to be used alone as an anaesthetic.

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Non-Depolarising Muscle Relaxant

• What it means: Works by COMPETITIVELY BLOCKING acetylcholine receptors at the NMJ WITHOUT activating them (no fasciculations, no initial twitch)
• Examples: Vecuronium, atracurium, rocuronium, pancuronium, cisatracurium
• Reversible with: Neostigmine or sugammadex
• Simple explanation: "The quiet blocker" - sits on the receptor and blocks it without firing it first. Longer duration than suxamethonium.

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O

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Opioid

• What it is: A class of drugs that act on opioid receptors (mu, kappa, delta) in the brain and spinal cord
• Effects: Analgesia, sedation, euphoria, respiratory depression, constipation, nausea
• Examples used in GA: Morphine, fentanyl, alfentanil, remifentanil, pethidine
• Simple explanation: "The strong painkiller class" - derived originally from the opium poppy. Powerful pain relief but can slow breathing.

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P

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Papaveretum

• What it is: A mixture of opium alkaloids (mainly morphine ~50%, with papaverine, codeine, noscapine)
• Use in GA: Premedication (given with hyoscine in older children/adults)
• Simple explanation: "Mixed opium extract" - a traditional opioid premedication given before surgery.

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Premedication

• What it means: Drugs given BEFORE anaesthesia is started, usually 30 min to 2 hours prior to the operation
• Purpose: Reduce anxiety, reduce secretions, provide pain relief, prevent aspiration, prevent PONV
• Simple explanation: "The prep drugs" - the medications given before you go to the operating theatre to make the whole experience safer and smoother.

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Propofol

• Type: IV induction agent AND maintenance agent (di-isopropyl phenol)
• Appearance: Milky white emulsion (looks like milk)
• Properties: Smooth induction, antiemetic, can be used as infusion for maintenance (TIVA), short duration
• Side effects: Pain on injection, hypotension, apnoea at induction
• Simple explanation: "The milk of anaesthesia" - the most commonly used anaesthetic drug in the world for putting patients to sleep.

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Pseudocholinesterase Deficiency

• What it is: A genetic condition where the enzyme that normally breaks down suxamethonium (pseudocholinesterase/plasma cholinesterase) is absent or abnormal
• Consequence: Suxamethonium is not broken down → prolonged paralysis and apnoea (hours instead of minutes)
• Simple explanation: "Can't break down the drug" - the patient stays paralysed and cannot breathe for much longer than expected after suxamethonium.

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R

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Rapid Sequence Induction (RSI)

• What it is: A specific, fast technique of inducing anaesthesia designed to minimise the time between loss of consciousness and securing the airway with an ETT, in patients at risk of aspirating stomach contents
• Key elements: Pre-oxygenation, cricoid pressure, fast-acting IV induction agent + rapid NMBA (suxamethonium or rocuronium), immediate intubation
• Simple explanation: "The emergency induction" - done in patients with a full stomach where vomiting during induction could be fatal.

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Remifentanil

• Type: Ultra-short-acting synthetic opioid
• Key property: Metabolised by blood and tissue esterases (not by liver) → context-insensitive half-life → wears off in minutes regardless of infusion duration
• Use: TIVA (with propofol), infusion during maintenance
• Caution: Causes rapid, intense analgesia but pain returns suddenly at offset → must plan post-op analgesia
• Simple explanation: "The blink-and-it's-gone opioid" - powerful during surgery but disappears very quickly when the infusion stops.

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Rocuronium

• Type: Non-depolarising NMBA (intermediate duration, rapid onset)
• Special feature: Fastest onset among non-depolarising agents → can be used in RSI as alternative to suxamethonium
• Reversal: Reversed rapidly and completely with sugammadex
• Simple explanation: "The reversible RSI drug" - fast enough to use in emergencies AND can be completely reversed if intubation fails.

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S

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Sellick's Manoeuvre → See Cricoid Pressure above

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Sevoflurane

• Type: Volatile anaesthetic
• Properties: Non-pungent (pleasant smell), low blood-gas solubility (0.65) - fast onset/offset
• Uses: Inhalational induction (especially children), maintenance
• Side effects: Emergence agitation in children
• Simple explanation: "The sweet-smelling sleep gas" - preferred for mask inductions because it doesn't irritate the throat.

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Sugammadex

• Pronunciation: SOO-gah-mah-deks
• What it is: A modified gamma-cyclodextrin molecule that forms a tight "cage" around rocuronium (and vecuronium) molecules, trapping them and making them inactive
• Significance: Can reverse DEEP neuromuscular block within 3 minutes - something neostigmine cannot do
• Use in RSI: If rocuronium is used for RSI and intubation fails → give sugammadex → patient wakes up and can breathe again
• Simple explanation: "The drug-catcher" - acts like a microscopic cage that traps and neutralises the muscle relaxant instantly.

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Supraglottic Airway

• What it means: An airway device that sits ABOVE (supra = above) the glottis (vocal cords/opening of larynx)
• Examples: LMA (all types), i-gel, ProSeal
• Contrast with: Endotracheal tube which passes THROUGH the glottis into the trachea
• Simple explanation: "The throat device above the voicebox" - easier to insert than an ETT but does not fully protect against aspiration.

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Suxamethonium (Succinylcholine)

• Type: Depolarising NMBA
• Mechanism: Two acetylcholine molecules joined together → binds and persistently activates nicotinic receptors → depolarisation → fasciculations → then relaxation (because receptor stays open but cannot repolarise)
• Duration: Very short (3-5 min) - broken down by plasma pseudocholinesterase
• Use: RSI, short procedures requiring rapid intubation
• Simple explanation: "The fastest but trickiest muscle relaxant" - incredibly fast and short-acting, but has a long list of possible dangerous side effects.

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T

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Thiopentone (Thiopental)

• Type: Barbiturate IV induction agent
• Properties: Rapid induction (one arm-brain circulation time ~15-20 sec), reduces ICP and cerebral metabolic rate, causes myocardial depression and hypotension
• Context: Being replaced by propofol in most settings; still valuable in neurosurgery for brain protection
• Simple explanation: "The old reliable sleep drug" - fast but drops blood pressure. Still used in brain operations where reducing brain swelling matters.

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TIVA (Total Intravenous Anaesthesia)

• What it means: Maintaining anaesthesia entirely with IV drugs (NO inhalational/volatile agents)
• Standard regimen: Propofol infusion + Remifentanil infusion (± other adjuncts)
• Advantages: Less PONV, no pollution, better haemodynamic stability, faster recovery
• Uses: Neurosurgery, airway laser surgery, cardiopulmonary bypass, day case surgery
• Simple explanation: "All-in-the-drip anaesthesia" - the patient stays asleep entirely via the IV line, with no gas going into the lungs.

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TOF (Train-of-Four)

• What it is: A monitoring technique using a peripheral nerve stimulator to assess the degree of neuromuscular block
• How it works: Four electrical stimuli are delivered to a peripheral nerve (e.g. ulnar nerve at wrist) and the resulting muscle twitches are counted/measured
  • 0/4 twitches = deep block (cannot intubate safely without RSI agent; cannot extubate)
  • 4/4 twitches with good strength = adequate reversal → safe to extubate
• Simple explanation: "The four-twitch test" - counts how many muscle twitches occur to check if the paralysing drug has worn off enough for the patient to breathe safely.

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Trachea

• What it is: The windpipe - the cartilaginous tube running from the larynx (voice box) to the bronchi (main airways of the lungs)
• In GA: The endotracheal tube is placed INTO the trachea to maintain the airway and allow ventilation
• Simple explanation: "The windpipe" - the air highway between your throat and lungs.

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V

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Vagolytic

• Pronunciation: vay-goh-LIT-ik
• Literal meaning: Lytic = breaking/blocking + vagus = the vagus nerve
• What it means: Blocks the vagus nerve's effects → prevents vagally-mediated bradycardia (slow heart rate)
• Drugs: Atropine, hyoscine, glycopyrrolate
• Simple explanation: "The heart-rate protector" - prevents the heart from slowing down due to vagal stimulation (which can happen during laryngoscopy, intubation, or surgical manipulation).

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Vecuronium

• Type: Non-depolarising NMBA (long-acting)
• Properties: Minimal cardiovascular effects, less allergic reaction than other NMBAs
• Limitation: Depends on hepatic metabolism and renal clearance → use with caution in liver/kidney failure
• Reversed by: Neostigmine or sugammadex
• Simple explanation: "The heart-friendly muscle relaxant" - doesn't affect the cardiovascular system much, but be careful if the patient's liver or kidneys aren't working well.

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Volatile Agent

• What it means: An anaesthetic drug that exists as a liquid at room temperature but EVAPORATES easily into a vapour/gas that is inhaled
• Delivered via: The anaesthetic machine vaporiser
• Examples: Sevoflurane, isoflurane, desflurane
• Contrast with: Gases (nitrous oxide, oxygen) which are already in gas form
• Simple explanation: "The liquid-that-becomes-gas anaesthetic" - stored as liquid in a special container, turned into vapour by the machine, breathed in by the patient to maintain sleep.

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Quick Reference Index

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Every term above is from the context of the GA notes covered. Understanding these words as a "language" rather than isolated facts is what makes anaesthesia click as a subject.

Drug Name-Based Memory Tricks for General Anaesthesia

Every trick is built INTO the drug's name itself

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SECTION 1 - PREMEDICATION DRUGS

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🔵 MIDAZOLAM

"MID-azo-LAM = MID anxiety LAMination"

Visual trick: Think of a mildly sedated LAMB (LAM) standing MID-field. Calm, not sleeping. That's midazolam.

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🔵 DIAZEPAM

"DI-AZ-EPAM = DI(e) if you're AXious + EPAM(e) (escape)"

• DI = works on DIazepam receptors (BZD receptors named after it!)
• Longer acting than midazolam
• "Delay before surgery" - given 1-2 hours before

Trick: Diazepam = Days to clear from body (long half-life ~20-100 hours). Midazolam = Minutes to clear (short). D > M in duration.

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🔵 LORAZEPAM

"LOR-azepam = LORD of Amnesia"

Trick: LORazepam = Longest Onset but Really powerful Amnesia. "The Lord forgets everything."

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🔵 ATROPINE

"ATROPINE = ATRopin from ATrapa = A TRap for the vagus nerve"

Simple trick: ATROpine = Against + vaTRO (vagal tone) + PINE (it makes you dry like a pine tree - no moisture!)

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🔵 HYOSCINE (Scopolamine)

"HYO-scine = HYO(per) sedating + Scine (scene) of dryness"

• Hyoscine does everything atropine does PLUS:
  • PLUS sedation
  • PLUS amnesia
  • PLUS better antiemetic
  • PLUS crosses blood-brain barrier more readily

Trick: HYOSCINE = Higher sedation than atropine + Yields amnesia + Other features (antiemetic) + Strongest antisialogogue + Crosses BBB + Ideal for motion sickness (antiemetic) + Neurosurgery? No (causes sedation - avoid) + Excellent drying agent

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🔵 GLYCOPYRROLATE

"GLYCO-PYRRO-LATE = GLYCOgen doesn't cross, PYRROmid stays outside, LATE to the brain"

• GLYCO = "GLUED to the outside" - cannot cross the blood-brain barrier
• PYRRO = quaternary ammonium structure (think of a BARRIER/PYRAMID)
• LATE = LATEST anticholinergic, most selective

GLYcopyrrolate - GLYued outside (does not cross BBB) Atropine crosses → causes confusion in elderly Hyoscine crosses → causes sedation Glycopyrrolate stays → NO CNS effects → safest

"GLYCO carries NEO to safety" Neostigmine reverses muscle relaxation BUT causes muscarinic side effects (bradycardia, bronchospasm) Glycopyrrolate BLOCKS those side effects → "NEO does the job, GLYCO cleans up the mess"

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🔵 PROMETHAZINE

"PRO-METH-AZINE = PRO against nausea + METH(od) for sedation"

• Antihistamine (H1 blocker) with antiemetic + sedative effects
• Part of the Pethidine Compound injection (with pethidine + chlorpromazine)
• "PRO" = promotes sedation/antiemesis in paediatric premedication

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🔵 TRIMEPRAZINE (Alimemazine)

"TRIME-PRAZINE = TRIM the child's anxiety + PRAISE their calmness"

• Oral only: 2-4 mg/kg, 2 hours before surgery
• Phenothiazine antihistamine
• Only used in children (oral sedative premedication)

Trick: TRIME = Two hours before, Route is oral only, In children, Mild sedation, Effective anxiolysis

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SECTION 2 - IV INDUCTION AGENTS

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🔴 PROPOFOL

"PRO-PO-FOL = PROFessional, POwerful, FOLlows you home (short acting)"

• PROP = it PROPS you up against PONV (antiemetic - unique property!)
• OF = Oil-in-water emulsion - that's why it looks milky white
• FOL = FOLlows quick recovery - short acting

Visual trick: PROPOFOL looks like MILK. Think: "MILK OF AMNESIA" - white, smooth, puts you to sleep peacefully.

Side effect trick: "PROpofol = Pain + Hypotension + Apnoea + Bacteria risk (lipid medium - no preservative in some formulations)"

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🔴 THIOPENTONE (Thiopental)

"THIO-PEN-TONE = THIO(sulfur) PENcil TONES the brain down"

• THIO = contains SULPHUR atom (thio = sulfur in chemistry) → gives it the "rotten egg" smell when opened
• PENTO = pentobarbiturate (5-carbon barbiturate chain)
• TONE = tones DOWN the brain (↓ ICP, ↓ cerebral metabolic rate)

Big trick - THIO vs PROPOFOL:

• THIO - drops BP MORE, no antiemetic, can't maintain (redistributes)
• PROPOFOL - smoother, antiemetic, can maintain
• Choose THIO for neurosurgery (↓ICP), choose PROPOFOL for day surgery (antiemetic + TIVA)

Danger trick: "THIO is BASIC" - pH 10.8. If given into an artery by mistake → intense vasospasm + gangrene. "Thio outside = DISASTER."

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🔴 ETOMIDATE

"ETO-MID-ATE = ETO(my adrenal gland) ate the cortisol"

• ETO = sounds like "ATE-O" → it ATE your adrenal cortex's function
• MIDATE = "mid-stable" → haemodynamically mid/stable

THE ETOMIDATE TRICK: Split the name: "E-TO-MI-DATE"

• E = Excellent haemodynamics (most stable)
• TO = TOxic to adrenal gland (even one dose)
• MI = MInimal cardiovascular effects
• DATE = used in DATe (acute cardiac surgery/sick patients - the "date" = critical setting)

"Etomidate is the cardiologist's friend but the adrenal gland's enemy"

"Eto BLOCKS the BUILDER"

• 11-β hydroxylase builds cortisol from cholesterol
• Etomidate BLOCKS it → no cortisol → adrenal suppression
• "ETO = the enzyme-eating drug"

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🔴 KETAMINE

"KETA-MINE = KEY to a MINE (underground dissociation)"

• KETA = sounds like "KEY-TO" → the KEY TO maintaining BP and breathing
• MINE = goes into a MINE underground = dissociation (you're in a deep disconnected place)

The KETAMINE rule of opposites: Everything that other induction agents do, Ketamine does the OPPOSITE:

Other agents	Ketamine
Drop BP	Raises BP
Depress breathing	Preserves breathing
No analgesia	Profound analgesia
Antiemetic/neutral	Increases secretions
Reduce ICP	Raises ICP

Bronchospasm trick: "Ketamine = Keeps bronchi open" → Bronchodilator → drug of choice for asthmatic patients needing emergency anaesthesia

Emergence delirium prevention: "Give Ketamine with a Benzo → Keep the Bad dreams away"

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SECTION 3 - INHALATIONAL AGENTS

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🟢 SEVOFLURANE

"SEVO-FLU-RANE = SEVEN flowers RAINING gently"

• SEVO = sounds like "SOFT" or "SEVEN" → 7 letters, soft and gentle
• FLUR = FLUOR = fluorine atoms (fluorinated ether)
• ANE = ANaesthetic

The SEVO vs DESFLURANE speed trick:

• SEVO = Slower than Des but Smells Sweet → use for induction
• DES = DEStroys airway if given awake (pungent) but DEScends from body fastest

Sevo in children trick: "SEVO = SEVEN year olds LOVE it" - it's the go-to for paediatric inhalational induction because it smells pleasant.

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🟢 ISOFLURANE

"ISO-FLU-RANE = ISOlated FLUid in the RANE(rain) - takes time to wash out"

• ISO = ISOMER of enflurane (same atoms, different arrangement)
• ISO also = "SLOW" → it's the SLOWEST among clinical volatiles (blood-gas solubility 1.4)

Trick: "ISOflurane = ISOlated recovery room time" - takes LONGER to emerge because it's more soluble = more dissolves in blood = takes longer to breathe out.

Coronary steal trick: "ISOFLURANE = FLUte playing (coronary vasodilator)" → dilates coronary vessels → can cause coronary steal syndrome in coronary artery disease patients.

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🟢 DESFLURANE

"DES-FLU-RANE = DESert FLUshed RANEway (fastest exit)"

• DES = DESert → DESERT-DRY and extremely fast to evaporate = lowest blood-gas solubility (0.42)
• DES also = DEScent from anaesthesia fastest

The 3 volatiles speed order trick: "DES RACES, SEVO SKIPS, ISO WALKS"

• Des = fastest recovery
• Sevo = medium, safe for induction
• Iso = slowest

Desflurane storage trick: "DES needs a HEATED vaporiser (39°C)" because its boiling point is close to room temperature (23.5°C) → would boil unpredictably in normal vaporiser → needs special heated pressurised vaporiser

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🟢 NITROUS OXIDE (N₂O)

"NITROUS OXIDE = NICE TO USE but NOT OXIDE = NOT so great anymore"

• NITROUS = sounds like "NICE TO US" (historically - laughing gas, pleasant)
• OXIDE = "OX-SIDE" = the side that's going out of use (declining use)

The expanding gas trick: "N₂O = Not near gas ₂ = 2 times expansion possible in air spaces" N₂O diffuses INTO gas-filled cavities 34× faster than nitrogen diffuses out → the cavity expands → Contraindicated in: pneumothorax, middle ear surgery, eye surgery with intraocular gas, bowel obstruction

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SECTION 4 - MUSCLE RELAXANTS

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🟡 SUXAMETHONIUM (Succinylcholine)

"SUXA-METHON-IUM = SUXA(tion pump) = SUCKs you into paralysis fast"

• SUXA = sounds like SUCTION or SUCKS → SUCKs the strength out of muscles instantly
• METHON = two methyl groups (di-methyl, like two ACh joined together)
• IUM = positively charged (quaternary ammonium - cannot cross BBB)

The "Two ACh glued together" trick: Suxamethonium = literally TWO acetylcholine molecules stuck together → Binds ACh receptor and ACTIVATES it (unlike non-depolarising which just BLOCKS) → Initial activation = fasciculations → then stays stuck = no repolarisation = prolonged relaxation → Like pressing a doorbell and KEEPING YOUR FINGER ON IT - door stays alarmed (depolarised)

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🟡 ROCURONIUM

"ROCU-RON-IUM = ROCKET launch into paralysis quickly"

• ROCU = ROCKET = ROCket fast onset
• RON = sounds like "RUN" → muscles can't RUN away from it fast
• IUM = non-depolarising (can't cross BBB)

The ROCURONIUM - SUGAMMADEX pair trick: "ROCO and SUGAR are partners"

• ROCURONIUM = the paralysing rocket
• SUGAMMADEX = the cage that catches the rocket Together: "If you can't intubate, SUGAR reverses the ROCKET" = life-saving rescue plan

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🟡 VECURONIUM

"VECUR-ON-IUM = VEhiCle (no cargo) - carries NO cardiovascular baggage"

• VEC = VECtor/VEhiCle that carries no extra cargo (no histamine, no cardiovascular effects)
• URON = URON(e) = URiNe - partially eliminated by kidneys

Vecuronium vs Atracurium in organ failure:

• VEC = needs LIVER → avoid in liver failure
• ATR = Hofmann degradation → safe in ALL organ failure "VEC needs organs, ATR needs NOTHING"

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🟡 ATRACURIUM

"ATRA-CURIUM = ATTRITION of organs (no organ needed) + CURIUM (element that spontaneously decays)"

• ATRA = sounds like "EXTRA" → EXTRA safe (no organ dependence)
• CURIUM = named after Marie Curie → radioactive elements SPONTANEOUSLY decay → atracurium SPONTANEOUSLY degrades (Hofmann degradation!)

"HOFMANN = HOF means courtyard in German = breaks down in the open (blood) without needing to enter any organ house (liver/kidney)"

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🟡 CISATRACURIUM

"CIS-ATRA-CURIUM = CIS (pure form) of atracurium = LESS histamine, MORE pure"

• CIS = cis-isomer of atracurium = the clean, pure version
• CIS = sounds like "SISS" (hissing) = less histamine release (less hissing/wheezing)

Trick: CISatracurium = like CIStern water (cleaner, purer) vs ATRacurium (regular tap water). Same Hofmann breakdown, less histamine.

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🟡 PANCURONIUM

"PANCUR-ONIUM = PAN (all) + CURE = too much curing (long acting) + ONIUM (vagolytic)"

• PAN = Greek for ALL → ALL-day action (long acting, longest duration)
• PANCUR = PAN-CURE = cures all movements (longest paralysis)
• ON + IUM = vagolytic effect → causes tachycardia (blocks vagus)

Trick: "PANcuronium = PANcake that's heavy and STAYS on the plate (long duration) + makes the HEART RACE (tachycardia from vagolysis)"

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SECTION 5 - REVERSAL AGENTS

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🟣 NEOSTIGMINE

"NEO-STIG-MINE = NEW STIGMA on the cholinesterase enzyme (blocks it)"

• NEO = New (it's a synthetic version of physostigmine from Calabar bean)
• STIG = STIGma = marks/inhibits (inhibits cholinesterase)
• MINE = MINE the area = blocks the enzyme's active site

• Inhibits acetylcholinesterase → acetylcholine ACCUMULATES → overcomes the non-depolarising NMB block
• Like NEO in The Matrix: "He SAW what the enemy (NMB) was doing and OVERCAME it by multiplying his forces (ACh)"

"NEO needs a bodyguard trick": Neostigmine increases ACh EVERYWHERE - muscarinic effects:

• Bradycardia
• Bronchospasm
• Increased secretions → Glycopyrrolate or atropine given WITH neostigmine as bodyguard to block muscarinic side effects "NEO always brings GLYCO as a date"

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🟣 SUGAMMADEX

"SUGA-MM-ADEX = SUGAR CAGE that traps the drug"

• SUGA = SUGAR (it IS a modified sugar molecule - cyclodextrin = cyclic sugar)
• MM = Modified Molecule
• ADEX = ADDEX = adds to/traps the relaxant inside

SUGAR + GAMMADEX

• SUGAR = cyclodextrin sugar backbone
• GAMMA = γ-cyclodextrin ring shape (like a donut/cage)
• DEX = dextro = right-turning sugar

Sugammadex visual trick: Think of a PAC-MAN eating rocuronium. Once PAC-MAN swallows it, the drug is GONE - inactivated and excreted in urine as a complex.

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SECTION 6 - OPIOIDS IN GA

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🟠 FENTANYL

"FENT-ANYL = FAST entry into the brain (lipophilic)"

• FENT = FAST + phenENTanyl → FAST and potent
• ANYL = ANY pain? eliminated (100× more potent than morphine)

Trick: "FENTanyl = FENTastic pain relief, FENTastic speed" - most commonly used intraoperative opioid due to rapid onset.

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🟠 REMIFENTANIL

"REMI-FENTANIL = REMIND yourself it's GONE (ultra-short acting)"

• REMI = REMInd = you need to REMIND yourself it's still working because it disappears so fast
• FENTANIL = fentanyl family

"REMI = RAPID EXIT MIRACLE INFUSION"

• Context-insensitive half-life
• Broken down by PLASMA ESTERASES (not liver)
• Half-life = 3-5 minutes REGARDLESS of infusion duration
• Like sand in a timer - stops instantly when you flip it

The REMI trap trick: "REMI leaves the party first" When remifentanil infusion stops → pain returns SUDDENLY and INTENSELY → ALWAYS give long-acting opioid or regional block BEFORE ending TIVA/remifentanil

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🟠 MORPHINE

"MORPHINE = MORPHeus (God of Sleep) + FINE pain relief"

• MORPH = Morpheus, the Greek god of sleep and dreams
• INE = "IN E"very cancer/chronic pain protocol

Trick: "MORPHine = Morpheus puts you to Sleep, Opioid receptor agonist, Respiratory depression risk, Pain relief gold standard, High PONV risk, Itching (histamine), Nausea, Euphoria"

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🟠 PETHIDINE (Meperidine)

"PETHI-DINE = PET the pain away + DINE (last meal before surgery)"

• PETHI = PET = gentle opioid for mild-moderate pain
• DINE = like dining = it has local anaesthetic AND opioid properties (unique!)

Special feature trick: "PETHidine = the ONLY opioid with local anaesthetic properties" → used in spinal anaesthesia in some protocols

Danger trick: "PETHidine + MAO inhibitors = DEATH" - serotonin syndrome / fatal reaction. "PETH + MAO = NO GO"

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SECTION 7 - ANTICHOLINESTERASE (REVERSAL)

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🟣 PHYSOSTIGMINE

"PHYSO-STIG-MINE = PHYSIC (old word for medicine) + STIGMINE (mark the enzyme)"

• Only anticholinesterase that crosses BBB
• Used to reverse CNS anticholinergic effects (e.g., atropine overdose causing confusion)
• Trick: "PHYSOstigmine = PHYSIO for the BRAIN" (crosses blood-brain barrier unlike neostigmine)

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MASTER SUMMARY - NAME TRICK TABLE

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The best way to use these: Say the drug name aloud → the name itself tells you the story. Every drug was named with chemical or clinical clues baked in. Once you see the pattern, you stop memorising and start understanding.

Complete Medical Terminology Guide for General Anaesthesia

Every Confusing Word - Plain Language Explained

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HOW TO USE THIS GUIDE

When you are reading the GA notes and hit a word you don't understand - come here, find the word alphabetically, read the simple explanation, and go back to reading. This guide is built to REMOVE every reading block.

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A

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Acetylcholine (ACh)

• What it is: A chemical messenger (neurotransmitter) released by nerves to communicate with muscles and other organs
• Where it works:
  • Neuromuscular junction (nerve → muscle)
  • Heart (slows it down via vagus nerve)
  • Glands (increases secretions)
• Why it matters in GA: Muscle relaxants either MIMIC or BLOCK acetylcholine. Reversal agents increase it.
• Simple picture: Think of ACh as a KEY that fits into a LOCK (receptor) on the muscle and makes it contract. NMBAs block the lock. Neostigmine increases the number of keys available.

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Acetylcholinesterase

• What it is: The ENZYME (biological scissors) that BREAKS DOWN acetylcholine after it does its job
• Why it matters: After ACh triggers muscle contraction, this enzyme destroys it so the muscle can relax again
• In GA: Neostigmine INHIBITS this enzyme → ACh is NOT destroyed → it builds up → overcomes NMB block
• Simple picture: Acetylcholinesterase = the "cleaning crew" at the nerve-muscle junction. Neostigmine fires the cleaning crew → ACh piles up → muscle wakes up.

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Adrenocortical Suppression

• Broken down:
  • Adreno = adrenal gland
  • Cortical = cortex (outer layer) of the adrenal gland
  • Suppression = function is suppressed/reduced
• What it means: The outer layer of the adrenal gland stops making cortisol (the stress hormone)
• Caused by: Etomidate (even ONE dose)
• Why dangerous: Cortisol is essential for responding to surgical stress, infection, and maintaining blood pressure. Without it during surgery → haemodynamic instability, immunosuppression
• Simple picture: The adrenal gland is a factory that makes cortisol. Etomidate shuts the factory down temporarily. During surgery (a stressful time) you need the factory running.

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Adrenal Gland

• What it is: Two small glands sitting on TOP of each kidney
• What they make:
  • Cortex (outer): Cortisol, aldosterone, androgens
  • Medulla (inner): Adrenaline (epinephrine), noradrenaline
• Simple picture: A hat sitting on top of the kidney. The outer part makes stress hormones, the inner part makes the "fight or flight" chemicals.

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Adrenaline (Epinephrine)

• What it is: A hormone and neurotransmitter released during stress/fear ("fight or flight")
• Effects: Increases heart rate, raises blood pressure, dilates airways, increases blood sugar
• In GA context: Used in local anaesthetics to cause vasoconstriction (prolonging effect); used in anaphylaxis treatment
• Simple picture: The body's "alarm bell chemical" - fires when there's danger.

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Agonist

• What it means: A drug or chemical that BINDS to a receptor and ACTIVATES it (triggers a response)
• Opposite: Antagonist (binds but does NOT activate - blocks)
• Example in GA: Suxamethonium is an agonist at nicotinic ACh receptors - it binds AND activates them, causing depolarisation
• Simple picture: An agonist is a key that fits the lock AND opens the door. An antagonist is a fake key that fits but doesn't open - and blocks the real key from entering.

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Aldosterone

• What it is: A hormone made by the adrenal cortex that regulates salt and water balance in the kidneys
• Simple picture: The body's "water manager" - tells the kidney to keep sodium and water, maintain blood pressure.

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Alveoli (singular: Alveolus)

• What they are: Tiny air sacs at the end of the bronchial tree in the lungs where gas exchange happens
• Why in GA: Inhaled anaesthetic agents enter the blood FROM the alveoli; MAC (minimum alveolar concentration) is measured at alveolar level
• Simple picture: Microscopic balloons in the lungs. Oxygen enters the blood here; CO₂ and anaesthetic gases leave here.

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Amnesia

• What it means: Complete loss of memory
• In GA: Patients should have NO memory of surgery (this is a deliberate and desired effect)
• Types:
  • Anterograde amnesia = cannot form NEW memories (during/after drug)
  • Retrograde amnesia = loss of memories BEFORE the drug
• Drugs causing it: Midazolam, benzodiazepines, hyoscine, propofol
• Simple picture: A blank page where the surgical experience should be. The anaesthetic "switches off" the recording function of the brain.

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Ampoule

• What it is: A small sealed glass or plastic container holding a measured dose of a drug
• Simple picture: A tiny glass bottle you snap open to draw up the drug into a syringe.

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Anaphylaxis

• Pronunciation: an-ah-fih-LAK-sis
• What it means: A severe, life-threatening whole-body allergic reaction
• Causes in GA: Suxamethonium, latex, antibiotics, blood products, atracurium (histamine)
• Signs: Hypotension, bronchospasm, urticaria (rash), angioedema, cardiovascular collapse
• Treatment: Adrenaline (epinephrine) 0.5 mg IM → most important first drug
• Simple picture: The immune system going into a full panic attack - it over-reacts to a substance and attacks the body itself.

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Antagonist

• What it means: A drug that BINDS to a receptor but does NOT activate it - it BLOCKS the receptor from being activated by the agonist
• Example: Non-depolarising NMBAs are ANTAGONISTS at nicotinic ACh receptors
• Simple picture: A fake key that fits the lock perfectly but cannot open it - AND stops the real key from getting in.

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Anterograde Amnesia

• See Amnesia above
• Specific meaning: Cannot form memories GOING FORWARD (after the drug is given)
• Example: After midazolam, the patient cannot remember anything that happens next even though they may appear awake and talking
• Simple picture: The camera recording button is switched OFF. Events are happening but not being recorded.

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Apnoea

• Pronunciation: ap-NEE-ah
• What it means: Complete CESSATION (stopping) of breathing
• In GA: Can be caused by induction agents (propofol, thiopentone), opioids, suxamethonium
• Types:
  • Central apnoea = brain not sending breathing signals
  • Obstructive apnoea = airway blocked
• Simple picture: The breathing "on switch" is turned off - either by the brain or by a physical block in the airway.

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Arrhythmia

• Pronunciation: ah-RITH-mee-ah
• What it means: Abnormal heart RHYTHM - heart beats too fast, too slow, or irregularly
• Types in GA context:
  • Bradycardia (too slow < 60 bpm)
  • Tachycardia (too fast > 100 bpm)
  • Ventricular fibrillation (chaotic, life-threatening)
• Caused by: Hyperkalaemia (suxamethonium), oculocardiac reflex, volatile agents, intubation stimulus
• Simple picture: The heart's electrical wiring going haywire - like a clock that sometimes speeds up, slows down, or skips beats.

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Aspiration (Pulmonary Aspiration)

• What it means: Inhaling stomach contents (food, acid, liquid) INTO the lungs
• Why catastrophic: Stomach acid destroys lung tissue → aspiration pneumonitis → ARDS → death
• Prevention: RSI with cricoid pressure, fasting before surgery, antacids, H2 blockers
• Simple picture: Stomach vomit going down the wrong tube (trachea instead of oesophagus) and burning the lungs from the inside.

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Atelectasis

• Pronunciation: at-eh-LEK-tah-sis
• What it means: Collapse of part (or all) of a lung, or failure of alveoli to remain open
• Caused by in GA: Lying flat under anaesthesia reduces functional residual capacity; heavy patients, prolonged surgery
• Simple picture: A deflated section of lung - like a flat tyre in part of the lung.

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Autonomic Nervous System (ANS)

• What it is: The part of the nervous system that controls INVOLUNTARY functions - heart rate, blood pressure, breathing, digestion, secretions
• Two divisions:
  • Sympathetic ("fight or flight") - speeds heart up, dilates pupils, stops digestion
  • Parasympathetic ("rest and digest") - slows heart, increases secretions, promotes digestion
• Why in GA: Many anaesthetic drugs affect the ANS - e.g., atropine blocks parasympathetic, ketamine stimulates sympathetic

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B

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Barotrauma

• Pronunciation: bar-oh-TRAW-mah
• What it means: Injury to lung tissue caused by EXCESSIVE PRESSURE during mechanical ventilation
• Can cause: Pneumothorax (air escaping into chest cavity outside lung)
• Risk factors: Obese patients, laparoscopic surgery (pneumoperitoneum), lung disease
• Simple picture: Blowing up a balloon too hard until it pops - same can happen to the delicate alveoli under high ventilator pressure.

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Beta-Blocker (Beta-adrenergic antagonist)

• What it does: Blocks beta-adrenergic receptors → reduces heart rate and blood pressure
• In GA: Used to blunt the hypertensive/tachycardic response to intubation (e.g., esmolol, metoprolol, labetalol)
• Simple picture: A brake for the heart - slows it down and prevents it from racing during stressful moments like laryngoscopy.

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Blood-Brain Barrier (BBB)

• What it is: A highly selective barrier formed by specialised brain capillaries that controls what enters the brain from the bloodstream
• Why important in GA:
  • Lipophilic drugs cross easily → faster effect (propofol, ketamine, thiopentone)
  • Glycopyrrolate (charged/polar) does NOT cross → no CNS effects
  • Hyoscine and atropine cross → cause CNS effects (sedation, confusion)
• Simple picture: A strict security checkpoint between the blood and the brain. Only certain "passes" (lipid-soluble, uncharged molecules) get through.

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Blood-Gas Partition Coefficient (Blood-Gas Solubility)

• What it means: How much of an inhaled anaesthetic DISSOLVES in blood compared to remaining in the alveolar gas
• Low coefficient = less dissolves in blood = anaesthetic stays in alveoli = FASTER onset AND faster offset
• High coefficient = more dissolves in blood = SLOWER onset and offset (blood acts as a "sponge")

• Simple picture: Imagine dropping dye into water (blood). If it dissolves a LOT, the water stays clear (not much gets to the brain quickly). If it doesn't dissolve much, the dye concentrates in the air - gets to the brain fast.

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Bolus

• What it means: A single, relatively large, rapid dose of a drug given at one time
• Opposite: Infusion (slow continuous delivery over time)
• Simple picture: A single shot vs a slow drip. Bolus = one big shot. Infusion = a drip that runs continuously.

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Bradycardia

• Pronunciation: bray-dee-KAR-dee-ah
• What it means: Abnormally SLOW heart rate (< 60 beats per minute)
• Causes in GA: Vagal stimulation (intubation, surgical manipulation), suxamethonium (especially repeat doses), opioids
• Treatment: Atropine, glycopyrrolate
• Simple picture: The heart running in slow motion - can cause low blood pressure and organ underperfusion if severe.

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Bronchospasm

• What it means: Sudden constriction (narrowing) of the bronchi (airways in the lung) → severe difficulty breathing
• Sounds like: Wheezing, high-pitched breathing
• Caused by: Histamine-releasing NMBAs (atracurium), suxamethonium, pungent volatile agents, intubation in reactive airways
• Treatment: Salbutamol (bronchodilator), ketamine, volatile anaesthetics, adrenaline
• Simple picture: The airways suddenly clamping shut like a fist squeezing a tube - air can't flow in or out properly.

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C

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Cannula (IV Cannula)

• What it is: A thin hollow plastic tube inserted into a vein to allow IV drug/fluid administration
• Also called: IV line, drip, venflon
• Simple picture: A tiny straw placed in the vein - drugs are injected through it.

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Cardiac Output

• What it means: The total amount of blood the heart pumps per minute
• Formula: Heart Rate × Stroke Volume
• In GA: Most induction agents reduce cardiac output (especially thiopentone, propofol)
• Simple picture: How much water a pump moves per minute. If the pump slows down (low heart rate) OR pushes less per beat (low stroke volume) - output falls.

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Cardiopulmonary Bypass (CPB)

• What it is: A machine that temporarily takes over the function of the heart AND lungs during cardiac surgery
• Why in GA: TIVA (propofol + remifentanil) is preferred during CPB because volatile agents are not easily delivered through the bypass circuit
• Simple picture: A heart-lung machine acting as a substitute engine while the surgeon works on the real engine (heart).

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Cerebral Blood Flow (CBF)

• What it means: Blood flow to the brain
• Normal: ~50 ml/100g/min
• In GA: Thiopentone and propofol reduce CBF (and ICP). Ketamine INCREASES CBF (and ICP).
• Simple picture: The water supply to the brain. Some anaesthetics reduce the flow (useful in brain swelling), ketamine increases it (dangerous in brain injury).

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Cerebral Metabolic Rate (CMR)

• What it means: How much oxygen and glucose the brain consumes per minute
• In GA: Thiopentone dramatically reduces CMR → protective in brain ischaemia
• Simple picture: How hard the brain's engine is running. Thiopentone turns the engine down to idle speed, reducing oxygen needs - protecting the brain.

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Cholinergic

• What it means: Related to acetylcholine (ACh) - either releasing it, or responding to it
• Cholinergic effects (when ACh increases):
  • Bradycardia
  • Increased secretions (saliva, tears, gastric acid)
  • Bronchospasm
  • Miosis (pupil constriction)
  • Increased bowel movements
• Why in GA: Neostigmine causes cholinergic side effects → need glycopyrrolate to counter them
• Simple picture: Imagine turning the "rest and digest" system to maximum - heart slows, everything secretes, bowels move.

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Compliance (Lung Compliance)

• What it means: How easily the lungs EXPAND when filled with air
• High compliance = lungs stretch easily (normal/emphysema)
• Low compliance = stiff lungs, need more pressure to expand (fibrosis, ARDS, obesity)
• In GA: In pressure-controlled ventilation, the tidal volume VARIES depending on compliance
• Simple picture: Lung compliance = how stretchy the lung balloon is. A new balloon is hard to blow up (low compliance). A used, stretched balloon is easy (high compliance).

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Context-Sensitive Half-Life

• What it means: How the time it takes for a drug's plasma concentration to fall by 50% CHANGES depending on how LONG it has been infused
• Simple example:
  • Most drugs: longer infusion → drug accumulates in tissues → half-life INCREASES
  • Remifentanil: half-life stays at 3-5 min REGARDLESS of infusion duration → context-INSENSITIVE
• Why important: Remifentanil's predictable disappearance makes it ideal for TIVA
• Simple picture: Imagine a bathtub. Most drugs: the longer you run water (infuse), the longer it takes to drain when you pull the plug. Remifentanil's drain is so efficient it empties in the same time whether you ran it 5 minutes or 5 hours.

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Cortisol

• What it is: The primary "stress hormone" made by the adrenal cortex
• Functions: Helps body respond to stress, maintains blood pressure, anti-inflammatory, regulates blood sugar
• In GA: Etomidate blocks cortisol production → concern especially in critically ill patients
• Simple picture: The body's "emergency kit" hormone. When you're stressed (surgery), you need cortisol to cope. Etomidate empties the kit.

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Cricoid Cartilage

• What it is: The ONLY complete ring-shaped cartilage in the larynx/trachea (all others are C-shaped)
• Location: Just below the thyroid cartilage (Adam's apple), above the trachea
• In GA: Cricoid pressure (Sellick's manoeuvre) compresses this against the spine to occlude the oesophagus during RSI
• Simple picture: The one complete ring in the throat's stack of rings. Because it's complete, pressing it squeezes the oesophagus behind it shut.

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Cycloplegia

• Pronunciation: sy-kloh-PLEE-jee-ah
• What it means: Paralysis of the ciliary muscle of the eye → inability to focus (accommodation)
• Caused by: Anticholinergic drugs (atropine, hyoscine)
• Simple picture: The focusing muscle of the eye is paralysed - everything close up appears blurred.

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Cyclodextrin

• What it is: A ring-shaped sugar molecule that can form a "cage" or "barrel" around other molecules
• In GA: Sugammadex is a modified gamma-cyclodextrin - its barrel-shaped structure physically encloses and traps rocuronium
• Simple picture: A hollow ring-shaped donut made of sugar. Rocuronium fits inside the donut hole perfectly - once trapped inside, it can't act anymore.

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D

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Depolarisation

• What it means: A change in the electrical charge across a cell membrane from negative to positive (inside becomes positive relative to outside)
• In muscles: Depolarisation triggers muscle contraction
• In NMBAs: Suxamethonium causes PERSISTENT depolarisation (keeps the membrane positive) → muscle cannot repolarise → cannot contract again → relaxation
• Simple picture: Normal: switch flips on (depolarise) → muscle fires → switch returns to off (repolarise) → muscle relaxes. Suxamethonium: switch gets JAMMED in the ON position → muscle can't fire again = relaxation.

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Desaturation (Oxygen Desaturation)

• What it means: A fall in blood oxygen saturation (SpO₂) below normal levels (normal > 95%)
• In GA: Can occur at induction (apnoea), during maintenance (airway problems), or at extubation
• Prevention: Pre-oxygenation before induction; careful airway management
• Simple picture: The oxygen level in the blood dropping - like a phone battery running down.

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Dissociation / Dissociative State

• What it means: A state where the brain's processing of sensory information (pain, awareness) is SEPARATED from consciousness - the person appears awake but is disconnected from reality
• Caused by: Ketamine
• Features: Eyes may be open, laryngeal reflexes preserved, breathing continues - but patient is unaware and pain-free
• Simple picture: Imagine your consciousness is in one room and your body is in another room. You can't feel what's happening to your body. That's dissociation.

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Diuretic

• What it means: A drug that increases urine production
• Why in GA context: Mannitol (an osmotic diuretic) is used in neurosurgery to reduce brain swelling (ICP)
• Simple picture: A drug that makes you urinate more - helps remove excess fluid from the body (or brain tissue).

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E

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Elimination Half-Life

• What it means: The time it takes for the concentration of a drug in the blood to fall by HALF (50%)
• Short half-life = drug clears quickly (e.g., remifentanil = 3-5 min)
• Long half-life = drug stays in system longer (e.g., diazepam = 20-100 hours)
• Simple picture: If you have 100 units of a drug and the half-life is 1 hour → after 1 hour = 50 units → after 2 hours = 25 units → etc.

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Emesis

• What it means: Vomiting
• PONV = Post-Operative Nausea and Vomiting - very common after GA
• Simple picture: Throwing up. PONV = throwing up after surgery. Propofol reduces this, N₂O worsens it.

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Emulsion

• What it is: A mixture where tiny droplets of one liquid are suspended in another (like oil in water)
• In GA: Propofol is a white oil-in-water emulsion (lipid emulsion - soybean oil + egg lecithin)
• Why it matters: Supports bacterial growth if not used promptly; egg allergy → caution with propofol
• Simple picture: Salad dressing (oil droplets in vinegar) - propofol looks exactly like milk because it's an oil-in-water emulsion.

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Endotracheal Tube (ETT)

• What it is: A flexible plastic tube inserted through the mouth → vocal cords → trachea (windpipe) to maintain a secure airway during GA
• Components: Tube body, cuff (inflatable balloon that seals the trachea), pilot balloon, connector
• Simple picture: A straw placed in the windpipe. The balloon (cuff) seals the straw in place, preventing leaks and aspiration.

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Enzyme

• What it is: A biological molecule (protein) that SPEEDS UP chemical reactions in the body without being consumed itself
• Examples in GA:
  • Acetylcholinesterase (breaks down ACh)
  • Plasma pseudocholinesterase (breaks down suxamethonium)
  • 11-β hydroxylase (makes cortisol - blocked by etomidate)
• Simple picture: A biological factory machine. It processes materials but doesn't get used up in the process. Block the machine (inhibit the enzyme) = the process stops.

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Eutectic Mixture

• What it means: A mixture of two substances that has a LOWER melting point than either substance alone
• In GA: EMLA cream = eutectic mixture of lignocaine + prilocaine (both are solid at room temperature, but the mixture is liquid/cream at room temperature)
• Simple picture: Like mixing two solid chocolates that somehow produce a liquid together - the eutectic mixture becomes a cream because the melting point drops when combined.

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Extubation

• What it means: REMOVAL of the endotracheal tube at the end of surgery
• Requirements: Patient awake, breathing adequately, muscle relaxation reversed, airway reflexes present
• Simple picture: Taking out the breathing tube when the patient is waking up and can breathe and protect their own airway.

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F

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Fasciculation

• Pronunciation: fah-sik-yoo-LAY-shun
• What it means: Brief, involuntary, visible muscle twitching affecting individual muscle bundles
• In GA: Occur after suxamethonium injection (depolarisation of muscle fibres before relaxation)
• Why it matters: Causes post-operative muscle pain (myalgia); raises intraocular pressure, intragastric pressure
• Simple picture: Random, flickering muscle twitches visible under the skin - like a muscle having a brief hiccup all over the body simultaneously after suxamethonium.

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Fluorine / Fluorinated

• What it is: Fluorine is a chemical element (F) added to the carbon backbone of volatile anaesthetics
• Why: Fluorination makes volatile agents stable, non-flammable, and gives them their specific properties
• Examples: Sevoflurane, isoflurane, desflurane - all contain fluorine
• Simple picture: Fluorine is the "special ingredient" added to volatile agents to make them safe, stable, and effective anaesthetics.

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Functional Residual Capacity (FRC)

• What it means: The volume of air remaining in the lungs AFTER a normal (passive) expiration
• Why in GA: FRC decreases under GA (especially supine position) → earlier desaturation; pre-oxygenation fills this reservoir with oxygen
• Simple picture: The air left in your lungs after breathing out normally. This is the oxygen reserve. GA reduces this reserve - which is why pre-oxygenation is so important.

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G

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Gangrene

• What it means: Death of body tissue, usually due to loss of blood supply or severe infection
• In GA context: If thiopentone (highly alkaline, pH 10.8) is accidentally injected into an ARTERY → intense vasospasm → ischaemia → gangrene of the affected limb
• Simple picture: Tissue dying because its blood supply is cut off. Thiopentone in an artery is like pouring acid into a water pipe - it spasms shut and the tissue downstream dies.

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Gastric Emptying

• What it means: The speed at which the stomach empties its contents into the duodenum
• In GA: Delayed gastric emptying (opioids, pregnancy, diabetes, pain, bowel obstruction) = more food/fluid in stomach = higher aspiration risk
• Standard fasting before GA: 6 hours for solid food, 2 hours for clear fluids
• Simple picture: How quickly the stomach passes food downward. Slow emptying = full stomach = dangerous during induction.

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GABA (Gamma-Aminobutyric Acid)

• What it is: The most important INHIBITORY neurotransmitter in the brain
• How it works: Opens chloride channels → makes nerve cells MORE negative inside → harder to fire
• In GA: Propofol, thiopentone, benzodiazepines, volatile agents ALL enhance GABA → suppress brain activity → unconsciousness
• Simple picture: GABA is the brain's "calm down" chemical. Anaesthetics turbocharge GABA → brain goes to sleep.

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Glottis

• What it is: The opening between the vocal cords (the entry point to the trachea/lungs)
• In GA: The ETT passes THROUGH the glottis. Supraglottic airways (LMA) sit ABOVE it.
• Simple picture: The doorway into the windpipe. The vocal cords are the door. The ETT goes through the door; the LMA sits in front of the door.

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H

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Haemodynamics

• What it means: Everything related to blood flow and pressure in the cardiovascular system (heart rate, blood pressure, cardiac output, vascular resistance)
• Haemodynamically stable = blood pressure and heart rate are normal and steady
• Haemodynamically unstable = blood pressure crashing, heart rate abnormal
• Simple picture: The "traffic report" of the cardiovascular system - is blood flowing well and at the right pressure?

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Halogenated

• What it means: A chemical compound containing halogen atoms (fluorine, chlorine, bromine, iodine)
• In GA: Volatile anaesthetics are halogenated ethers/hydrocarbons - the halogen (usually fluorine) gives them their anaesthetic and stability properties
• Simple picture: Volatile agents are "flavoured" with fluorine atoms, which is what makes them work as anaesthetics.

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Histamine

• What it is: A chemical released from mast cells during allergic reactions
• Effects: Vasodilation (BP drops), bronchoconstriction (airways narrow), increased secretions, itching, urticaria (rash)
• In GA: Atracurium and suxamethonium can cause histamine release even without true allergy
• Simple picture: The body's "alarm chemical" released when it thinks something foreign/dangerous is present. Too much histamine = allergic/anaphylactic reaction.

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Hofmann Degradation / Elimination

• What it means: Spontaneous chemical breakdown of a molecule at normal physiological temperature (37°C) and pH (7.4) - WITHOUT requiring any organ (liver or kidney)
• Drug using this: Atracurium, cisatracurium
• Products: Laudanosine + acrylate (broken down in the body)
• Simple picture: The drug self-destructs in the bloodstream - like a timed explosive that goes off by itself. No organ needs to do any work.

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Hypercapnia

• Pronunciation: hy-per-KAP-nee-ah
• What it means: Abnormally HIGH CO₂ in the blood (> 45 mmHg)
• Causes in GA: Inadequate ventilation, airway obstruction, rebreathing
• Effects: Respiratory acidosis, increased intracranial pressure, arrhythmias
• Simple picture: The blood getting too "gassy" with waste CO₂ because it's not being breathed out fast enough.

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Hyperkalaemia

• What it means: Abnormally HIGH potassium level in the blood (> 5.5 mEq/L)
• In GA: Suxamethonium causes K⁺ release from depolarising muscles → dangerous in burns, crush injuries, spinal cord injuries, prolonged immobility
• Danger: Cardiac arrhythmias → ventricular fibrillation → cardiac arrest
• Simple picture: Muscles all fire (fasciculations) and release potassium into the blood → too much potassium → heart's electrical system goes haywire.

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Hypotension

• What it means: Abnormally LOW blood pressure (systolic < 90 mmHg, or > 20% drop from baseline)
• Common causes in GA: Propofol (vasodilation), thiopentone, opioids, hypovolaemia, deep anaesthesia
• Risks: Organ underperfusion (brain, kidneys, heart)
• Treatment: IV fluids, vasopressors (noradrenaline, phenylephrine, ephedrine), reduce anaesthetic depth
• Simple picture: Blood pressure crashing - like insufficient water pressure in a pipe system, organs don't get enough blood.

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Hypovolaemia

• Pronunciation: hy-poh-voh-LEE-mee-ah
• What it means: Abnormally LOW circulating blood volume (dehydration, bleeding)
• In GA: Makes patients more sensitive to anaesthetic-induced hypotension
• Simple picture: A car engine running on low oil - any additional demand (like an anaesthetic drug causing vasodilation) makes things worse.

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Hypoxia

• Pronunciation: hy-POX-ee-ah
• What it means: Insufficient oxygen SUPPLY to tissues
• Hypoxaemia = low oxygen in the BLOOD (SpO₂ < 95%)
• In GA: Can occur from airway obstruction, apnoea, equipment failure, bronchospasm
• Simple picture: The body's tissues starving for oxygen - cells begin to die after a few minutes without adequate oxygen (brain cells within 4-6 minutes).

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I

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Infusion

• What it means: Continuous, slow delivery of a drug or fluid directly into the vein over time
• Used for: TIVA (propofol infusion), remifentanil infusion, neuromuscular blocker infusion
• Simple picture: A drip running steadily - like a slow, controlled tap rather than one sudden pour.

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Intraocular Pressure (IOP)

• What it means: The fluid pressure INSIDE the eyeball
• Normal: 10-21 mmHg
• In GA: Suxamethonium RAISES IOP (briefly) due to fasciculations of extraocular muscles; ketamine raises IOP
• Clinical importance: In open globe injury (ruptured eyeball) → raised IOP → vitreous may be expelled → permanent vision loss
• Simple picture: The pressure inside a water balloon (the eye). Squeezing the balloon (fasciculations/raised IOP) can push the contents out if there's a hole.

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Intragastric Pressure

• What it means: The pressure INSIDE the stomach
• In GA: Suxamethonium fasciculations raise intragastric pressure → can overcome the lower oesophageal sphincter → regurgitation → aspiration risk
• Simple picture: Squeezing the stomach from outside (fasciculations) increases the pressure and can force stomach contents upward into the oesophagus.

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Intubation

• What it means: Placement of a tube into a hollow organ
• In GA: Endotracheal intubation = placing an ETT into the trachea
• Simple picture: Threading a straw into the windpipe to secure the airway.

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Ischaemia

• Pronunciation: is-KEE-mee-ah
• What it means: Insufficient blood supply to a tissue/organ → oxygen deprivation → tissue damage
• In GA context: Hypotension → cardiac/cerebral/renal ischaemia; arterial thiopentone injection → limb ischaemia
• Simple picture: Starving a tissue of its blood supply - like cutting off water to a plant.

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L

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Laryngoscopy

• What it means: Direct visual examination of the larynx (voice box/glottis) using a laryngoscope
• Used for: Guiding ETT placement; assessing difficult airway
• Types: Direct (Macintosh blade), Video (McGrath, C-MAC)
• Simple picture: Shining a light and looking into the throat with a special metal blade to see the vocal cords.

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Laryngospasm

• What it means: Sudden, involuntary, sustained CLOSURE of the vocal cords → complete airway obstruction
• Causes in GA: Airway irritation (secretions, blood, pungent volatile agents like desflurane), light anaesthesia during airway instrumentation
• Treatment: Positive pressure ventilation, propofol (small dose), suxamethonium (if severe, life-threatening)
• Simple picture: The vocal cords slamming shut and refusing to open - like a door suddenly jamming. Air cannot enter the lungs.

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Laudanosine

• What it is: A metabolite (breakdown product) of atracurium after Hofmann degradation
• Concern: In very high doses, theoretically causes CNS stimulation (seizures in animal models)
• Clinical significance: Not clinically significant at normal anaesthetic doses
• Simple picture: The "leftover" product after atracurium self-destructs in the body.

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Lipophilic

• Pronunciation: lip-oh-FIL-ik
• What it means: Attracted to fats/lipids (fat-LOVING)
• In GA: Lipophilic drugs cross the blood-brain barrier easily → faster onset of CNS effects
• Examples: Propofol, thiopentone, fentanyl - all highly lipophilic
• Simple picture: Fat-loving molecules slide through the fatty brain barrier easily, like oil through an oily surface.

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M

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Malignant Hyperthermia (MH)

• What it means: A life-threatening, pharmacogenetic (inherited drug reaction) disorder causing uncontrolled skeletal muscle metabolism
• Triggers: Suxamethonium, all volatile anaesthetic agents (halothane, sevoflurane, isoflurane, desflurane)
• Mechanism: Mutation in ryanodine receptor (RYR1) → uncontrolled calcium release → muscle hypermetabolism
• Signs: Rising end-tidal CO₂, hyperthermia (fever > 40°C, temperature rises rapidly), muscle rigidity, tachycardia, metabolic acidosis
• Treatment: STOP trigger → Dantrolene IV (the ONLY specific drug) → cooling + supportive care
• Simple picture: The muscle's calcium regulation system breaks down - muscles go into full overdrive, burning fuel and generating extreme heat, like an engine with no cooling system.

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Metabolite

• What it means: A chemical substance produced when the body breaks down (metabolises) a drug
• Examples in GA: Laudanosine (from atracurium), norpethidine (from pethidine - causes seizures in high doses)
• Simple picture: The "leftover pieces" after the body's chemical factory processes a drug.

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Miosis

• Pronunciation: my-OH-sis
• What it means: Constriction (narrowing) of the pupil
• Caused by: Opioids (all opioids cause miosis - "pinpoint pupils"), cholinergic drugs
• Simple picture: The pupil shrinking to a tiny dot. Classic sign of opioid use/overdose.

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Mydriasis

• Pronunciation: my-DRY-ah-sis
• What it means: Dilation (widening) of the pupil
• Caused by: Anticholinergic drugs (atropine, hyoscine), sympathomimetic drugs (ketamine)
• Simple picture: The pupil opening wide like a camera aperture being opened. Atropine was used historically for this (belladonna = "beautiful lady" because dilated pupils were considered attractive).

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Myalgia

• What it means: Muscle pain/aching
• In GA: A common side effect of suxamethonium due to fasciculations (muscle fibres forcefully contract briefly → soreness next day)
• Simple picture: Like the muscle soreness after an intense workout - except you get it without any exercise, just from suxamethonium-induced fasciculations.

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N

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Neuromuscular Junction (NMJ)

• What it is: The specialised synapse (junction/connection point) between a motor neurone and a skeletal muscle fibre
• How it works:
  1. Nerve signal arrives at nerve terminal
  2. ACh is released into the synaptic cleft (gap)
  3. ACh binds to nicotinic receptors on muscle
  4. Muscle depolarises and contracts
  5. Acetylcholinesterase destroys ACh
  6. Muscle repolarises and relaxes
• Simple picture: A telephone line connection between a nerve and a muscle. The nerve calls, the muscle answers and moves. NMBAs cut the line.

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Nicotinic Receptor

• What it is: A subtype of acetylcholine receptor found at the neuromuscular junction (and in autonomic ganglia)
• Activated by: Acetylcholine, nicotine (hence the name), suxamethonium
• Blocked by: Non-depolarising NMBAs
• Compare with: Muscarinic receptors (found in heart, glands, smooth muscle - blocked by atropine)
• Simple picture: The specific "lock" at the neuromuscular junction that the ACh "key" fits into. Suxamethonium also fits this lock and turns it. Non-depolarising NMBAs jam the lock.

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Nitrous Oxide (N₂O)

• See main notes. Additional clarification:
• Why MAC > 100%?: N₂O's MAC is 104% at 1 atmosphere (normal atmospheric pressure). This means you'd need MORE than 100% of inspired gas to be N₂O to anaesthetise 50% of patients - physically impossible at normal pressure. So N₂O CANNOT produce full anaesthesia alone at sea level.
• Simple picture: N₂O is a weak anaesthetic - it reduces the amount of other agents needed but can't do the job alone.

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NMDA Receptor

• Full name: N-Methyl-D-Aspartate receptor
• What it is: An excitatory glutamate receptor in the brain and spinal cord - involved in pain transmission, memory formation, and consciousness
• Blocked by: Ketamine (mechanism of dissociative anaesthesia)
• Simple picture: An "excitement switch" in the brain. Ketamine locks this switch in the OFF position → no pain signals processed → no memories formed → dissociation.

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O

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Oesophagus

• What it is: The muscular tube connecting the throat (pharynx) to the stomach - the FOOD pipe
• In GA: Must be distinguished from trachea during intubation (oesophageal intubation = no ventilation = hypoxia). Cricoid pressure compresses it during RSI.
• Simple picture: The food pipe - runs behind (posterior to) the trachea. If the breathing tube goes into the oesophagus instead of the trachea, the patient can't breathe and stomach gas gets pumped in.

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Opioid Receptor

• Types: Mu (μ), Kappa (κ), Delta (δ)
• Mu receptor = most important for anaesthesia/analgesia: analgesia, sedation, respiratory depression, euphoria, constipation, miosis
• In GA: All opioids (morphine, fentanyl, remifentanil) mainly act on mu receptors
• Simple picture: The "painkiller docking station" in the brain and spinal cord. Opioids dock here to block pain signals.

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P

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Pharmacodynamics

• What it means: What the DRUG does to the BODY (mechanism of action, effects)
• Simple picture: "The drug's story" - how it works inside the body.

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Pharmacokinetics

• What it means: What the BODY does to the DRUG (absorption, distribution, metabolism, excretion - ADME)
• Simple picture: "The body's story" - how the body handles and processes the drug.

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Pneumothorax

• Pronunciation: new-moh-THOR-ax
• What it means: Air trapped in the PLEURAL CAVITY (the space between the lung and the chest wall) → lung collapses
• In GA: Risk of barotrauma (over-pressure ventilation); N₂O contraindicated (it expands the pneumothorax)
• Simple picture: Air escaping from the lung into the chest space - like a flat tyre inside the chest. The lung is compressed and cannot expand.

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PONV (Post-Operative Nausea and Vomiting)

• What it means: Nausea and/or vomiting occurring after surgery/anaesthesia
• Causes: Opioids, N₂O, volatile agents, motion, pain
• Prevention: Propofol (TIVA), ondansetron, dexamethasone, avoiding N₂O and long-acting opioids
• Simple picture: The sick feeling and/or throwing up that commonly happens after surgery - a major cause of patient dissatisfaction and delayed discharge.

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Pulmonary Aspiration

• See Aspiration above

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Pseudocholinesterase (Plasma Cholinesterase, Butyrylcholinesterase)

• What it is: An enzyme found in plasma (blood) that breaks down suxamethonium (and mivacurium, ester local anaesthetics)
• In GA: If deficient or abnormal (genetic condition) → suxamethonium is NOT broken down → prolonged paralysis (hours of apnoea)
• Simple picture: The scissor enzyme in the blood that cuts up suxamethonium. If the scissors are broken or missing → suxamethonium stays active for hours instead of minutes.

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R

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Regurgitation

• What it means: Passive backflow of stomach contents UP into the oesophagus/pharynx WITHOUT forceful vomiting
• Why dangerous in GA: Occurs when lower oesophageal sphincter tone is lost (as in induction) + patient is unconscious → cannot cough it out → aspirates it
• In GA: The concern with RSI - regurgitation (passive, silent) is the real danger, not active vomiting
• Simple picture: Stomach contents silently sliding up the food pipe like water reversing in a pipe - no heaving or warning. Especially dangerous because the patient is unconscious.

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Repolarisation

• What it means: The return of a cell membrane's electrical charge back to its resting (negative inside) state AFTER depolarisation
• Normal muscle function: Depolarise (fire) → repolarise (reset) → ready to fire again
• Suxamethonium problem: Keeps membrane depolarised (positive) → can't repolarise → can't contract again = relaxation
• Simple picture: Resetting a fired gun. Normal: fire → reset → ready. Suxamethonium: fires the gun and keeps the trigger held down → gun cannot reset.

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Respiratory Depression

• What it means: Reduced rate and/or depth of breathing caused by a drug
• Caused by: Opioids, benzodiazepines, induction agents, volatile agents
• Can lead to: Apnoea, hypercapnia, hypoxia
• Simple picture: The breathing "drive" being turned down - the brain sends fewer signals to breathe, or weaker signals.

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Reversal Agent

• What it means: A drug given to UNDO/REVERSE the effects of another drug
• In GA: Neostigmine reverses non-depolarising NMBAs; sugammadex reverses rocuronium/vecuronium; flumazenil reverses benzodiazepines; naloxone reverses opioids
• Simple picture: An "antidote" for the anaesthetic drug - cancels its effects.

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S

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Sedation

• What it means: A drug-induced state of reduced anxiety, calmness, and drowsiness - without full unconsciousness
• Levels: Minimal → Moderate → Deep → GA (full unconsciousness)
• Used in GA as: Premedication, procedural sedation, ICU sedation
• Simple picture: Dialling down awareness and anxiety without completely switching the lights off.

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Serotonin Syndrome

• What it means: A potentially life-threatening drug reaction caused by excess serotonin activity in the nervous system
• In GA context: Pethidine + MAO inhibitors → serotonin syndrome (agitation, hyperthermia, muscle rigidity, seizures, death)
• Simple picture: Serotonin (the "feel-good" neurotransmitter) flooding the system uncontrollably - like a gas pedal stuck to the floor.

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Sphincter

• What it means: A circular muscle that can open and close to control passage through an opening
• In GA context: Lower oesophageal sphincter (LOS) separates the oesophagus from the stomach. Regurgitation occurs when this sphincter tone is lost under anaesthesia.
• Simple picture: A valve. The lower oesophageal sphincter is the valve between stomach and food pipe - it normally stays closed to prevent acid reflux.

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Stroke Volume

• What it means: The amount of blood pumped out of the left ventricle with EACH heartbeat
• Formula: Cardiac Output = Heart Rate × Stroke Volume
• In GA: Reduced by myocardial depression (thiopentone, propofol) → reduced cardiac output
• Simple picture: How much blood the heart squirts out with each squeeze.

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Sympathomimetic

• What it means: A drug that MIMICS the effects of the sympathetic nervous system (adrenaline-like effects)
• Effects: Increases heart rate, raises blood pressure, dilates pupils, dilates bronchi
• In GA: Ketamine is a sympathomimetic → raises BP (unlike other induction agents)
• Simple picture: Pressing the body's "accelerator pedal" - speeds the heart up and raises blood pressure.

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Synapse

• What it is: The microscopic gap between two nerve cells (or between a nerve and a muscle) across which chemical messages (neurotransmitters) are passed
• Simple picture: The gap between two people reaching to hand over a message. The message (neurotransmitter) must cross the gap to be received.

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T

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Tachycardia

• Pronunciation: tak-ee-KAR-dee-ah
• What it means: Abnormally FAST heart rate (> 100 beats per minute)
• Causes in GA: Atropine (desired), ketamine (sympathomimetic), pain/light anaesthesia, hypovolaemia, malignant hyperthermia
• Simple picture: The heart racing - like an engine running at too high a speed.

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Tachyphylaxis

• Pronunciation: tak-ee-fih-LAK-sis
• What it means: Rapidly decreasing response to a drug after repeated doses (acute drug tolerance)
• In GA context: Remifentanil tachyphylaxis can occur with prolonged infusions
• Simple picture: The first time you press a button the response is strong; each subsequent press gets weaker - the system gets used to the stimulus and responds less.

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Titration

• What it means: Carefully adjusting a drug dose UP or DOWN in small increments to achieve the desired effect while minimising side effects
• In GA: Titrating volatile agent concentration, titrating propofol infusion rate
• Simple picture: Fine-tuning the volume dial on a stereo - small adjustments rather than sudden big changes.

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Trachea

• What it is: The windpipe - the cartilaginous and fibromuscular tube that carries air from the larynx to the main bronchi
• Length: ~10-12 cm in adults
• In GA: ETT is placed into the trachea; correct placement confirmed by capnography (CO₂ waveform)
• Simple picture: The main air highway - the central pipe carrying air to both lungs.

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Train-of-Four (TOF)

• What it is: A neuromuscular monitoring technique using 4 electrical stimuli delivered to a peripheral nerve at 0.5-second intervals
• What it measures: The depth of neuromuscular block
• Reading TOF:
  • 4/4 twitches of equal strength = no block
  • 4/4 with fade = partial block
  • 3/4, 2/4, 1/4 = increasing depth of block
  • 0/4 = complete block (deep/cannot be reversed by neostigmine)
• TOF ratio > 0.9 = adequate recovery = safe to extubate
• Simple picture: Like testing how many fingers you can feel out of 4 - counts how many of 4 muscle responses get through the block.

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Trimeprazine (Alimemazine)

• Type: Phenothiazine antihistamine
• Use: Oral premedication in children
• Simple picture: A mild antihistamine sedative given as syrup to calm and sedate children before GA induction.

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U

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Urticaria

• Pronunciation: ur-tih-KAR-ee-ah
• What it means: Hives - itchy, raised, red welts on the skin (a sign of allergic reaction/histamine release)
• In GA: Can appear after suxamethonium or atracurium (histamine-releasing NMBAs), or during anaphylaxis
• Simple picture: The classic red itchy bumps of an allergic skin reaction.

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V

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Vagus Nerve (Cranial Nerve X)

• What it is: The 10th cranial nerve - the main parasympathetic nerve of the body
• Effects on heart: Slows heart rate (vagal tone → bradycardia)
• Vagal stimulation in GA: Laryngoscopy, intubation, surgical manipulation → bradycardia
• Blocked by: Atropine, hyoscine, glycopyrrolate (vagolytic drugs)
• Simple picture: The "brake" of the heart - when stimulated, it slows the heart down. Anticholinergic drugs release the brake.

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Vasoconstriction

• What it means: Narrowing of blood vessels → increased resistance → increased blood pressure
• In GA: Noradrenaline, phenylephrine used to treat anaesthesia-induced hypotension
• Simple picture: Squeezing a garden hose - the water pressure increases. Vasoconstriction squeezes the blood vessels → pressure goes up.

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Vasodilation

• What it means: Widening of blood vessels → decreased resistance → decreased blood pressure
• In GA: Propofol, thiopentone, volatile agents all cause vasodilation → hypotension
• Simple picture: Relaxing a squeezed garden hose - the water pressure drops. Blood vessels widen → pressure falls.

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Vaporiser

• What it is: The component of the anaesthetic machine that converts liquid volatile anaesthetic into vapour at a precise, controlled concentration
• Different for each agent: Desflurane requires a HEATED, pressurised vaporiser because its boiling point (23.5°C) is close to room temperature
• Simple picture: A precision perfume diffuser on the anaesthetic machine - converts the liquid anaesthetic into a measured concentration of breathable vapour.

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Vasopressor

• What it means: A drug that constricts blood vessels and RAISES blood pressure
• Examples: Noradrenaline (norepinephrine), phenylephrine, ephedrine, metaraminol
• In GA: Used to treat hypotension caused by anaesthetic agents
• Simple picture: Blood pressure medicine given by drip during surgery to keep the BP from falling too low.

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Ventilation

• What it means: The movement of air in and out of the lungs
• Types in GA:
  • Spontaneous ventilation: patient breathes on their own
  • Controlled/mechanical ventilation: machine breathes for the patient
• Simple picture: The act of breathing - either your own or done by a machine.

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Volatile Agent / Volatile Anaesthetic

• What it means: An anaesthetic that is liquid at room temperature but VAPORISES easily and is administered as an inhaled vapour
• Simple picture: Like perfume - liquid in a bottle, vapour when you spray it. The anaesthetic machine sprays the volatile agent into the breathing circuit.

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W

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Wakefulness / Awareness Under Anaesthesia

• What it means: The terrifying and rare situation where a patient is CONSCIOUS and potentially can feel/hear during surgery but cannot move (due to NMBAs) or communicate
• Prevention: BIS monitoring, adequate depth of anaesthesia, avoid sole reliance on NMBAs
• Incidence: ~1 in 20,000 GA cases
• Simple picture: Being "locked in" - awake inside but unable to signal. Prevention with depth monitors like BIS is why monitoring matters.

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QUICK LOOK-UP TABLE - Most Commonly Confused Terms

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How to use during reading: Any time you hit a word that slows you down, search this guide. The goal is zero reading interruptions - every block removed, every word made simple and clear.