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■ PREOPERATIVE ASSESSMENT Yield Question / Topic ★ ×N ■ HIGH YIELD – Must Know HIGH YIELD ASA Classification – ASA physical status I–VI; clinical examples; implications for anaesthesia ★★★★★ ×8 HIGH YIELD Pre-operative Airway Assessment – Mallampati score (I–IV); other predictors (thyromental distance, mouth opening, neck mobility); predicted difficult airway management algorithm ★★★★★ ×8 HIGH YIELD Fasting Guidelines – current recommendations (2h for clear fluids, 6h solids); RSI indication ★★★★★ ×7 ■ MIDDLE YIELD – Important MID YIELD Pre-anaesthetic Checkup – checklist; informed consent; pre-medication (Midazolam, Glycopyrrolate, antacid) ★★★■■ ×6 MID YIELD Cardiovascular/Respiratory Complications of GA – enumerate; management intraoperatively ★★★■■ ×4 ■ GENERAL ANAESTHESIA Yield Question / Topic ★ ×N ■ HIGH YIELD – Must Know HIGH YIELD IV Induction Agents – Propofol (advantages/disadvantages) vs Thiopentone vs Ketamine (haemodynamic effects; TIVA use) ★★★★★ ×9 HIGH YIELD Volatile Anaesthetic Agents – Isoflurane/Sevoflurane/Desflurane; MAC concept; cardiovascular/respiratory effects ★★★★★ ×7 HIGH YIELD Muscle Relaxants – Suxamethonium (depolarising; contraindications; phase I/II block) vs Non-depolarising (Vecuronium/Atracurium/Rocuronium) ★★★★★ ×7 HIGH YIELD Neostigmine Reversal – mechanism (AChE inhibitor); why add Atropine/Glycopyrrolate (block muscarinic side effects) ★★★★★ ×7 ■ MIDDLE YIELD – Important MID YIELD Nitrous Oxide – advantages (analgesic, rapid onset) and disadvantages (PONV, expansion of gas-filled cavities, B12 inactivation) ★★★■■ ×6 MID YIELD Premedication Drugs – purpose; Midazolam (anxiolysis), Glycopyrrolate (antisialagogue), H2 blocker, Metoclopramide ★★★■■ ×5 MID YIELD Opioids – Fentanyl, Morphine, Tramadol; properties; side effects; reversal (Naloxone) ★★★■■ ×4 ■ REGIONAL ANAESTHESIA Yield Question / Topic ★ ×N ■ HIGH YIELD – Must Know HIGH YIELD Spinal vs Epidural – differences (dural puncture, drug volume, onset, level of block, catheter); complications; contraindications ★★★★★ ×9 HIGH YIELD Complications of Spinal Anaesthesia – hypotension (Ephedrine/phenylephrine), PDPH (blood patch), high spinal, urinary retention ★★★★★ ×7 ■ MIDDLE YIELD – Important TU/IOM Final MBBS – System-wise High-Yield Past Question Analysis (2069–2082) Page 17 MID YIELD MID YIELD MID YIELD Local Anaesthetics – Lidocaine vs Bupivacaine (potency, safe dose, duration, toxicity); mechanism (Na+ channel block) ★★★■■ ×6 Brachial Plexus Block – anatomy; approaches (interscalene/supraclavicular/infraclavicular/axillary); uses ★★★■■ ×5 Epidural Analgesia – technique; advantages (post-op pain, labour); complications; contraindications ★★★■■ ×5 ■ EMERGENCY / RESUSCITATION Yield Question / Topic ★ ×N ■ HIGH YIELD – Must Know HIGH YIELD Adult ACLS – shockable (VF/pulseless VT: defibrillation + CPR + Adrenaline + Amiodarone) vs non-shockable (PEA/asystole: CPR + Adrenaline); 4H/4T reversible causes ★★★★★ ×9 HIGH YIELD CPR – high-quality chest compression (rate 100–120/min, depth 5–6 cm, full recoil, minimise interruptions); Epinephrine dose/timing; other drugs (Amiodarone, Atropine, MgSO■) ★★★★★ ×8 HIGH YIELD RSI – definition; steps; indications; suxamethonium (fasciculations; K■ rise; modified RSI with Rocuronium) ★★★★★ ×7 ■ FLUIDS & NUTRITION Yield Question / Topic ★ ×N ■ MIDDLE YIELD – Important MID YIELD MID YIELD MID YIELD MID YIELD IV Fluids – crystalloids (Normal Saline vs Hartmann's vs 5%D) vs colloids (Gelofusine, Albumin); indications ★★★■■ ×6 Total Parenteral Nutrition (Anaesthesia context) – indications; complications; monitoring ★★★■■ ×5 Haemorrhage Classification – Class I–IV (% blood loss, HR, BP, RR, UO, GCS); management per class ★★★■■ ×5 Colloid vs Crystalloid – comparison; Starling forces; pros/cons of colloids in sepsis (SAFE trial) ★★★■■ ×4
Reading File
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Excellent - 3 anaesthesiology textbooks available (Miller's, Barash's, Morgan & Mikhail's). Let me search them directly:
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Good - I have strong source confirmation. Now I have enough to write comprehensive exam answers. Let me deliver all topics systematically with visuals.Here is your complete, exam-ready anaesthesia answer guide. Sourced from Miller's Anesthesia 10e, Morgan & Mikhail 7e, and Barash's Clinical Anesthesia 9e.
🏥 FINAL MBBS ANAESTHESIA - COMPLETE EXAM GUIDE
SECTION 1: PREOPERATIVE ASSESSMENT
⭐⭐⭐⭐⭐ 1. ASA Physical Status Classification (×8)
What it is: A system by the American Society of Anesthesiologists to risk-stratify patients before anaesthesia and surgery.
| ASA | Definition | Clinical Examples |
|---|---|---|
| I | Normal healthy patient | No diseases, non-smoker, BMI <30 |
| II | Mild systemic disease | Well-controlled DM/HTN, smoker, BMI 30-40, pregnancy |
| III | Severe systemic disease | Poorly controlled DM/HTN, COPD, morbid obesity (BMI >40), active hepatitis, ESRD on dialysis, CAD |
| IV | Life-threatening disease | Recent MI (<3mo), CVA, severe valve disease, sepsis |
| V | Moribund - not expected to survive without surgery | Ruptured AAA, massive trauma, intracranial bleed with herniation |
| VI | Brain-dead donor for organ harvest | - |
| E suffix | Emergency surgery added to any class | ASA IIE, IIIE, etc. |
🧠 Reasoning: Higher ASA = higher perioperative mortality risk. ASA I/II = low risk. ASA III = intermediate. ASA IV/V = high risk - needs ICU backup, senior anaesthetist.
Mnemonic: "Healthy → Mild → Severe → Life-threatening → Moribund → Dead donor"
⭐⭐⭐⭐⭐ 2. Preoperative Airway Assessment (×8)
Goal: Predict a DIFFICULT AIRWAY before induction to avoid "can't intubate, can't oxygenate" crisis.
Mallampati Classification (most tested!)
Assessed with patient seated, mouth fully open, tongue protruded, no phonation:
| Class | What you see | Difficulty |
|---|---|---|
| I | Soft palate, fauces, uvula, pillars visible | Easy |
| II | Soft palate, fauces, uvula visible | Easy |
| III | Soft palate and base of uvula visible | Difficult |
| IV | Only hard palate visible | Very Difficult |
🧠 Key point: Class III/IV = predicted difficult intubation. But Mallampati alone is not sufficient - use with other predictors.
Other Airway Predictors (LEMON mnemonic)
| Letter | Test | Normal Value |
|---|---|---|
| L | Look externally (obesity, short neck, receding chin, large tongue) | - |
| E | Evaluate 3-3-2 rule | 3 finger mouth opening, 3 finger hyoid-chin, 2 finger thyroid-floor |
| M | Mallampati | Class I/II = easy |
| O | Obstruction/Obesity | - |
| N | Neck mobility | Can patient flex/extend? |
| Test | Normal | Difficult if |
|---|---|---|
| Mouth opening | >4 cm (3 fingers) | <3 cm |
| Thyromental distance | >6.5 cm | <6 cm |
| Neck mobility | Normal flexion/extension | Restricted |
| Sternomental distance | >12.5 cm | <12 cm |
Difficult Airway Algorithm (DAA)
PREDICTED DIFFICULT AIRWAY?
↓
Awake intubation (fibreoptic) preferred
↓
If GA essential → Have plan A, B, C
Plan A: Direct laryngoscopy
Plan B: Video laryngoscopy / LMA
Plan C: Surgical airway (cricothyrotomy)
↓
"CALL FOR HELP EARLY"
⭐⭐⭐⭐⭐ 3. Fasting Guidelines (×7)
Rule: "2-4-6-8" (ASA 2017 Guidelines)
| Ingested Material | Minimum Fast |
|---|---|
| Clear fluids (water, black tea/coffee, juices without pulp) | 2 hours |
| Breast milk | 4 hours |
| Light meal (toast + clear fluid) / Formula milk | 6 hours |
| Heavy/fatty meal (fried food, meat) | 8 hours |
🧠 Reasoning: Risk of pulmonary aspiration of gastric contents (Mendelson's syndrome). Gastric volume >25 mL + pH <2.5 = danger zone.
RSI Indication: When fasting guidelines NOT met (full stomach) → Rapid Sequence Induction:
- Pre-oxygenate → Cricoid pressure (Sellick's manoeuvre) → Suxamethonium 1.5 mg/kg → Intubate → Release cricoid after cuff inflated
⭐⭐⭐ 4. Pre-Anaesthetic Checkup (PAC) (×6)
Purpose: Identify and optimise patient risk before surgery.
Checklist:
- History: Allergies, previous anaesthesia problems, medications, family history (malignant hyperthermia!)
- Examination: Vitals, airway, cardiovascular, respiratory, neurological
- Investigations: CBC, RFT, LFT, ECG (>40yrs), CXR, coagulation (if regional planned), blood glucose
- Informed Consent: Risks of GA/RA explained including awareness, nerve damage, PONV, death
Premedication Drugs:
| Drug | Purpose | Dose/Route |
|---|---|---|
| Midazolam | Anxiolysis, amnesia | 0.02-0.05 mg/kg IV/IM |
| Glycopyrrolate | Antisialagogue (dries secretions), prevents bradycardia | 0.2 mg IV/IM |
| Ranitidine/Pantoprazole | Reduce gastric acidity and volume | Oral night before + morning |
| Metoclopramide | Prokinetic - speeds gastric emptying | 10 mg IV |
| Ondansetron | Antiemetic - PONV prophylaxis | 4-8 mg IV |
⭐⭐⭐ 5. Cardiovascular & Respiratory Complications of GA (×4)
| Complication | Cause | Management |
|---|---|---|
| Hypotension | Vasodilation from agents, blood loss | IV fluids, vasopressors (ephedrine, phenylephrine) |
| Hypertension | Light anaesthesia, laryngoscopy | Deepen anaesthesia, labetalol, GTN |
| Bradycardia | Vagal stimulation, neostigmine | Atropine 0.6 mg IV |
| Arrhythmias | Hypoxia, hypercapnia, volatile agents | Correct cause, amiodarone/lidocaine |
| Laryngospasm | Airway stimulation during light anaesthesia | CPAP, suxamethonium 0.5 mg/kg |
| Bronchospasm | Asthma, aspiration | Salbutamol, deepening anaesthesia, adrenaline if severe |
| Hypoxia | Airway obstruction, V/Q mismatch, atelectasis | O2, repositioning, PEEP |
| Awareness | Inadequate depth | Prevention: BIS monitoring, adequate MAC |
SECTION 2: GENERAL ANAESTHESIA
⭐⭐⭐⭐⭐ 6. IV Induction Agents (×9)
| Feature | Propofol | Thiopentone | Ketamine |
|---|---|---|---|
| Class | Alkylphenol | Barbiturate | Phencyclidine derivative |
| Dose | 1.5-2.5 mg/kg IV | 3-5 mg/kg IV | 1-2 mg/kg IV |
| Onset | 30 sec | 30 sec | 30-60 sec |
| Duration | 5-10 min | 5-10 min | 10-15 min |
| BP effect | ↓↓ Hypotension | ↓ Moderate | ↑ Hypertension |
| HR effect | ↓ Bradycardia | Reflex ↑ | ↑↑ Tachycardia |
| Resp | ↓↓ Apnoea common | ↓ Apnoea | Maintained (bronchodilator) |
| ICP | ↓ (good for neuro) | ↓ | ↑ (avoid in head injury) |
| IOP | ↓ | ↓ | ↑ |
| Antiemetic? | Yes (sub-anaesthetic dose) | No | No (causes PONV) |
| Pain on injection | Yes | No | No |
| Special uses | TIVA, sedation, daycare | Rapid induction, status epilepticus | Haemodynamically unstable, paediatrics, burns, analgesia, asthma |
| Contraindications | Egg/soy allergy, hypotension | Acute intermittent porphyria, asthma | Hypertension, ischaemic heart disease, raised ICP |
🧠 Key Points:
- Propofol = agent of choice for TIVA (Total IV Anaesthesia). Milk-white emulsion in soybean oil/egg lecithin.
- Thiopentone = ultrashort-acting barbiturate. Causes acute porphyria crisis.
- Ketamine = "dissociative anaesthesia" - produces analgesia + amnesia + immobility. Maintains airway reflexes. Causes emergence delirium (give midazolam with it).
⭐⭐⭐⭐⭐ 7. Volatile Anaesthetic Agents & MAC (×7)
MAC (Minimum Alveolar Concentration): The alveolar concentration of a volatile agent at 1 atmosphere that prevents movement in 50% of patients to a standard surgical stimulus. Lower MAC = more potent.
| Agent | MAC (%) | B/G Coeff | Induction | Pungency | CV Effects | Resp Effects | Special |
|---|---|---|---|---|---|---|---|
| Isoflurane | 1.15 | 1.4 | Slow | Pungent (not for inhalation induction) | ↓BP, coronary steal | Respiratory depression | Cheapest |
| Sevoflurane | 2.0 | 0.65 | Fast | Non-pungent (inhalation induction in kids) | ↓BP (mild) | Respiratory depression | Agent of choice for inhalation induction; produces Compound A (nephrotoxic in rats) |
| Desflurane | 6.0 | 0.42 | Fastest | Very pungent (NOT for induction) | ↓BP, ↑HR | Respiratory depression | Fastest emergence; needs special heated vaporiser |
| Halothane | 0.75 | 2.4 | Slow | Non-pungent | ↓BP, ↓HR, sensitises myocardium to catecholamines | Respiratory depression | Halothane hepatitis; rarely used now |
| N₂O | 105% | 0.47 | - | Non-pungent | Minimal | Minimal | Analgesic; expands gas cavities |
🧠 Blood:Gas Coefficient: Lower = faster induction/recovery (agent less soluble in blood, reaches brain faster).
MAC Modifiers:
| Increases MAC (need more) | Decreases MAC (need less) |
|---|---|
| Hyperthermia | Hypothermia |
| Chronic alcohol use | Opioids, benzodiazepines |
| Hyperthyroidism | Old age |
| Red hair | Pregnancy |
⭐⭐⭐⭐⭐ 8. Muscle Relaxants (×7)
Suxamethonium (Succinylcholine) - Depolarising
- Mechanism: Mimics ACh at NMJ → sustained depolarisation → fasciculations → flaccid paralysis
- Dose: 1-1.5 mg/kg IV
- Onset: 60 sec (fastest!) | Duration: 5-10 min (shortest!)
- Metabolised by: Plasma cholinesterase (pseudocholinesterase)
Phase I Block: Initial depolarising block - no reversal needed (short duration)
Phase II Block: With repeated/large doses - becomes non-depolarising-like; can reverse with neostigmine
Contraindications (MNEMONIC: "BHUCKS"):
B - Burns (>48 hours after)
H - Hyperkalaemia / Hyperkalemia states
U - Upper/Lower Motor Neuron lesions (crush injury, denervation)
C - Crush injuries (>24h)
K - Known pseudocholinesterase deficiency
S - Spinal cord injury, Stroke (>24h)
Also: Malignant hyperthermia susceptibility, raised IOP/ICP (caution), myopathies
Side effects: Fasciculations, K⁺ rise (0.5 mEq/L normal; dangerous in above conditions), bradycardia (give atropine pre-treatment), malignant hyperthermia trigger, suxamethonium apnoea
Non-Depolarising Muscle Relaxants
| Drug | Dose | Onset | Duration | Elimination | Notes |
|---|---|---|---|---|---|
| Rocuronium | 0.6 mg/kg (RSI: 1.2 mg/kg) | 60-90s | 30-60 min | Hepatic | RSI alternative when sux CI; reversed by Sugammadex |
| Vecuronium | 0.1 mg/kg | 3-4 min | 25-40 min | Hepatic/Biliary | Cardiovascular stable, safe in renal disease |
| Atracurium | 0.5 mg/kg | 3-5 min | 20-35 min | Hofmann elimination | Safe in renal AND hepatic failure; histamine release; produces laudanosine |
| Cisatracurium | 0.15 mg/kg | 5 min | 40-60 min | Hofmann | Like atracurium but no histamine release |
| Pancuronium | 0.1 mg/kg | 3-5 min | 60-90 min | Renal (80%) | Long-acting; causes tachycardia |
Reversal: Neostigmine 0.05 mg/kg + Glycopyrrolate 0.01 mg/kg (or Atropine 0.02 mg/kg)
OR Sugammadex (reverses rocuronium/vecuronium directly, no need for anticholinergic)
⭐⭐⭐⭐⭐ 9. Neostigmine Reversal (×7)
Mechanism: Acetylcholinesterase (AChE) inhibitor → prevents breakdown of ACh → ACh accumulates at NMJ → competes with non-depolarising relaxant → reversal of block.
Non-depolarising NMR blocks Nicotinic NMJ receptor
↓
Neostigmine inhibits AChE enzyme
↓
ACh builds up → displaces NDMR from receptor
↓
Muscle contraction restored
Why add Anticholinergic?
ACh builds up at ALL cholinergic receptors - not just nicotinic (NMJ) but also muscarinic:
| Muscarinic Side Effect | Prevented by |
|---|---|
| Bradycardia | Atropine / Glycopyrrolate |
| Bronchospasm | Same |
| Increased secretions | Glycopyrrolate preferred (does NOT cross BBB) |
| PONV, bowel motility ↑ | Same |
| Miosis | Same |
Atropine vs Glycopyrrolate with Neostigmine:
- Glycopyrrolate is preferred (quaternary ammonium, does NOT cross BBB → no CNS effects, longer duration, better antisialagogue)
- Atropine - faster onset but crosses BBB → CNS effects possible
Dose: Neostigmine 0.05 mg/kg + Glycopyrrolate 0.01 mg/kg IV (given together in same syringe)
Requirement: Must have SOME neuromuscular recovery before giving (TOF ratio >0.1). Check with nerve stimulator.
⭐⭐⭐ 10. Nitrous Oxide (N₂O) (×6)
| Property | Detail |
|---|---|
| MAC | 105% (needs hyperbaric chamber alone) |
| Blood:Gas | 0.47 (fast onset/offset) |
| Analgesic | Yes - "laughing gas" |
| Amnesic | Yes |
| Muscle relaxant | No |
Advantages:
- Rapid onset/offset
- Analgesic (used in dentistry, labour - Entonox = 50% N₂O + 50% O₂)
- Reduces MAC of other volatile agents (allows lower doses)
- No cardiac depression
Disadvantages/Contraindications (MNEMONIC: "BABE PNC"):
| Problem | Reason |
|---|---|
| Bowel obstruction | N₂O expands gas-filled cavities (30x more soluble than N₂) |
| Air embolism | Expands air emboli → fatal |
| Bullous emphysema, pneumothorax | Cavity expansion |
| Ear surgery (closed cavity) | Middle ear pressure rise |
| Pneumocephalus | Expands intracranial air |
| Neonates | |
| Cobalamin (B12) inactivation | Irreversibly oxidises B12 → methionine synthase inhibition → megaloblastic anaemia, subacute combined degeneration |
PONV: Strong emetogenic - contributes to postoperative nausea/vomiting.
⭐⭐⭐ 11. Premedication Drugs (×5)
| Drug | Class | Purpose | Dose |
|---|---|---|---|
| Midazolam | Benzodiazepine | Anxiolysis, amnesia, sedation | 0.02-0.05 mg/kg IV/IM; 0.5 mg/kg oral (peds) |
| Glycopyrrolate | Anticholinergic | Antisialagogue, prevent bradycardia | 0.2 mg IV/IM |
| Ranitidine | H2 blocker | ↓ gastric acid volume & pH | 150 mg oral night before |
| Metoclopramide | Prokinetic | ↑ gastric emptying, antiemetic | 10 mg IV |
| Ondansetron | 5-HT3 antagonist | PONV prophylaxis | 4-8 mg IV |
| Morphine/Pethidine | Opioid | Analgesia, sedation | 0.1 mg/kg IM |
| Atropine | Anticholinergic | Antisialagogue, prevent bradycardia (peds) | 0.02 mg/kg |
⭐⭐⭐ 12. Opioids (×4)
| Feature | Morphine | Fentanyl | Tramadol |
|---|---|---|---|
| Potency | 1 (reference) | 100x morphine | 0.1x morphine |
| Onset | Slow (15-30 min) | Rapid (1-2 min IV) | 30-60 min |
| Duration | 4-6 hours | 30-60 min IV | 4-6 hours |
| Route | IV/IM/SC/epidural | IV/transdermal/intranasal | IV/oral |
| Histamine release | Yes | No | No |
| Cardiovascular | ↓HR, ↓BP (histamine) | Bradycardia (no histamine) | Minimal |
| Special | Active metabolite (M6G) accumulates in renal failure | TIVA, cardiac surgery, labour analgesia | Weak opioid + SNRI; reduces seizure threshold |
Opioid Side Effects (all): NRVDPC
- Nausea/vomiting
- Respiratory depression (↓ RR, miosis)
- Vomiting, constipation
- Drowsiness
- Pruritus (morphine > fentanyl)
- Confusion/urinary retention
Reversal: Naloxone 0.4-2 mg IV (pure opioid antagonist, displaces opioid from receptor). Short half-life (30-90 min) - may need repeat dosing or infusion.
SECTION 3: REGIONAL ANAESTHESIA
⭐⭐⭐⭐⭐ 13. Spinal vs Epidural Anaesthesia (×9)
| Feature | Spinal (Intrathecal) | Epidural |
|---|---|---|
| Site of injection | Subarachnoid space (inside dura) | Epidural space (outside dura) |
| Level | L3/4 or L4/5 (below conus at L1/L2) | Any level (lumbar, thoracic, cervical) |
| Drug volume | Small (1.5-3.5 mL) | Large (10-20 mL) |
| Onset | Fast (5-10 min) | Slow (15-20 min) |
| Drug concentration | Dilute in CSF | Concentrated |
| Catheter? | No (single shot) | Yes (catheter for continuous) |
| Dural puncture? | Deliberate | Accidental = PDPH complication |
| Block spread | Controlled by baricity, position | Controlled by volume, gravity |
| Level of block | Up to T4 for abdominal, T10 for LSCS | Adjustable |
| Failure rate | Low | Higher |
Drugs used in Spinal:
- Bupivacaine 0.5% hyperbaric (heavy) - 2-3 mL for LSCS
- Fentanyl 25 mcg intrathecal - added for analgesia
- Adrenaline - prolongs block
Contraindications to BOTH:
| Absolute | Relative |
|---|---|
| Patient refusal | Coagulopathy (INR >1.5, platelets <80,000) |
| Infection at site | Anticoagulants (LMWH within 12h) |
| Raised ICP | Severe hypovolaemia |
| Severe coagulopathy | Neurological disease |
⭐⭐⭐⭐⭐ 14. Complications of Spinal Anaesthesia (×7)
COMPLICATIONS OF SPINAL ANAESTHESIA
IMMEDIATE EARLY LATE
--------- ----- ----
Hypotension PDPH Backache
Total spinal Urinary retention Nerve damage (rare)
High spinal Nausea/vomiting Cauda equina syndrome
Failed block Headache Meningitis (rare)
Bradycardia Shivering
| Complication | Mechanism | Management |
|---|---|---|
| Hypotension (most common) | Sympathetic block → vasodilation + ↓CO | Pre-load 500-1000mL IV fluid; Ephedrine 5-10mg IV (mixed α+β, preferred in obstetrics); Phenylephrine (pure α, vasopressor of choice in spinal for LSCS now); left lateral tilt in pregnancy |
| PDPH (Post-Dural Puncture Headache) | CSF leak from dural hole → ↓CSF pressure → traction on meninges | Conservative: bed rest, oral fluids, analgesia, caffeine; Epidural Blood Patch (gold standard - 20mL autologous blood seals the leak) |
| High/Total Spinal | Block reaches cervical/brainstem | Stop surgery, IPPV, vasopressors, reassure patient |
| Urinary Retention | Sacral (S2-4) block | Catheterisation |
| Bradycardia | Block of cardioaccelerator fibres (T1-T4) | Atropine 0.6 mg IV |
PDPH Features:
- Postural headache (worse sitting/standing, relieved lying)
- Frontal/occipital
- ± Neck stiffness, diplopia, tinnitus
- Prevented by: small gauge needle (25-27G), pencil-point (Whitacre/Sprotte) needle
⭐⭐⭐ 15. Local Anaesthetics (×6)
Mechanism: Block voltage-gated Na⁺ channels → prevent depolarisation → nerve conduction blocked.
Blocks in order of sensitivity: Autonomic (B fibres) → Sensory (cold, pain, touch, pressure) → Motor (A fibres)
| Feature | Lidocaine (Lignocaine) | Bupivacaine |
|---|---|---|
| Potency | Less potent | 4x more potent |
| Duration | Short (1-2h) | Long (3-8h) |
| Safe dose | 3 mg/kg plain; 7 mg/kg with adrenaline | 2 mg/kg plain; 2.5 mg/kg with adrenaline |
| Max dose (70kg) | 210 mg plain, 490 mg with adrenaline | 140 mg |
| Onset | Faster | Slower |
| Uses | Topical, IV regional (Bier's block), infiltration, spinal, epidural | Spinal (heavy bupivacaine), epidural, peripheral nerve blocks |
| Toxicity | CNS (tinnitus→seizures→coma) then CVS | Severe cardiotoxicity (VF, refractory to resuscitation) - treat with 20% Intralipid |
Adrenaline added to LA:
- Causes local vasoconstriction → slows absorption → prolongs duration, reduces toxicity, reduces bleeding
- DO NOT use with adrenaline in: Ring blocks (digits, penis, tip of nose, ear) - risk of ischaemia/gangrene
LA Toxicity Treatment: Stop injection → O2 → IV access → for CVS toxicity → 20% Intralipid 1.5 mL/kg bolus then infusion
⭐⭐⭐ 16. Brachial Plexus Block (×5)
Roots: C5, C6, C7, C8, T1
Approaches Comparison:
| Approach | Level Blocked | Best For | Risk |
|---|---|---|---|
| Interscalene | C5-C7 (shoulder) | Shoulder surgery | Phrenic nerve palsy (100%), Horner's syndrome, vertebral artery injection, NOT for bilateral - apnoea risk |
| Supraclavicular | C5-T1 (whole arm) | Upper limb surgery (most complete) | Pneumothorax (highest risk), subclavian artery puncture |
| Infraclavicular | Cords | Elbow/forearm/hand | Less pneumothorax risk |
| Axillary | Terminal branches | Hand/forearm | Musculocutaneous nerve often missed; axillary artery puncture |
🧠 Memory: "I Saw Some Axe" = Interscalene → Supraclavicular → Infraclavicular → Axillary (proximal to distal)
⭐⭐⭐ 17. Epidural Analgesia (×5)
Technique:
- Sitting or lateral decubitus position
- L3/4 or L4/5 interspace (lumbar epidural)
- Loss of resistance technique (LOR) - to saline or air
- Epidural space identified - catheter threaded 3-5 cm
- Test dose: 3 mL of 1% lignocaine + adrenaline (if intravascular → tachycardia; if intrathecal → rapid spinal block)
- Top up with 0.1% bupivacaine + fentanyl
Advantages:
- Continuous analgesia (catheter)
- Labour analgesia (gold standard)
- Post-op pain relief (thoracic/abdominal)
- Reduces stress response to surgery
- Allows dose titration
Complications:
- Hypotension, PDPH (if accidental dural puncture)
- Epidural haematoma (rare, catastrophic - needs urgent MRI + decompression)
- Epidural abscess
- Inadequate/patchy block
- Total spinal (if accidental intrathecal injection of epidural dose)
SECTION 4: EMERGENCY / RESUSCITATION
⭐⭐⭐⭐⭐ 18. Adult ACLS Algorithm (×9)
CARDIAC ARREST
↓
Start CPR (100-120/min, 5-6cm depth)
High-flow O2 | IV/IO access
↓
Rhythm check (defibrillator)
↙ ↘
SHOCKABLE NON-SHOCKABLE
VF / pulseless VT PEA / Asystole
↓ ↓
SHOCK (biphasic Continue CPR
200J → 300J → 360J) Adrenaline 1mg IV
↓ ASAP then q3-5min
Resume CPR 2min ↓
↓ Look for 4H/4T
Adrenaline 1mg IV
(after 3rd shock,
then q3-5min)
↓
If VF/VT persists:
Amiodarone 300mg IV
(then 150mg if needed)
4H/4T Reversible Causes:
| 4H | 4T |
|---|---|
| Hypoxia | Tension pneumothorax |
| Hypovolaemia | Tamponade (cardiac) |
| Hypo/Hyperkalaemia & metabolic | Toxins (drugs/poisons) |
| Hypothermia | Thrombosis (PE or MI) |
Drugs in ACLS:
| Drug | Dose | Indication |
|---|---|---|
| Adrenaline (Epinephrine) | 1 mg IV every 3-5 min | All arrests (shockable: after 3rd shock; non-shockable: ASAP) |
| Amiodarone | 300 mg IV bolus, then 150 mg | Refractory VF/pulseless VT |
| Lidocaine | 1 mg/kg IV | Alternative if amiodarone unavailable |
| MgSO₄ | 2g IV | Torsades de Pointes, hypomagnesaemia |
| Sodium Bicarbonate | 1 mEq/kg | Hyperkalaemia, TCA overdose, prolonged arrest |
| Atropine | No longer in shockable/non-shockable routinely (removed from guidelines 2010) | Symptomatic bradycardia only |
| Calcium gluconate | 10 mL of 10% | Hyperkalaemia, CCB toxicity |
⭐⭐⭐⭐⭐ 19. CPR - High Quality (×8)
"High-Quality CPR is the most important intervention in cardiac arrest"
| Parameter | Target |
|---|---|
| Rate | 100-120 compressions/min |
| Depth | 5-6 cm (adults); 4-5 cm (children); 4 cm (infants) |
| Recoil | Allow FULL chest recoil between compressions |
| Interruptions | Minimise - pause <10 sec for rhythm check |
| Hand position | Lower half of sternum, heel of hand |
| Compression:ventilation | 30:2 (before advanced airway); continuous after intubation |
| Ventilation | Avoid hyperventilation; 1 breath over 1 second |
| Switch compressor | Every 2 minutes (fatigue) |
Adrenaline timing:
- Non-shockable: 1 mg IV as soon as IV access - repeat every 3-5 min
- Shockable: 1 mg IV after 3rd shock - then every 3-5 min
- Mechanism: α1 → vasoconstriction → ↑coronary perfusion pressure and cerebral perfusion
Post-ROSC Care:
- 12-lead ECG → PCI if ST elevation
- Target O₂ sat 94-98% (avoid hyperoxia)
- Target CO₂ normocapnia
- Temperature management (TTM): 32-36°C for 24h
- BP target: MAP >65 mmHg
⭐⭐⭐⭐⭐ 20. Rapid Sequence Induction (RSI) (×7)
Definition: Technique of rapid induction + intubation to minimise risk of pulmonary aspiration in patients with full stomach.
Indications:
- Full stomach (not adequately fasted)
- Bowel obstruction / ileus
- Hiatus hernia / GORD
- Pregnancy (>16 weeks)
- Trauma (unknown fasting status)
- Obesity
Steps of RSI (7 Ps):
1. PREPARATION - check equipment, IV access, pre-draw drugs
2. PRE-OXYGENATION - 100% O2 for 3-5 min (denitrogenation - fills FRC with O2)
3. PRETREATMENT - (optional) Lignocaine (↓ICP), Atropine (peds), Fentanyl
4. PARALYSIS + INDUCTION - simultaneously
- Propofol 1.5-2 mg/kg (or Thiopentone 4-5 mg/kg, or Ketamine if haemodynamically unstable)
- + Suxamethonium 1.5 mg/kg IV (drug of choice - fastest onset/offset)
5. PROTECTION of airway (Cricoid pressure - Sellick's manoeuvre)
6. PLACEMENT of tube (intubate when jaw relaxed, cords visible)
7. POST-INTUBATION - confirm placement (EtCO2, chest rise), release cricoid, inflate cuff
Modified RSI (when suxamethonium contraindicated):
- Use Rocuronium 1.2 mg/kg (high dose gives similar conditions to sux within 60 sec)
- Reversal: Sugammadex 16 mg/kg (immediately reverses even full paralysis)
Suxamethonium in RSI:
- Causes fasciculations (can pre-treat with non-depolarising agent - "defasciculation dose")
- K⁺ rises 0.5 mEq/L normally → dangerous in burns, crush, denervation (use rocuronium instead)
SECTION 5: FLUIDS & NUTRITION
⭐⭐⭐ 21. IV Fluids - Crystalloids vs Colloids (×6)
Crystalloids:
| Fluid | Na⁺ (mEq/L) | Cl⁻ | Glucose | Osmolarity | pH | Use |
|---|---|---|---|---|---|---|
| Normal Saline (0.9% NaCl) | 154 | 154 | 0 | 308 | 5.7 | Volume expansion, drug dilution, hypernatraemia risk with large volumes; causes hyperchloraemic acidosis |
| Hartmann's (Ringer's Lactate) | 130 | 109 | 0 | 273 | 6.5 | Most physiological - preferred for surgical patients, trauma; lactate metabolised by liver to bicarbonate |
| 5% Dextrose | 0 | 0 | 50g/L | 252 | 4.0 | Maintenance, hypoglycaemia; distributes to ALL compartments (1/12 stays intravascular); NOT for volume replacement |
| Dextrose Saline (0.18% NaCl + 4% D) | 30 | 30 | 40g/L | 284 | - | Maintenance in children |
Colloids:
| Fluid | Oncotic Pressure | Duration in circulation | Notes |
|---|---|---|---|
| Gelofusine (gelatin) | Similar to plasma | 4-6 hours | Allergic reactions; does NOT affect coagulation |
| Albumin 4.5-5% | High | 12-24 hours | SAFE trial: safe in sepsis, but no better than saline; expensive |
| Hydroxyethyl Starch (HES) | High | 6-12 hours | AVOID in sepsis/AKI - renal failure, coagulopathy risk |
| Dextran | High | 6-12 hours | Interferes with cross-matching; antithrombotic |
Starling Forces - why colloids stay intravascular:
- Oncotic pressure of colloid > interstitial → draws water into vessel
- Crystalloids have no oncotic pressure → distribute freely (only 20-25% stays intravascular)
⭐⭐⭐ 22. Haemorrhage Classification (×5)
| Class | Blood Loss | % Volume | HR | BP | RR | UO (mL/hr) | CNS/GCS |
|---|---|---|---|---|---|---|---|
| Class I | <750 mL | <15% | <100 | Normal | 14-20 | >30 | Normal/anxious |
| Class II | 750-1500 mL | 15-30% | 100-120 | Normal (↑DBP) | 20-30 | 20-30 | Anxious |
| Class III | 1500-2000 mL | 30-40% | 120-140 | ↓↓ | 30-40 | 5-15 | Confused |
| Class IV | >2000 mL | >40% | >140 | ↓↓↓ | >35 | <5 | Lethargic/unconscious |
Management by Class:
| Class | Management |
|---|---|
| I | Crystalloids (1:1 replacement) |
| II | Crystalloids + consider blood |
| III | Blood products, massive transfusion protocol consideration |
| IV | Immediate surgery, 1:1:1 pRBC:FFP:Platelets (damage control resuscitation), permissive hypotension (MAP 50-65) |
🧠 Rule of Threes: Replace 3 mL crystalloid for every 1 mL blood lost (due to redistribution)
⭐⭐⭐ 23. Colloid vs Crystalloid Debate (×4)
| Aspect | Crystalloid | Colloid |
|---|---|---|
| Cost | Cheap | Expensive |
| Intravascular retention | Poor (20-25%) | Good (70-80%) |
| Volume needed | 3-4x more | Less |
| Oedema | More (dilutes oncotic pressure) | Less |
| Coagulation | No effect | HES/Dextran impair coagulation |
| Renal toxicity | No | HES → AKI |
| Allergy | Nil | Gelatin/Dextran risk |
SAFE Trial (NEJM 2004): 4% albumin vs Normal Saline in ICU - NO significant difference in mortality. (Exception: albumin may worsen outcomes in TBI; may benefit severe sepsis/SBP)
Current Recommendation: Crystalloids (Hartmann's/Ringer's Lactate) as first-line for resuscitation. Colloids (albumin) as second-line for persistent hypoalbuminaemia or failure to respond to crystalloids.
⭐⭐⭐ 24. Total Parenteral Nutrition (TPN) (×5)
Definition: Complete nutrition delivered intravenously, bypassing the GI tract.
Indications (GI tract non-functional/inaccessible):
- Prolonged ileus, intestinal obstruction
- Short bowel syndrome
- High-output fistulae
- Severe pancreatitis
- Inflammatory bowel disease
- Post-major GI surgery
Components of TPN:
- Carbohydrates: Dextrose (main energy)
- Protein: Amino acids (branched-chain)
- Fat: Lipid emulsions
- Electrolytes: Na, K, Mg, Ca, PO4
- Vitamins + Trace elements
Route: Central venous catheter (high osmolarity - 1800-2000 mOsm/L - damages peripheral veins)
Complications (MNEMONIC: "CIMETS"):
| Type | Complication |
|---|---|
| Catheter | Pneumothorax, haemothorax, air embolism, infection (CLABSI) |
| Infection | Line sepsis (most common serious complication) |
| Metabolic | Hyperglycaemia (most common), electrolyte abnormalities (hypo PO4, K, Mg), fatty liver |
| Refeeding Syndrome | If severely malnourished - sudden ↓PO4, K, Mg → cardiac arrhythmias, respiratory failure |
| Technical | Air embolism, occlusion |
Monitoring: Daily: glucose, electrolytes, fluid balance. Weekly: LFT, TFT, albumin, trace elements.
📋 QUICK REVISION SUMMARY TABLE
| Topic | Key Number/Fact to Remember |
|---|---|
| ASA I-VI | "E" suffix for emergency |
| Mallampati | III/IV = difficult airway |
| Fasting | 2h clear fluids, 6h solids |
| Propofol dose | 1.5-2.5 mg/kg |
| Ketamine | Only agent that ↑BP |
| Suxamethonium onset | 60 sec, fastest |
| MAC of isoflurane | 1.15% |
| Neostigmine | Give with glycopyrrolate |
| Spinal level | L3/4 or L4/5 |
| PDPH treatment | Blood patch (gold standard) |
| Bupivacaine max dose | 2 mg/kg |
| CPR rate | 100-120/min |
| CPR depth | 5-6 cm adults |
| Adrenaline in ACLS | 1 mg IV q3-5 min |
| Amiodarone | 300 mg for shockable rhythm |
| RSI sux dose | 1.5 mg/kg |
| Class IV haemorrhage | >40% blood loss |
| SAFE trial | Albumin = saline in ICU |
Sources: Miller's Anesthesia 10e, Morgan & Mikhail's Clinical Anesthesiology 7e, Barash's Clinical Anesthesia 9eAll 24 high-yield topics covered! Here's what you got:
What's inside this guide:
| Section | Topics Covered |
|---|---|
| Preoperative Assessment | ASA I-VI, Mallampati + LEMON, Fasting 2-4-6-8, PAC checklist, CV/Resp complications |
| General Anaesthesia | Propofol vs Thiopentone vs Ketamine, MAC + volatiles, Suxamethonium (Phase I/II, contraindications), NDMRs comparison, Neostigmine mechanism, N₂O pros/cons, Premeds, Opioids |
| Regional Anaesthesia | Spinal vs Epidural full comparison, PDPH + blood patch, Hypotension management, LAs (Lidocaine vs Bupivacaine + Intralipid), Brachial plexus 4 approaches, Epidural technique |
| Emergency/Resuscitation | ACLS shockable vs non-shockable algorithm, 4H/4T, drug doses, High-quality CPR parameters, RSI 7 steps + modified RSI |
| Fluids & Nutrition | Crystalloids comparison, Colloids, Haemorrhage Class I-IV table, Colloid vs Crystalloid + SAFE trial, TPN indications + complications |
Tips for exam:
- Learn the tables - examiners love comparisons (Spinal vs Epidural, Propofol vs Ketamine, Class I-IV)
- Know the mnemonics - LEMON, BHUCKS, 4H/4T
- Know the doses - Suxamethonium 1.5 mg/kg, Adrenaline 1 mg, Bupivacaine max 2 mg/kg
- The "why" matters - e.g., why glycopyrrolate with neostigmine, why blood patch for PDPH
Ask me to expand any topic, create flashcards, or explain a mechanism in more depth!
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