---

Anesthesia: Overview & Types

---

1. General Anesthesia (GA)

Two routes of delivery

Inhalational Agents

• Blood/gas solubility coefficient - determines speed of induction/emergence. Lower solubility = faster onset. Nitrous oxide and desflurane have low solubility; halothane has high solubility.
• MAC (Minimum Alveolar Concentration) - the dose at which 50% of patients do not move to surgical stimulation. Higher MAC = less potent drug.

Key IV Induction Agents

• Propofol - most widely used; rapid onset and offset even after prolonged infusion; causes hypotension and apnea; can cause propofol infusion syndrome (cardiomyopathy, metabolic acidosis, rhabdomyolysis) at high doses.
• Midazolam - benzodiazepine; hypnotic, amnestic, anxiolytic, anticonvulsant; acts via GABA-A receptors.
• Ketamine - NMDA receptor antagonist; dissociative anesthesia; preserves airway reflexes and spontaneous breathing; bronchodilator; useful in hemodynamically unstable patients.
• Etomidate - minimal cardiovascular depression; favored in cardiac or trauma patients; inhibits adrenal steroidogenesis with prolonged use.

---

2. Regional Anesthesia

A. Neuraxial Blocks (Central Regional)

Spinal Anesthesia (Subarachnoid Block)

• Local anesthetic is injected directly into the subarachnoid (intrathecal) space (CSF), typically at L3-L4 or L4-L5.
• Onset is rapid (minutes); provides dense motor, sensory, and sympathetic block.
• Level of block depends on drug baricity, patient position, and dose.
• Common uses: lower limb surgery, hip/knee arthroplasty, cesarean section, TURP.
• Risk: hypotension from sympathetic block, post-dural puncture headache (PDPH), urinary retention, high/total spinal.

Epidural Anesthesia

• Local anesthetic is injected into the epidural space (outside the dura).
• Onset is slower than spinal; level is more titratable via catheter.
• Can be combined with spinal (combined spinal-epidural, CSE) for surgery + extended postoperative analgesia.
• Common for obstetric labor analgesia, thoracic surgery, colorectal procedures.

Caudal Anesthesia

• Entry to the epidural space via the sacral hiatus; common in pediatric surgery.

B. Peripheral Nerve Blocks

• Brachial plexus blocks (interscalene, supraclavicular, axillary) - upper limb surgery
• Femoral / adductor canal / sciatic blocks - lower limb surgery
• TAP block (transversus abdominis plane) - abdominal wall analgesia
• Wrist blocks, digital blocks - hand and finger procedures
• Infraorbital / trigeminal blocks - facial procedures

C. Intravenous Regional Anesthesia (Bier Block)

• IV administration of local anesthetic into an exsanguinated, tourniquet-occluded limb.
• Used for short distal upper limb procedures.
• Risk is systemic local anesthetic toxicity (LAST) if tourniquet deflates early.

---

3. Local Anesthesia & Monitored Anesthesia Care (MAC)

Local Anesthesia

• Ester-linked (metabolized by plasma cholinesterases): cocaine, procaine, tetracaine, benzocaine
• Amide-linked (metabolized by liver): lidocaine, bupivacaine, ropivacaine, levobupivacaine, mepivacaine

• Topical - surface application (mucous membranes, skin); EMLA cream, lidocaine gel
• Infiltration - direct injection into the wound/tissue
• Field block - ring of local anesthetic around the operative area
• Nerve block - injection adjacent to a specific nerve trunk

Monitored Anesthesia Care (MAC)

• Patient retains airway reflexes and spontaneous breathing.
• Sedation titrated with IV agents (propofol, midazolam, fentanyl).
• Frequently combined with local or regional anesthesia.
• Used for colonoscopy, cataract surgery, minor procedures.

---

Comparison at a Glance

---

Choice of Technique

1. Surgery type and site - abdominal, orthopedic, thoracic, etc.
2. Patient factors - ASA status, obesity, sleep apnea, coagulopathy (contra-indicates neuraxial blocks), patient preference
3. Duration and complexity of the procedure
4. Ambulatory vs inpatient - regional/local techniques favor earlier discharge

---

---

ANESTHESIA - Complete Notes (MBBS Level)

---

CHAPTER 1: INTRODUCTION TO ANESTHESIA

Three Main Classes

Goals of General Anesthesia (the "Triad")

1. Hypnosis/Unconsciousness - loss of awareness
2. Analgesia - pain suppression
3. Muscle relaxation - for surgical access and intubation

---

CHAPTER 2: PRE-ANESTHETIC ASSESSMENT

Goals of Pre-Anesthetic Evaluation

• Identify medical conditions that increase risk
• Optimize coexisting disease before surgery
• Discuss the anesthetic plan with the patient
• Obtain informed consent
• Review current medications for interactions

History Components

• Previous anesthetic history (difficult intubation? adverse reactions? family history of MH?)
• Current medications - anticoagulants, antihypertensives, steroids, insulin
• Allergies
• Last oral intake (NPO status)
• Systems review: cardiac, pulmonary, renal, hepatic, neurologic, endocrine

Physical Examination

• Airway assessment (see Chapter 7)
• Cardiovascular: BP, murmurs, signs of heart failure
• Pulmonary: wheeze, reduced air entry, SpO2
• Neurologic baseline

Laboratory Testing

• Not routine in healthy, asymptomatic patients for elective procedures
• Targeted based on history/exam findings
• Commonly ordered: CBC, electrolytes, coagulation (if anticoagulated), ECG (if cardiac history), CXR (if pulmonary disease), LFTs (if hepatic disease), pregnancy test (women of childbearing age)

---

ASA Physical Status Classification

---

NPO (Nil Per Os) - Fasting Guidelines (ASA 2017)

If NPO cannot be met (emergency), use Rapid Sequence Intubation (RSI) to reduce aspiration risk.

---

Perioperative Medication Management

• Beta-blockers: Continue perioperatively (do not stop)
• ACE inhibitors/ARBs: Reasonable to continue; can hold morning of surgery if hypotension is a concern
• Antiplatelet agents (e.g., aspirin): Continue if coronary stent <6 weeks; otherwise, often held 7-10 days pre-op
• Anticoagulants (warfarin, NOACs): Hold based on bleeding risk and indication
• Insulin: Reduced dose on day of surgery; blood glucose monitoring

---

CHAPTER 3: PHARMACOLOGY OF ANESTHESIA

A. INHALATIONAL AGENTS

Key Pharmacokinetic Parameters

• Measures how readily the agent dissolves in blood
• Low solubility = less drug needed in blood to reach equilibrium with alveolar gas = faster induction and emergence
• High solubility = more drug dissolves in blood = slower onset

• The alveolar concentration (vol%) at which 50% of patients do not move in response to surgical incision at 1 atm
• Inversely proportional to potency: higher MAC = less potent
• MAC is additive (e.g., 0.5 MAC sevoflurane + 0.5 MAC N2O = 1 MAC)
• Factors that decrease MAC: increasing age, hypothermia, opioids, alcohol, pregnancy, hypoxia, severe anemia
• Factors that increase MAC: hyperthermia, chronic alcohol use, infants/young children

Modern Volatile Agents

Properties of All Volatile Agents

• Vasodilators - decrease BP
• Dose-dependent myocardial depression
• Trigger malignant hyperthermia (MH) in susceptible patients
• Greenhouse gases - environmental concern
• React with desiccated CO2 absorbent to form carbon monoxide (desflurane > others)

Nitrous Oxide (N2O) - Special Points

• Analgesic (used in labor, dental procedures)
• Diffuses into air-filled body cavities - contraindicated in pneumothorax, bowel obstruction, middle ear surgery, air embolism
• Inactivates methionine synthase - megaloblastic anemia with prolonged exposure
• Second gas effect: accelerates uptake of co-administered volatile agent

---

B. INTRAVENOUS ANESTHETIC AGENTS

1. Propofol (2,6-diisopropylphenol)

• Mechanism: GABA-A receptor potentiation
• Uses: Induction (1.5-2.5 mg/kg IV), maintenance (TIVA), sedation for MAC/colonoscopy
• Pharmacokinetics: Highly lipid soluble; rapid distribution and clearance; recovery in minutes even after prolonged infusion (context-insensitive half-life for short infusions)
• Advantages: Antiemetic properties; rapid clear-headed recovery; anticonvulsant
• Disadvantages:
  • Causes apnea - only give where airway support available
  • Hypotension (decreases SVR and cardiac contractility)
  • Pain on injection (inject into large vein; use lidocaine pretreatment)
  • Myoclonus
  • Propofol Infusion Syndrome (PRIS): rare; high-dose prolonged infusion; features: cardiomyopathy, metabolic acidosis, rhabdomyolysis, hyperkalemia, hepatomegaly, lipemia

2. Ketamine

• Mechanism: NMDA receptor antagonist (dissociative anesthetic)
• Uses: Induction in hemodynamically unstable patients, procedural sedation, pediatric anesthesia, adjunct analgesia, burns dressing changes
• Advantages:
  • Preserves airway reflexes and spontaneous breathing
  • Bronchodilator (useful in asthma)
  • Increases HR, BP, CO (sympathomimetic) - good in shock/trauma
  • Profound analgesia
  • Can be given IM, IV
• Disadvantages:
  • Emergence phenomena (hallucinations, vivid dreams) - pretreat with midazolam
  • Increases intracranial pressure (ICP) and intraocular pressure
  • Increases secretions (pretreat with atropine/glycopyrrolate)
  • Contraindicated in: head injury, hypertensive crises, ischemic heart disease, psychosis, open-eye injury

3. Etomidate

• Mechanism: GABA-A potentiation
• Uses: Induction in cardiovascular-compromised patients (maintains hemodynamic stability)
• Advantages: Minimal cardiovascular depression; excellent hemodynamic stability
• Disadvantages:
  • Myoclonus on induction
  • Pain on injection
  • Adrenocortical suppression (inhibits 11-beta-hydroxylase) - a single dose suppresses cortisol for 6-8 hours; avoid prolonged use/infusion in ICU
  • Nausea, vomiting

4. Midazolam

• Mechanism: GABA-A receptor (benzodiazepine binding site) - increases Cl- conductance
• Uses: Premedication (anxiolytic), induction adjunct, sedation for MAC
• Effects: Hypnotic, anxiolytic, amnestic (anterograde amnesia), anticonvulsant, muscle relaxant
• Reversal: Flumazenil (competitive antagonist)
• Disadvantage: Respiratory depression; slow onset for induction

5. Thiopental (Thiopentone)

• Ultrashort-acting barbiturate; GABA-A potentiation
• Rapid induction (30 seconds); rapidly redistributed
• Causes dose-dependent CNS/respiratory/cardiovascular depression
• Decreases ICP, cerebral oxygen consumption - used in head injury (where available)
• Contraindicated in porphyria
• Largely replaced by propofol; still used in some countries for rapid sequence intubation (RSI) and neurosurgery

---

C. OPIOIDS IN ANESTHESIA

---

D. NEUROMUSCULAR BLOCKING AGENTS (NMBAs)

Types

• Mechanism: Binds and activates nicotinic ACh receptors at the NMJ → initial fasciculations → sustained depolarization block (Phase I block) preventing repolarization
• Metabolized by plasma cholinesterase (pseudocholinesterase)
• Onset: 45-60 seconds | Duration: ~10-15 minutes (short)
• Only depolarizing agent in clinical use
• Primary use: Rapid sequence intubation (RSI) and management of laryngospasm
• Dose: 1-1.5 mg/kg IV; 3-4 mg/kg IM (for laryngospasm when IV not available)

• Hyperkalemia (life-threatening) - contraindicated in burns (>24h after), paraplegia/quadriplegia, prolonged immobilization, crush injury, upper motor neuron disease, muscular dystrophy (upregulated extrajunctional receptors release massive K+)
• Malignant hyperthermia trigger - avoid if susceptible
• Bradycardia (especially in children, second dose - muscarinic effect) - give atropine prophylactically in children
• Raised IOP and ICP
• Raised intragastric pressure (mitigated by cricoid pressure)
• Muscle pains (myalgias) postoperatively from fasciculations
• Prolonged block in atypical pseudocholinesterase (Phase II block)

---

• Neostigmine (+ glycopyrrolate): inhibits acetylcholinesterase → increases ACh → competes with NMBA; ceiling effect at deep block; muscarinic side effects prevented by glycopyrrolate
• Sugammadex: Modified gamma-cyclodextrin; encapsulates and inactivates rocuronium and vecuronium; no muscarinic effects; can reverse even deep block (2 mg/kg moderate block, 4 mg/kg deep block, 16 mg/kg immediate reversal after RSI dose of rocuronium)

---

E. LOCAL ANESTHETICS

Properties

• Decreases systemic absorption → prolongs duration and intensity
• Reduces bleeding in field
• Do NOT use epinephrine-containing LA in: terminal arteries (fingers, toes, nose, ear, penis) - risk of ischemic necrosis

• CNS first (circumoral tingling, metallic taste, tinnitus, dizziness → seizures → coma)
• Then cardiac (bradycardia, arrhythmias, cardiovascular collapse) - bupivacaine especially cardiotoxic
• Treatment: Stop injection, ABC, seizure control (benzodiazepines), ACLS, 20% Intralipid emulsion (IV lipid rescue - sequesters lipid-soluble LA)

---

CHAPTER 4: AIRWAY MANAGEMENT

Airway Assessment (Pre-operatively)

1. Mallampati Score (oral opening assessment): Grade I-IV
   • I: See soft palate, uvula, pillars
   • II: See soft palate, uvula
   • III: See soft palate, base of uvula
   • IV: Cannot see soft palate
   • Grades III/IV predict difficult intubation
2. LEMON mnemonic:
   • L - Look externally (beard, obesity, short neck, small jaw)
   • E - Evaluate 3-3-2 rule (mouth opens ≥3 fingers, hyoid-to-chin ≥3 fingers, thyroid-to-floor of mouth ≥2 fingers)
   • M - Mallampati
   • O - Obstruction (tumor, abscess, foreign body)
   • N - Neck mobility (limited in C-spine disease, ankylosing spondylitis)
3. Thyromental distance <6.5 cm suggests difficult laryngoscopy
4. Mouth opening <3 cm (interincisal distance) - difficult intubation

Airway Devices

Steps of Endotracheal Intubation

1. Pre-oxygenation (breathe 100% O2 x3-5 min or 8 vital capacity breaths)
2. Preinduction medications (midazolam, fentanyl, anti-sialogogue if needed)
3. Induction (propofol/thiopental ± fentanyl)
4. Muscle relaxant (succinylcholine for RSI; rocuronium for routine or RSI)
5. Direct laryngoscopy (Macintosh blade - curved, placed in vallecula; Miller blade - straight, lifts epiglottis)
6. Visualize cords and pass ETT
7. Confirm placement: capnography (ETCO2), bilateral breath sounds, chest rise, no gastric bubbling
8. Secure and ventilate

ASA Difficult Airway Algorithm (Key Points)

1. Assess likelihood of difficulty in: mask ventilation, supraglottic airway, laryngoscopy, intubation, surgical airway access
2. Maintain supplemental oxygen throughout
3. Two strategies:
   • Awake intubation (if difficult predicted + unstable) - uses topical anesthesia + sedation; fiberoptic bronchoscope is gold standard
   • Intubation after induction (if can mask ventilate)
4. If cannot intubate after induction → try LMA → videolaryngoscope → fiberoptic
5. CICV (Cannot Intubate, Cannot Ventilate): Emergency cricothyrotomy / surgical airway

Rapid Sequence Intubation (RSI)

1. Pre-oxygenation
2. Cricoid pressure (Sellick's maneuver) - controversial, but widely used
3. IV induction (propofol or ketamine/etomidate)
4. Succinylcholine 1.5 mg/kg (or high-dose rocuronium 1.2 mg/kg)
5. No bag-mask ventilation between induction and intubation (except if SpO2 falling)
6. Intubate when cords visible

---

CHAPTER 5: CONDUCT OF GENERAL ANESTHESIA

Three Phases

Phase 1: Induction

• Transition from consciousness to unconsciousness
• IV induction most common (propofol ± fentanyl)
• Inhalational induction in children (sevoflurane) or patients without IV access
• Intubate or place LMA
• "Excitation phase" (stage II of Guedel) must be passed quickly

Phase 2: Maintenance

• Volatile agent (isoflurane, sevoflurane, desflurane) ± N2O
• Or TIVA (Total Intravenous Anesthesia): propofol infusion ± remifentanil infusion
• Supplemental opioids (fentanyl boluses or infusion)
• NMBAs as needed (train-of-four monitoring to guide dosing)
• Inhalational agents measured by expired concentration analyzer

Phase 3: Emergence

• Discontinue agents; allow elimination
• Reverse neuromuscular block (neostigmine + glycopyrrolate, or sugammadex)
• Suction airway, extubate when awake (follows commands, regular breathing, protective reflexes)
• Extubation criteria: SpO2 >95% on room air, respiratory rate adequate, able to lift head for 5 seconds
• Transfer to PACU (Post-Anesthesia Care Unit)

---

CHAPTER 6: INTRAOPERATIVE MONITORING

1. Oxygenation

• Pulse Oximetry (SpO2): Continuous; measures % saturation of Hb; standard of care; inaccurate with nail polish, dark skin, poor perfusion, CO poisoning
• FiO2 monitoring: Oxygen analyzer confirms inspired O2 concentration

2. Ventilation

• Capnography (ETCO2): Gold standard for ventilation monitoring and confirmation of intubation; normal ETCO2 35-45 mmHg; reduced with pulmonary embolism, cardiac arrest
• Airway pressure and tidal volume monitoring

3. Circulation

• ECG: Continuous - detects arrhythmias, ischemia (ST changes)
• Non-invasive BP: Automated oscillometric, every 3-5 minutes minimum
• Invasive arterial line: For major surgery, cardiac surgery, hemodynamic instability - continuous beat-to-beat monitoring; also for frequent ABG sampling
• Sites: Radial (most common), femoral, brachial

4. Temperature

• Required when significant temperature changes expected
• Sites: esophageal, rectal, nasopharyngeal, bladder

5. Neuromuscular Monitoring

• Train-of-Four (TOF): 4 supramaximal electrical stimuli to ulnar nerve; count of twitches guides NMBA dosing; TOF ratio ≥0.9 = adequate recovery before extubation

6. Depth of Anesthesia

• BIS (Bispectral Index): Processed EEG; 0-100 scale; 40-60 = surgical anesthesia; helps avoid awareness

---

CHAPTER 7: REGIONAL ANESTHESIA

A. Neuraxial Anesthesia

Spinal Anesthesia (Subarachnoid Block)

• Technique: LA injected directly into CSF in subarachnoid space
• Level: L3-L4 or L4-L5 (below conus medullaris = L1 in adults, L2-L3 in infants)
• Onset: Rapid (2-5 min) | Dense, predictable block
• Agents: Hyperbaric bupivacaine 0.5% most common; also tetracaine, lidocaine
• Baricity: Hyperbaric (heavy) = denser than CSF → sinks with gravity; isobaric = stays; hypobaric = rises
• Level of block determined by: dose/volume, baricity, patient position, patient height

1. Hypotension (most common) - sympathetic block → vasodilation; treat with IV fluids, vasopressors (ephedrine for hypotension with bradycardia; phenylephrine for isolated hypotension)
2. Post-Dural Puncture Headache (PDPH) - positional (worse sitting/standing, better lying); onset 24-48h; lasts days; treat: bed rest, hydration, caffeine, blood patch (gold standard)
3. Urinary retention - especially with opioid additives or if mobilization delayed
4. Bradycardia - from high sympathetic block; treat atropine
5. High/Total spinal - LA ascends to cervical/brainstem level → apnea, unconsciousness, hemodynamic collapse; treat: immediate airway, vasopressors
6. Neurological complications (rare): cauda equina syndrome (especially with hyperbaric lidocaine - "transient neurologic symptoms"), epidural hematoma, meningitis

• Absolute: Patient refusal, coagulopathy/anticoagulation, infection at site, raised ICP
• Relative: Systemic infection (bacteremia), pre-existing neurological disease, hypovolemic shock (relative), severe aortic stenosis

Epidural Anesthesia

• Technique: LA injected into epidural space (outside dura) via catheter or single shot
• Access: Lumbar (most common), thoracic (post-thoracotomy analgesia), caudal (pediatric)
• Onset: Slower than spinal (15-20 min); easily titratable via catheter
• Agents: Bupivacaine 0.25-0.5%, ropivacaine 0.1-0.375%, ± opioid (fentanyl, morphine)
• Uses: Labor analgesia, post-op analgesia (especially thoracic and major abdominal), lower limb surgery

Combined Spinal-Epidural (CSE)

• Best of both: rapid dense spinal block + epidural catheter for top-ups/extended analgesia
• Common for C-section and major joint surgery

---

B. Peripheral Nerve Blocks

• Exsanguinate limb → tourniquet → inject IV lidocaine into distal vein
• Works for short forearm procedures
• Risk: LAST if tourniquet deflates too early (must maintain for >20-25 min)

---

CHAPTER 8: LOCAL ANESTHETIC TECHNIQUES

Topical Anesthesia

• Applied directly to mucous membranes or skin
• EMLA cream (eutectic mixture of lidocaine 2.5% + prilocaine 2.5%): apply under occlusive dressing 45-90 min before IV cannulation in children; prilocaine risk - methemoglobinemia
• Lidocaine gel/spray: laryngoscopy, endoscopy, urethral catheterization
• Cocaine: nasal/ENT procedures (topical only; vasoconstriction bonus)

Infiltration Anesthesia

• Direct injection into tissue; most commonly used technique in ED and minor surgery
• Onset rapid; ring block (field block) around operative area for larger areas

---

CHAPTER 9: COMPLICATIONS OF ANESTHESIA

A. Malignant Hyperthermia (MH)

• Mutation in RYR1 gene (ryanodine receptor on sarcoplasmic reticulum) → uncontrolled Ca2+ release → sustained muscle hypermetabolism

• Muscle rigidity (masseter spasm often first sign)
• Hyperthermia (may rise 1°C every 5 min - late sign)
• Tachycardia + tachypnea (earliest signs)
• Hypercarbia (rising ETCO2 despite unchanged ventilation - often first sign)
• Metabolic acidosis
• Rhabdomyolysis + hyperkalemia + myoglobinuria

1. Stop all triggering agents immediately
2. Hyperventilate with 100% O2
3. Dantrolene 2.5 mg/kg IV rapidly → repeat until symptoms resolve (max ~10 mg/kg); mechanism: blocks ryanodine receptor Ca2+ release from SR
4. Cool the patient (ice packs, cold IV fluids)
5. Treat arrhythmias (avoid calcium channel blockers with dantrolene)
6. Correct acidosis and hyperkalemia
7. Monitor urine output (myoglobinuria) - hydrate, alkalinize urine

---

B. Pulmonary Aspiration

• Incidence: 1 in 2000-3000 cases
• Risk factors: full stomach, emergency surgery, obesity, pregnancy, opioids, DM, GERD, bowel obstruction
• Can occur during induction OR emergence
• Consequences: chemical pneumonitis (Mendelson syndrome) → aspiration pneumonia → ARDS
• Prevention: NPO guidelines, RSI, cricoid pressure, awake intubation

---

C. Postoperative Nausea and Vomiting (PONV)

1. Female sex
2. Non-smoker
3. History of PONV/motion sickness
4. Postoperative opioid use

---

D. Postoperative Cognitive Dysfunction (POCD) and Delirium

• More common in elderly patients
• Associated with deeper levels of anesthesia (BIS monitoring may help)
• Prolonged POCD can persist weeks-months

---

E. Awareness Under Anesthesia

• Patient regains consciousness during GA; may recall events
• Incidence: ~1-2 per 1000 GA cases
• Higher risk: cardiac surgery, C-section (reduced induction doses), RSI
• Prevention: BIS monitoring, adequate MAC monitoring, TIVA
• Management: Psychological support; formal PTSD counseling if needed

---

F. Latex Allergy

• Anaphylaxis risk during surgery
• High-risk: children with spina bifida, multiple surgeries, healthcare workers
• Manage: Latex-free environment, antihistamines + steroids premedication; epinephrine for anaphylaxis

---

CHAPTER 10: POSTANESTHETIC CARE

PACU Monitoring (Phase 1 Recovery)

• Continuous SpO2, ECG, BP, respiratory rate
• Pain assessment and management (IV opioids, NSAIDS, regional techniques)
• Aldrete score used for discharge from PACU (scores activity, respiration, circulation, consciousness, SpO2)

Common PACU Problems

Discharge Criteria (Ambulatory/Day Surgery)

• Vital signs stable
• Pain controlled on oral analgesics
• No uncontrolled nausea/vomiting
• Voided urine
• Responsible adult escort
• Written discharge instructions

---

CHAPTER 11: SPECIAL TOPICS

Obstetric Anesthesia

• Labor analgesia: Epidural (gold standard) - 0.1% bupivacaine + fentanyl; patient-controlled epidural analgesia (PCEA)
• Cesarean section:
  • Elective: Spinal (preferred) - hyperbaric bupivacaine 0.5% + fentanyl + morphine
  • Emergency: Category 1 (immediate threat to life) - GA with RSI; Category 2/3 - spinal or extending existing epidural
• Concerns: Aortocaval compression (left lateral tilt in late pregnancy), difficult airway (full stomach, edematous airway), aspiration risk
• Spinal hypotension in obstetrics: More severe; treat with left lateral tilt, IV fluids, phenylephrine (preferred over ephedrine for fetal acidosis risk)

Pediatric Anesthesia

• Anatomical differences: Larger head/tongue, anterior/cephalad larynx (epiglottis floppy and angled), shorter trachea (risk of mainstem intubation), narrow subglottic region (cricoid = narrowest point in children <8 years)
• Use uncuffed ETT in children <8 years (or cuffed with careful monitoring)
• ETT size (internal diameter) = (Age/4) + 4 for uncuffed; (Age/4) + 3.5 for cuffed
• Inhalational induction with sevoflurane common (no IV access)
• Succinylcholine caution: bradycardia - give atropine 0.02 mg/kg pre-treatment
• Higher MAC than adults; faster induction/emergence (smaller FRC, higher metabolic rate)
• Halothane hepatitis risk lower in children

Geriatric Anesthesia

• Decreased MAC (MAC decreases ~6% per decade after age 40)
• Decreased cardiac reserve; polypharmacy and drug interactions
• Higher risk PONV, delirium, POCD
• Prolonged emergence
• Careful hydration (less cardiac reserve)

Anesthesia in Cardiac Patients (RCRI - Revised Cardiac Risk Index)

1. High-risk surgery (intraperitoneal, intrathoracic, suprainguinal vascular)
2. Ischemic heart disease
3. Congestive heart failure
4. Cerebrovascular disease
5. Insulin-dependent diabetes
6. Creatinine >2.0 mg/dL

---

QUICK REVISION TABLE: Key Drug Doses

---