Monitoring — ASA standards: oxygenation, ventilation, circulation, temperature; capnography (EtCO2) is gold standard for ETT placement.
LAST — lipid emulsion 20% bolus + infusion is the antidote.
Anesthesia questions on NEET PG hit pharmacology, physiology, and emergency-medicine reasoning all at once. Examiners ask about drug-specific cardiovascular profiles, the airway-assessment scoring systems that decide intubation strategy, the depth-of-anesthesia monitors that have moved from optional to mandatory, and the rare-but-lethal emergencies (LAST, malignant hyperthermia, anaphylaxis) that test ACLS-meets-pharmacology reasoning.
This NEETPGAI deep dive covers the ASA grading and airway examination, the pharmacology of induction and inhalational agents, neuromuscular blockade and reversal, intra-operative monitoring, and local anesthetic systemic toxicity. Pair this with the shock and sepsis management guide and the Anesthesia hub.
Pre-operative evaluation
ASA physical status classification
Grade
Description
Typical patient
ASA I
Healthy
Fit non-smoker, no disease
ASA II
Mild systemic disease
Controlled HTN/DM, smoker, social alcohol, BMI 30-40
Moribund, not expected to survive 24 hr without surgery
Ruptured AAA, massive trauma, intracranial bleed with mass effect
ASA VI
Declared brain-dead, organ donor
—
Add E for emergency status (e.g., ASA IIIE).
Airway assessment — multi-component
No single test is sufficient. Examiners expect you to know the panel:
Mallampati class (I-IV) — visualisation of oropharynx with mouth open, tongue protruded.
Thyromental distance <6.5 cm — predicts difficult laryngoscopy.
Sternomental distance <12.5 cm — difficulty.
Mouth opening (interincisor distance) <3 cm or 2 finger-breadths — difficulty.
Neck extension — atlanto-occipital movement <35° → difficult intubation.
Cormack-Lehane I-IV — direct laryngoscopy view (only assessable intra-operatively).
Wilson score, LEMON, MOANS — composite scores combining several factors.
Predictors of difficult bag-mask ventilation: MOANS — Mask seal (beard), Obesity, Age >55, No teeth, Snoring/stiff lungs.
NPO (fasting) guidelines
Intake
Minimum fasting time
Clear fluids (water, black tea/coffee, clear juice)
2 hours
Breast milk
4 hours
Infant formula / non-human milk
6 hours
Light meal (toast + clear liquids)
6 hours
Heavy meal (fried, fatty, meat)
8 hours
Modern guidelines emphasise NOT prolonging fasting unnecessarily. Aspiration risk is highest in emergency surgery, GERD, pregnancy, opioids, bowel obstruction, and increased intra-abdominal pressure.
Induction agents — the IV pharmacology grid
Agent
Onset
Duration
Hemodynamics
Key effects
Contraindications
Propofol
30-40 sec
5-10 min
Hypotension (vasodilation + cardiac depression)
Anti-emetic, anti-pruritic, anti-convulsant; pain on injection
Raised ICP (controversial), severe HTN, psychiatric history, intraocular surgery
Etomidate
30 sec
5-10 min
Hemodynamically stable
Myoclonus, post-op nausea, adrenal suppression
Sepsis (single dose still inhibits 11-β-hydroxylase for 6-8 hr); avoid infusion
Midazolam
1-3 min
30-60 min
Mild hypotension
Anterograde amnesia, anxiolysis
Reversal: flumazenil (caution in seizure-prone)
Dexmedetomidine
Slow load 10 min
Variable
Bradycardia, biphasic BP
Sedation without respiratory depression; analgesic
Heart block; hypovolemia
Quick clinical pearls
Propofol — the workhorse for elective induction and TIVA. Pain on injection minimised by lidocaine pre-treatment or large-vein injection. Avoid prolonged high-dose infusion (propofol infusion syndrome — metabolic acidosis, rhabdomyolysis, cardiac failure).
Thiopentone — historically dominant; now largely replaced by propofol. Still favoured in some neurosurgical and obstetric practices.
Ketamine — induction of choice in shock, severe asthma, prehospital trauma, burn dressings. Dissociative state means eyes may remain open with nystagmus.
Etomidate — induction of choice for hemodynamic instability (cardiac surgery, trauma) but a single dose still suppresses adrenal cortex for 6-8 hr.
Minimum Alveolar Concentration (MAC) is the alveolar concentration at which 50% of patients do not move to surgical stimulus. Standard reference: MAC of nitrous oxide is 104, sevoflurane 2.0, isoflurane 1.15, desflurane 6.0, halothane 0.75 (in adults). MAC decreases with age, hypothermia, opioids, alpha-2 agonists, hypotension, pregnancy. MAC increases in infants 1-6 months, hyperthyroidism, chronic alcoholism.
Treatment: stop trigger, hyperventilate with 100% O2 on clean circuit, dantrolene 2.5 mg/kg IV bolus (repeat to 10 mg/kg total). Cool, treat hyperkalemia and acidosis, manage rhabdomyolysis.
Neuromuscular blocking agents
Depolarising — succinylcholine
The only depolarising NMB in clinical use. Mechanism: persistent depolarisation of nicotinic receptor at neuromuscular junction → muscle fasciculation followed by flaccid paralysis.
Onset: 30-60 sec; ideal for rapid sequence intubation.
Duration: 5-10 min (hydrolysed by pseudocholinesterase).
Dose: 1-1.5 mg/kg IV.
Side effects: fasciculation, post-op myalgia, hyperkalemia (~0.5 mEq/L rise normally), bradycardia (especially second dose, especially in children), increased intraocular/intragastric/ICP, masseter spasm, malignant hyperthermia trigger.
Contraindications: burns >24 hr, denervation injury >24 hr, prolonged immobilisation, crush injury, upper motor neuron lesion (e.g., stroke), neuromuscular disease (Duchenne MD), familial pseudocholinesterase deficiency, history of MH.
Non-depolarising — "-curium" and "-curonium"
Drug
Class
Onset
Duration
Notes
Rocuronium
Aminosteroid
1-2 min
30-60 min
RSI alternative to succinylcholine; reversible by sugammadex
Vecuronium
Aminosteroid
2-3 min
30-60 min
Hepatic metabolism; prolonged in liver disease
Pancuronium
Aminosteroid
3-5 min
60-120 min
Vagolytic — tachycardia/HTN; long-acting
Atracurium
Benzylisoquinolinium
2-3 min
30-45 min
Hofmann elimination; safe in renal/hepatic failure; histamine release
Sugammadex — gamma-cyclodextrin that encapsulates rocuronium and vecuronium; reverses even deep blockade. Doses: 2 mg/kg (TOF count 2), 4 mg/kg (deep block), 16 mg/kg (immediate reversal of RSI dose).
Neostigmine — acetylcholinesterase inhibitor + glycopyrrolate or atropine (to block muscarinic effects). Effective only when at least 4/4 TOF responses present.
The Bispectral Index (BIS) processes EEG into a 0-100 score. Surgical anesthesia 40-60. Used in TIVA and to detect awareness in high-risk patients. Has reduced (but not eliminated) intraoperative awareness incidents.
Neuromuscular monitoring
Train-of-Four (TOF) — four supramaximal stimuli at 2 Hz at the ulnar nerve. TOF ratio (4th twitch / 1st twitch) below 0.9 means residual paralysis, which is the strongest predictor of post-op pulmonary complications. Aim for TOF ratio >0.9 before extubation.
Local anesthetic systemic toxicity (LAST)
LAST occurs when local anesthetic enters systemic circulation in toxic concentration — accidental intravascular injection or excess dose.
Risk hierarchy (most to least toxic)
Bupivacaine > ropivacaine > lidocaine. Bupivacaine has the worst cardiovascular toxicity profile (R-enantiomer binds tightly to cardiac sodium channels). Levobupivacaine and ropivacaine are safer alternatives.
Symptoms
CNS first (lower threshold): perioral numbness, tinnitus, lightheadedness, slurred speech, then seizures, then CNS depression and coma.
Cardiovascular (higher threshold): hypertension and tachycardia (early), then bradycardia, hypotension, conduction blocks, ventricular arrhythmias, cardiac arrest. Bupivacaine arrests are notoriously refractory to standard ACLS.
Maximum safe doses (with epinephrine)
Lidocaine: 5 mg/kg (7 mg/kg with adrenaline)
Bupivacaine: 2.5 mg/kg (3 mg/kg with adrenaline)
Ropivacaine: 3 mg/kg (3.5 mg/kg with adrenaline)
LAST management algorithm (ASRA 2020)
Stop injection. Call for help and lipid rescue kit.
Lipid emulsion 20%: 1.5 mL/kg bolus over 1 min, then 0.25 mL/kg/min infusion. Repeat bolus up to 3 times for cardiovascular collapse. Continue infusion for 10 min after stability.
Modified ACLS: epinephrine <1 mcg/kg (10-100 mcg in adults), avoid vasopressin, calcium channel blockers, beta-blockers, lidocaine.
Cardiopulmonary bypass / ECMO if refractory to lipid resuscitation.
High-yield NEET PG MCQ traps
Succinylcholine + burn — fatal hyperkalemia after 24 hr of injury; avoid.
Etomidate + sepsis — even single dose suppresses adrenal axis 6-8 hr; consider stress steroid coverage.
Ketamine + raised ICP — historical contraindication is now relaxed in trauma; sympathetic stimulation can preserve cerebral perfusion.
Halothane hepatitis — type II reaction (immune-mediated); now largely a historical concern.
Nitrous oxide + closed gas spaces — pneumothorax, bowel obstruction, middle ear, intraocular gas; expansion within minutes.
First-line vasopressor for spinal anesthesia hypotension — phenylephrine in healthy obstetric patients (preserves uterine perfusion); ephedrine if bradycardic.
Wide-complex tachycardia in LAST — lipid first, NOT amiodarone or lidocaine.
Pseudocholinesterase deficiency — prolonged paralysis after succinylcholine or mivacurium; supportive ventilation until recovery.
Awareness during anesthesia — risk factors include cardiac surgery, trauma, obstetric GA, total IV anesthesia without BIS monitoring.
Recent updates
Sugammadex — now standard alternative to neostigmine in many high-volume centres in India; allows rapid reversal of profound NMB.
High-flow nasal oxygen (HFNO / THRIVE) — extends safe apnoea time to 30+ minutes; useful in shared airway surgery, ICU intubation, predicted difficult intubations.
Video laryngoscopy — first-line in many DAS algorithms over direct laryngoscopy.
ERAS (Enhanced Recovery After Surgery) protocols — multimodal opioid-sparing analgesia, early enteral feeding, avoidance of routine NG tubes and drains.
Indian context: Indian Society of Anesthesiologists (ISA) guidelines align with ASA standards; rural and district-hospital settings often rely on ketamine and spinal anesthesia for safety and resource reasons. ASA monitoring standards are mandated in NABH-accredited hospitals.
Frequently asked questions
What are the ASA physical status classifications?
ASA I — healthy patient. ASA II — mild systemic disease (controlled hypertension, mild diabetes). ASA III — severe systemic disease, not incapacitating (poorly controlled diabetes, prior MI, COPD). ASA IV — severe disease that is constant threat to life (recent MI, advanced heart failure). ASA V — moribund, not expected to survive 24 hr without surgery. ASA VI — declared brain-dead organ donor. Suffix E for emergency.
What is the Mallampati classification?
Visualisation of oropharyngeal structures with patient seated, mouth open, tongue protruded. Class I — soft palate, fauces, uvula, pillars visible. Class II — soft palate, fauces, uvula visible. Class III — soft palate, base of uvula visible. Class IV — soft palate not visible at all. Class III/IV predicts difficult intubation but is one component of multi-factor airway assessment.
What are the NPO guidelines for elective surgery?
Clear fluids — 2 hours. Breast milk — 4 hours. Infant formula — 6 hours. Light meal (toast and clear fluids) — 6 hours. Heavy meal (fatty, fried, meat) — 8 hours. Modern guidelines emphasise minimising fasting beyond these limits to avoid dehydration. Aspiration risk is increased by emergency surgery, GERD, pregnancy, opioids, and bowel obstruction.
How do you manage local anesthetic systemic toxicity (LAST)?
Stop the injection, call for help, secure airway with 100% oxygen, avoid hyperventilation. Treat seizures with benzodiazepines. Lipid emulsion 20% — 1.5 mL/kg bolus then infusion at 0.25 mL/kg/min, repeat boluses for cardiovascular collapse. Avoid vasopressin, calcium channel blockers, beta-blockers, and propofol. Use small epinephrine doses (10-100 mcg). ACLS modified for LAST.
Which neuromuscular blocker is contraindicated in burn or denervation injury?
Succinylcholine — depolarising NMB. After 24-72 hours of burn, denervation, prolonged immobilisation, crush injury, or upper motor neuron lesion, extrajunctional acetylcholine receptors proliferate and cause massive potassium release on succinylcholine administration, leading to fatal hyperkalemic cardiac arrest. Use rocuronium with sugammadex reversal as alternative.
This content is for educational purposes for NEET PG exam preparation. It is not a substitute for professional medical advice, diagnosis, or treatment. Clinical information has been reviewed by qualified medical professionals.
Written by: NEETPGAI Editorial Team
Reviewed by: Pending SME Review
Last reviewed: April 2026
