Anesthesia Induction, Airway & Monitoring for NEET PG 2026

Master anesthesia for NEET PG 2026 — ASA grading, Mallampati, induction agents, NMBs, inhalational agents, monitoring standards, and LAST management.

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

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

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.

Inhalational agents — MAC, kinetics, idiosyncrasies

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.

Malignant hyperthermia

Rare autosomal dominant (RYR1 mutation) reaction to all halogenated volatiles + succinylcholine triggering uncontrolled calcium release from sarcoplasmic reticulum.

• Earliest sign: rising EtCO2 (despite increased ventilation), unexplained tachycardia, masseter spasm.
• Late: hyperthermia, rhabdomyolysis, hyperkalemia, DIC.
• 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"

Reversal

• 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.

Intra-operative monitoring

ASA standards (2020 update)

Continuous evaluation of four parameters:

1. Oxygenation — pulse oximetry (mandatory) + inspired oxygen analyser.
2. Ventilation — capnography (EtCO2) — gold standard for ETT placement and ongoing ventilation; inspired/expired volumes; airway disconnection alarms.
3. Circulation — continuous ECG, HR, BP every 5 min minimum.
4. Temperature — continuous monitoring during cases >30 min or if temperature change is intended.

Capnography clinical pearls

• Sudden EtCO2 drop to zero — circuit disconnection, accidental extubation, complete airway obstruction.
• Gradual EtCO2 drop with low BP — pulmonary embolism, cardiac arrest, hypovolemia.
• Rising EtCO2 — hypoventilation, malignant hyperthermia (early sign), CO2 insufflation in laparoscopy.
• Bronchospasm pattern — sloping (shark-fin) capnogram.

Depth of anesthesia — BIS

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)

1. Stop injection. Call for help and lipid rescue kit.
2. Airway: 100% oxygen; avoid hyperventilation (worsens cardiotoxicity).
3. Seizures: benzodiazepine (midazolam, lorazepam) preferred; small-dose propofol acceptable.
4. 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.
5. Modified ACLS: epinephrine <1 mcg/kg (10-100 mcg in adults), avoid vasopressin, calcium channel blockers, beta-blockers, lidocaine.
6. Cardiopulmonary bypass / ECMO if refractory to lipid resuscitation.

High-yield NEET PG MCQ traps

1. Succinylcholine + burn — fatal hyperkalemia after 24 hr of injury; avoid.
2. Etomidate + sepsis — even single dose suppresses adrenal axis 6-8 hr; consider stress steroid coverage.
3. Ketamine + raised ICP — historical contraindication is now relaxed in trauma; sympathetic stimulation can preserve cerebral perfusion.
4. Halothane hepatitis — type II reaction (immune-mediated); now largely a historical concern.
5. Propofol infusion syndrome — pediatric ICU sedation >48 hr, >4 mg/kg/hr; metabolic acidosis, rhabdomyolysis.
6. Nitrous oxide + closed gas spaces — pneumothorax, bowel obstruction, middle ear, intraocular gas; expansion within minutes.
7. First-line vasopressor for spinal anesthesia hypotension — phenylephrine in healthy obstetric patients (preserves uterine perfusion); ephedrine if bradycardic.
8. Wide-complex tachycardia in LAST — lipid first, NOT amiodarone or lidocaine.
9. Pseudocholinesterase deficiency — prolonged paralysis after succinylcholine or mivacurium; supportive ventilation until recovery.
10. 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.

Written by: NEETPGAI Editorial Team Reviewed by: Pending SME Review Last reviewed: April 2026