Arrange the following agents in order from FASTEST to SLOWEST induction of anaesthesia based on their blood:gas partition coefficients:
- A Nitrous oxide < desflurane < sevoflurane < isoflurane < halothane
- B Desflurane < nitrous oxide < sevoflurane < isoflurane < halothane ✓
- C Sevoflurane < desflurane < isoflurane < nitrous oxide < halothane
- D Desflurane < sevoflurane < nitrous oxide < halothane < isoflurane
Correct answer: B. Desflurane < nitrous oxide < sevoflurane < isoflurane < halothane
Explanation
Lower blood solubility means faster equilibration between alveoli and brain. Approximate blood:gas coefficients are desflurane 0.42, nitrous oxide 0.47, sevoflurane 0.65, isoflurane 1.4 and halothane 2.4. Desflurane edges out nitrous oxide despite similar values. The commonest error is placing sevoflurane ahead of nitrous oxide, since 0.65 is clearly higher than 0.47.
Reference: Miller's Anesthesia, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.