Inhalational induction is planned for a cooperative 5-year-old child who refuses cannulation. Which property makes sevoflurane the agent of choice for this technique?

• A Its pungent odour stimulates respiration and speeds alveolar wash-in
• B It is non-pungent with a pleasant odour and has low blood solubility allowing rapid, tolerated induction ✓
• C It has the lowest vapour pressure of all volatiles, permitting face-mask delivery without a vaporiser
• D It causes maximal bronchoconstriction, which protects against aspiration during induction

Explanation

Sevoflurane combines a low blood:gas partition coefficient of about 0.65 with a sweet, non-irritating odour, allowing children to tolerate incremental face-mask administration and achieving loss of consciousness quickly. Isoflurane is rejected for induction precisely because its pungency provokes coughing and breath holding. Its vapour pressure of about 157 mmHg still requires a conventional vaporiser, and volatile agents cause bronchodilation rather than constriction.

Reference: Morgan and Mikhail's Clinical Anesthesiology, 7th ed.

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