Which factor best explains why desflurane is often favored for rapid emergence?

Which factor best explains why desflurane is often favored for rapid emergence?

• A. High MAC
• B. Low blood/gas partition coefficient
• C. High oil/gas partition coefficient
• D. Low vapor pressure

Answer: (B)

Rapid emergence from inhaled anesthetics hinges on how readily the agent leaves the blood and is exhaled. This is quantified by the blood/gas partition coefficient—the lower it is, the less soluble the drug is in blood, so it equilibrates quickly between the alveoli and blood and, as a result, brain concentrations fall faster when ventilation resumes or inspired concentration is reduced. Desflurane has one of the lowest blood/gas partition coefficients among volatile anesthetics, meaning it is eliminated quickly and recovery occurs rapidly. Other factors like MAC reflect potency, not how fast you wake up; a higher MAC means you need more drug to achieve anesthesia, not faster emergence. The oil/gas partition coefficient represents tissue storage—higher values slow emergence due to more reservoir in fat and tissues, whereas desflurane’s low lipid solubility favors faster recovery. Vapor pressure affects controllability of delivery during anesthesia but doesn’t itself determine how quickly the drug is eliminated after the anesthetic is stopped.

Rapid emergence from inhaled anesthetics hinges on how readily the agent leaves the blood and is exhaled. This is quantified by the blood/gas partition coefficient—the lower it is, the less soluble the drug is in blood, so it equilibrates quickly between the alveoli and blood and, as a result, brain concentrations fall faster when ventilation resumes or inspired concentration is reduced. Desflurane has one of the lowest blood/gas partition coefficients among volatile anesthetics, meaning it is eliminated quickly and recovery occurs rapidly.

Other factors like MAC reflect potency, not how fast you wake up; a higher MAC means you need more drug to achieve anesthesia, not faster emergence. The oil/gas partition coefficient represents tissue storage—higher values slow emergence due to more reservoir in fat and tissues, whereas desflurane’s low lipid solubility favors faster recovery. Vapor pressure affects controllability of delivery during anesthesia but doesn’t itself determine how quickly the drug is eliminated after the anesthetic is stopped.