Which inhalant anesthetic is characterized by very rapid induction and recovery times and is commonly used in high risk patients; about 3% of the drug is metabolized by the liver?

• A. Sevoflurane
• B. Epinephrine
• C. Fentanyl
• D. Xylazine

Answer: (A)

Rapid induction and recovery with inhalant anesthetics come from how quickly the agent moves between the blood and the brain, which depends mainly on its blood–gas solubility. An agent with low blood–gas solubility reaches effective brain concentrations rapidly and is cleared quickly by the lungs, allowing swift recovery once anesthesia is stopped.

Sevoflurane has a very favorable profile: it has low blood–gas solubility, so it induces anesthesia quickly andEmerges rapidly as you change the anesthetic concentration. Importantly, only a small portion is metabolized by the liver—about 3%—so it imposes a relatively light hepatic load, which is particularly advantageous in high-risk patients who may have hepatic concerns. This combination—rapid onset and offset plus limited hepatic metabolism—makes it a preferred inhalant in vulnerable patients.

The other choices are not inhaled volatile anesthetics. They are an analgesic or sedative/vasopressor type agent and do not provide the same inhalant profile for rapid induction and recovery.