A rapid onset of anesthesia is achieved by using an inhalant anesthetic with low solubility.

• A. True
• B. False
• C. It depends on the species
• D. It depends on the administration method

Answer: (A)

The speed of induction with an inhaled anesthetic depends on how soluble the agent is in blood. An agent with low blood solubility doesn’t dissolve much in the blood, so it quickly moves from the lungs into the brain. This rapid transfer raises the brain’s anesthetic partial pressure fast, producing anesthesia promptly. If the agent dissolves more in blood (high solubility), it takes longer to reach the brain, delaying onset and slowing induction and recovery.

So, using an inhalant with low solubility yields a rapid onset. The effect isn’t dictated by species or administration method as the main factor; those can influence kinetics a bit, but the fundamental determinant here is the agent’s blood-gas solubility.