How is geriatric anesthetic dosing typically adjusted relative to healthy adults?

How is geriatric anesthetic dosing typically adjusted relative to healthy adults?

• A. Increased to about 150%
• B. Reduced to about 1/2 to 1/4 of the healthy dose
• C. Unchanged
• D. Increased to about 2x

Answer: (B)

In older adults, lower doses are needed because aging changes how drugs behave in the body and how the body responds to them. Hepatic blood flow and renal function decline, which slows metabolism and excretion of anesthetic drugs. Body composition shifts—fat increases and total body water decreases—alter how drugs distribute, often making effects more pronounced or longer-lasting. The nervous system also becomes more sensitive to sedatives and anesthetics, so the same amount of drug can produce stronger depressant effects. Taken together, these factors mean you must start with substantially smaller doses and adjust gradually. That’s why the typical approach is to use about half to a quarter of the healthy adult dose, then titrate to the desired effect while monitoring anesthesia depth and vital signs. The other options would either overshoot the effect or ignore the known age-related changes.

In older adults, lower doses are needed because aging changes how drugs behave in the body and how the body responds to them. Hepatic blood flow and renal function decline, which slows metabolism and excretion of anesthetic drugs. Body composition shifts—fat increases and total body water decreases—alter how drugs distribute, often making effects more pronounced or longer-lasting. The nervous system also becomes more sensitive to sedatives and anesthetics, so the same amount of drug can produce stronger depressant effects. Taken together, these factors mean you must start with substantially smaller doses and adjust gradually.

That’s why the typical approach is to use about half to a quarter of the healthy adult dose, then titrate to the desired effect while monitoring anesthesia depth and vital signs. The other options would either overshoot the effect or ignore the known age-related changes.