How does the risk of local anesthetic systemic toxicity (LAST) differ between pediatric and elderly patients, and which dosing principle helps minimize risk?

How does the risk of local anesthetic systemic toxicity (LAST) differ between pediatric and elderly patients, and which dosing principle helps minimize risk?

• A. Elderly have decreased clearance and increased sensitivity
• B. Neonates have fully mature metabolism
• C. Ultrasound guidance increases risk
• D. Large bolus dosing reduces risk

Answer: (A)

Aging changes how local anesthetics behave in the body. In elderly patients, liver clearance and overall metabolism tend to decline, and the nervous system and myocardium become more sensitive to local anesthetics. This combination raises the risk of local anesthetic systemic toxicity (LAST) because drugs stay in the body longer and their toxic effects are more easily triggered. To minimize this risk, dosing must be more conservative in older adults: use the lowest effective dose, apply age- and weight-adjusted maximums, and give doses in small, incremental aliquots with careful monitoring for signs of LAST. Techniques like ultrasound guidance can help avoid intravascular injections, but the key is adjusting the dose itself and observing closely after administration. The other statements aren’t accurate: neonates do not have fully mature metabolism, ultrasound guidance does not increase risk (it reduces it by improving accuracy), and large bolus dosing increases—not reduces—the risk of LAST.

Aging changes how local anesthetics behave in the body. In elderly patients, liver clearance and overall metabolism tend to decline, and the nervous system and myocardium become more sensitive to local anesthetics. This combination raises the risk of local anesthetic systemic toxicity (LAST) because drugs stay in the body longer and their toxic effects are more easily triggered.

To minimize this risk, dosing must be more conservative in older adults: use the lowest effective dose, apply age- and weight-adjusted maximums, and give doses in small, incremental aliquots with careful monitoring for signs of LAST. Techniques like ultrasound guidance can help avoid intravascular injections, but the key is adjusting the dose itself and observing closely after administration.

The other statements aren’t accurate: neonates do not have fully mature metabolism, ultrasound guidance does not increase risk (it reduces it by improving accuracy), and large bolus dosing increases—not reduces—the risk of LAST.