Which regional anesthesia technique is associated with the highest serum concentration of lidocaine?

Which regional anesthesia technique is associated with the highest serum concentration of lidocaine?

• A. Intercostal
• B. Caudal
• C. Epidural
• D. Brachial plexus

Answer: (A)

The main idea is that how much lidocaine ends up in the bloodstream depends on how quickly it’s absorbed from the injection site, which in turn follows the vascularity of that area. The intercostal space has a rich blood supply from the intercostal arteries and associated venous plexuses, and intercostal blocks are often done at multiple levels. That combination leads to rapid and substantial systemic absorption, producing the highest serum lidocaine concentrations among these techniques. In contrast, injections in the sacral caudal area enter a less vascular space and absorb more slowly; epidural injections, while in a vascular region, generally produce slower peak levels than intercostal blocks; and brachial plexus blocks occur in a relatively less vascular milieu, leading to lower peak serum concentrations for similar doses. This is why intercostal blocks carry the greatest risk of systemic lidocaine toxicity and require careful dosing and monitoring.

The main idea is that how much lidocaine ends up in the bloodstream depends on how quickly it’s absorbed from the injection site, which in turn follows the vascularity of that area. The intercostal space has a rich blood supply from the intercostal arteries and associated venous plexuses, and intercostal blocks are often done at multiple levels. That combination leads to rapid and substantial systemic absorption, producing the highest serum lidocaine concentrations among these techniques. In contrast, injections in the sacral caudal area enter a less vascular space and absorb more slowly; epidural injections, while in a vascular region, generally produce slower peak levels than intercostal blocks; and brachial plexus blocks occur in a relatively less vascular milieu, leading to lower peak serum concentrations for similar doses. This is why intercostal blocks carry the greatest risk of systemic lidocaine toxicity and require careful dosing and monitoring.