What is the most significant risk factor associated with larger doses of local anesthetics?

The most significant risk factor associated with larger doses of local anesthetics is the increased chance of systemic toxicity. As the dose of a local anesthetic increases, so does the potential for the drug to enter systemic circulation, which can lead to adverse effects on the central nervous system (CNS) and cardiovascular system.

For instance, if a local anesthetic reaches high plasma concentrations, it can cause symptoms ranging from light-headedness and tinnitus to more severe manifestations like seizures, respiratory depression, and cardiac arrest. This risk is particularly crucial in settings where multiple injections are required or in patients with compromised metabolic clearance, as these scenarios can elevate systemic absorption levels.

While reduced effectiveness, delayed onset of action, and increased pain during administration can occur with varying doses or techniques, they do not pose the immediate and life-threatening risks associated with systemic toxicity. Understanding this inherent risk is vital for safe practice in anesthesiology, guiding practitioners in their choice of dosages to minimize harmful outcomes.