What is the risk of injecting local anesthetic into a blood vessel?

Injecting local anesthetic into a blood vessel poses the significant risk of systemic toxicity, which can lead to life-threatening complications. When local anesthetics enter the bloodstream, they can quickly spread throughout the body and affect the central nervous system as well as the cardiovascular system. This can result in symptoms such as seizures, cardiac arrhythmias, hypotension, and even respiratory arrest.

Because the absorption of anesthetic agents into circulation can vary greatly depending on the specific drug used and the site of injection, any unintentional intravascular injection could exacerbate this risk. The immediate effects can occur rapidly after injection, making it vital to employ techniques to avoid intravascular placement, such as aspirating the syringe before injecting.

In contrast, the other options do not pose the same level of immediate risk. Infection at the injection site is a potential concern following any injection but does not typically have the same instant or severe consequences as systemic toxicity. An immediate allergic reaction, while possible, is much rarer and not directly tied to intravascular injection. Prolonged numbness could occur from various factors, including nerve irritation or damage, but again, it is not an immediate life-threatening risk associated with injecting into a blood vessel. Therefore, the systemic