Why is the use of a tourniquet discouraged in some local anesthetic applications?

The use of a tourniquet is discouraged in local anesthetic applications primarily because it can lead to ischemia and increased risk of toxicity. When a tourniquet is applied, it restricts blood flow to the area being treated, which can result in ischemia — a condition characterized by insufficient blood supply. This lack of blood flow can not only cause tissue damage but also affects how the body metabolizes and clears the anesthetic agent.

In the context of local anesthesia, if the anesthetic is administered while a tourniquet is in place, the drug may accumulate in the tissue due to the restricted circulation. Once the tourniquet is released, there is a sudden influx of blood to the area, potentially leading to a rapid release of the anesthetic into the systemic circulation. This can increase the risk of local anesthetic systemic toxicity (LAST), which may manifest as symptoms ranging from central nervous system (CNS) disturbance to cardiovascular issues.

Therefore, utilizing a tourniquet requires careful consideration and is often avoided to minimize these risks, ensuring that procedures remain safe and effective for patients.