Histamine release in anesthesia and surgery.

Histamine release can occur in response to anaphylactic or chemically mediated anaphylactoid reactions during general anesthesia. Narcotics and muscle relaxants have been demonstrated both in vitro and in vivo to cause significant histamine release. This histamine release appears to be directly related to changes in the cardiovascular system that are often seen during anesthesia. The use of combined H1 and H2 antagonists to attenuate the effects of anaphylactoid reactions in humans has been shown in several controlled trials. In addition, recent experience with chymopapain administration suggests that the use of H1 and H2 antagonists may be useful in the prophylaxis of immunologically mediated reactions.