Impairment of leukocyte myeloperoxidase bactericidal mechanisms with ketamine (Ketalar).

The ability of general anesthetics to depress immune function may lead to increased risk of infection in surgical patients. Recently, halothane, an inhalational anesthetic, was shown to inhibit neutrophil bactericidal mechanisms, the center of which is the reaction of myeloperoxidase with H2O2 and Cl. This study demonstrates the ability of ketamine, an injectable anesthetic, to interfere with the cytotoxic neutrophil myeloperoxidase-H2O2-Cl- reaction, as tested using a luminol-enhanced chemiluminescence assay. Ketamine, due to its phenolic structure, may scavenge the cytotoxic free radical intermediates of this reaction, as shown previously for non-steroidal anti-inflammatory drugs. This paper, then, identifies a potential mechanism whereby ketamine anesthesia could suppress neutrophil defense mechanisms, thus rendering the surgical patient more susceptible to infection.