Effect of Ketamine on Inflammatory and Immune Responses After Short-Duration Surgery in Obese Patients

In non-obese patients ketamine decreases inflammatory responses and prevents overexpression of immune responses. Its effect in obese patients is unknown. This prospective, blinded, randomized controlled trial was designed to determine the effect of ketamine on cytokines and immune cell responses after short-duration surgery in obese patients. Thirty-six patients received either ketamine 0.15 mg/kg IV prior to induction of general anesthesia, or an equal volume of normal saline. Cytokine concentrations and immune cell responses were determined pre-operatively and at 4, 24, and 48 h after operation. Interleukin (IL)-6 production was significantly greater in the control group (126.0 +/- 18.8 ng/ml, mean +/- SEM, n = 19) than in the ketamine group (57.9 +/- 8.4 ng/ml) at 4 h. At other time periods IL-6 and tumor necrosis factor alpha increased and IL-2, lymphocyte proliferation, and natural killer cell cytotoxity decreased compared to pre-operative values in the control group but not in the ketamine group. We conclude that effects of ketamine on inflammatory and immune responses after short-duration surgery in obese patients are similar to those previously reported in non-obese patients.