INCREASED OXYGEN-CONSUMPTION AFTER CARDIAC-SURGERY IS ASSOCIATED WITHTHE INFLAMMATORY RESPONSE TO ENDOTOXEMIA

Objective: The aim of this study was to determine whether the increase in post-operative oxygen consumption (Delta VO2) in cardiac surgery p atients is related to endotoxemia and subsequent cytokine release and whether Delta VO2 can be used as a parameter of post-perfusion syndrom e. Design: Prospective study. Setting: Operating room and intensive ca re unit of a university hospital. Patients: Twenty-one consecutive mal e patients undergoing elective coronary artery bypass surgery without major organ dysfunction and not receiving corticosteroids. Measurement s and results: Plasma levels of endotoxin, tumor necrosis factor (TNF) and interleukin-6 (IL-6) were measured before, during and for 18 h af ter cardiac surgery. Oxygen consumption, haemodynamics, the use of IV fluids and dopamine, body temperature and the time of extubation were also measured. Measurements from patients with high Delta VO2 (greater than or equal to median value of the entire group) were compared with measurements from patients with low Delta VO2 (<median). Patients wit h high Delta VO2 had higher levels of circulating endotoxin (P = 0.004 ), TNF (P = 0.04) and IL-6 (P = 0.009) received more IV fluids and dop amine while in the ICU, and were extubated later than patients with lo w Delta VO2. Several hours after Delta VO2 the patient's body temperat ure rose. Forward stepwise regression analysis showed that circulating endotoxin and TNF explained 50% of the variability of Delta VO2. Conc lusions: This study demonstrates that patients with high post operativ e oxygen consumption after elective cardiac surgery have higher circul ating levels of endotoxin, TNF and IL-6 and also have more symptoms of post-perfusion syndrome. Early detection of high VO2 might be used as a clinical signal to improve circulation in order to meet the high ox ygen demand of inflammation. In addition, continuous measurement of VO 2 provides us with a clinical parameter of inflammation in interventio nal studies aiming at a reduction of endotoxemia or circulating cytoki nes.