Forced-air warming decreases vasodilator requirement after coronary arterybypass surgery

Post-operative hypothermia is common and associated with adverse hemodynami c consequences, including adrenergically mediated systemic vasoconstriction and hypertension. Hypothermia is also a known predictor of dysrhythmias an d myocardial ischemia in high-risk patients. We describe a prospective, ran domized trial designed to test the hypothesis that forced-air warming (FAW) provides improved hemodynamic variables after coronary artery bypass graft . After institutional review board approval and written informed consent, 1 49 patients undergoing coronary artery bypass graft were randomized to rece ive postoperative warming with either FAW (n = 81) or a circulating water m attress (n = 68). Core temperature was measured at the tympanic membrane. A weighted mean skin temperature was calculated. Heart rate, mean arterial b lood pressure, central venous pressure, cardiac output, and systemic vascul ar resistance were monitored for 22 h postoperatively. Mean arterial blood pressure was maintained by protocol between 70 and 80 mm Hg by titration of nitroglycerin and sodium nitroprusside. The two groups had similar demogra phic characteristics. Tympanic and mean skin temperatures were similar betw een groups on intensive care unit admission. During postoperative rewarming , tympanic temperature was similar between groups, but mean skin temperatur e was significantly greater in the FAW group (P < 0.05). Heart rate, mean a rterial pressure, central venous pressure, cardiac output, and systemic vas cular resistance were similar for the two groups. The percent of patients r equiring nitroprusside to achieve the hemodynamic goals was less (P < 0.05) in the FAW group. In conclusion, aggressive cutaneous warming with FAW res ults in a higher mean skin temperature and a decreased requirement for vaso dilator therapy in hypothermic patients after cardiac surgery. This most li kely reflection attenuation of the adrenergic response or opening of cutane ous vascular beds as a result of surface warming. Implications: Forced-air warming after cardiac surgery decreases the requirement for vasodilator dru gs and may be beneficial in maintaining hemodynamic variables within predef ined limits.