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.