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The effects of two rewarming strategies on heat balance and metabolism after coronary artery bypass surgery with moderate hypothermia
Author(s) -
Hanhela R.,
Mustonen A.,
Korhonen I.,
Salomäki T.
Publication year - 1999
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1034/j.1399-6576.1999.431003.x
Subject(s) - medicine , hypothermia , cardiopulmonary bypass , anesthesia , coronary artery bypass surgery , artery , cardiac surgery , surgery
Background: Postoperative hypothermia is common in cardiac surgery with hypothermic cardiopulmonary bypass (CPB). This trial was designed to evaluate whether rewarming over the normal bladder temperature (over 37°C) at the end of hypothermic CPB combined with passive heating methods after CPB might result in a better heat balance, lower energy expenditure (EE) and decrease of disturbances in oxygen balance compared to only rewarming the patients to a bladder temperature of 35–37°C. Methods: A prospective, randomized controlled clinical study was performed in 38 patients scheduled for elective coronary artery bypass surgery. Twenty patients (group C) were rewarmed to a bladder temperature of 35–37°C at the end of hypothermic (28°C) CPB. Eighteen patients (group W) were rewarmed to a bladder temperature of 37–38.5°C. Results: At the end of CPB, the bladder temperature was 36.2±0.7°C (mean±SD) in group C and 37.9±0.5°C in group W. After half an hour’s stay in the ICU, the mean body temperature (MBT) was 35.1±0.6°C in group C and 36.6±0.7°C in group W. During the following five hours, MBT increased to 37.4±0.8°C in group C and to 38.0±0.6°C in the other group. The peak value of EE in the ICU was 1.73±0.44 (group C) vs 1.35±0.29 (W/kg) (group W) ( P =0.003). EE was significantly ( P =0.044 ) higher in group C than in the other group between 1.5 and 5.5 h in the ICU. The increased energy expenditure due to heat production was associated with an increase in O 2 consumption (V˙O 2 ) 61.6±30.4% vs 25.2±24.1%, (peak values) compared to the basal values of the two groups measured before anesthesia (between groups P <0.001). Between 1.5 and 5.5 h in the ICU, group C had significantly higher V˙O 2 ( P =0.026), CO 2 production ( P =0.017), venous pCO 2 ( P <0.001) and minute ventilation (p=0.014) than group W. Venous pH was lower ( P <0.001) in group C. The peak value of oxygen extraction was also higher ( P =0.045) in group C. On the other hand, the lowest value of venous oxygen saturation was higher ( P =0.04) in group W. Conclusion: With rewarming the patients at the end of CPB to a bladder temperature of over 37°C combined with passive heating methods after CPB, it was possible to decrease EE and V˙O 2 compared to the control group (rewarmed to bladder temperature of 35–37°C) after coronary artery bypass surgery with moderate hypothermia.