Prevention of body temperature reduction (afterdrop) following hypothermic perfusion

Abstract

This study investigated the possibility of preventing the postoperative reduction in body temperature (afterdrop) which followed a period of hypothermic cardiopulmonary bypass. In addition to warming all the infused fluids and inspired gases, the patients also had active warming by way of a system of hot water mattresses and limb jackets. In the eight male patients randomly allocated to the active treatment there were no significant changes on the central (aural) temperature in the five hours following the end of perfusion. The eight male control patients showed significant ( p<0.05) falls in central temperature from 36.5 (0.3)°C at the end of bypass to 35.3 (0.2)°C and 35.0 (0.2)°C at one and two hours postperfusion. In addition, the mean skin temperatures were always significantly higher in the active warming group during the study period. This maintenance of a stable body temperature was reflected in the carbon dioxide production, which showed no significant changes in the actively warmed group. In the control group the carbon dioxide production was reduced from the preoperative value of 189 (26)ml/min (mean (SEM)) to 155 (9.2)ml/min ( p<0.05) at two hours postperfusion. These data show that afterdrop following perfusion can be prevented by an aggressive rewarming policy and suggest that this may have beneficial effects in producing a metabolically and physiologically more stable patient.