RESUMO
BACKGROUND: Small animal cardiopulmonary bypass (CPB) model would be a valuable tool for investigating pathophysiological and therapeutic strategies on bypass. The main advantages of a small animal model include the reduced cost and time, and the fact that it does not require a full scale operating environment. However the rat CPB models have a number of technical limitations. Effective maintenance and control of core temperature by a heat exchanger is among them. The purpose of this study is to comfirm the effect of rectal temperature maintenance using a heat exchanger of cardioplegia system in cardiopulmonary bypass model for rats. MATERIAL AND METHOD: The miniature circuit consisted of a reservoir, heat exchanger, membrane oxygenator, roller pump, and static priming volume was 40 cc. Ten male Sprague-Dawley rats (mean weight 530 gram) were divided into two groups, and heat exchanger (HE) group was subjected to CPB with HE from a cardioplegia system, and control group was subjected to CPB with warm water circulating around the reservoir. Partial CPB was conducted at a flow rate of 40 mg/kg/min for 20 min after venous cannulation (via the internal juglar vein) and arterial cannulation (via the femoral artery). Rectal temperature were measured after anesthetic induction, after cannulation, 5, 10, 15, 20 min after CPB. Arterial blood gas with hematocrit was also analysed, 5 and 15 min after CPB. RESULT: Rectal temperature change differed between the two groups (p<0.01). The temperatures of HE group were well maintained during CPB, whereas control group was under progressive hypothermia. Rectal temperature 20 min after CPB was 36.16+/-0.32 degrees C in the HE group and 34.22+/-0.36 degrees C in the control group. CONCLUSION: We comfirmed the effect of rectal temperature maintenance using a heat exchanger of cardioplegia system in cardiopulmonary bypass model for rats. This model would be a valuable tool for further use in hypothermic CPB experiment in rats.