Pulmonary artery temperature was similar in the two groups before and after the induction of anesthesia (Fig 1), while it decreased to 25.6±3.2°C in group 1 and 34.3±2.8°C in group 2 (intergroup difference: p<0.001) 15 min after starting CPB and increased to 36.6±0.7°C and 36.1±0.7°C (p>0.05), respectively, at the end of CPB. After the end of surgery, pulmonary artery temperature continued to increase to 37.3±0.7°C in group 2 and was significantly higher than in group 1 (Fig 1).
Blood gas levels and arterial pH were within physiologic values in all patients without intergroup difference except arterial pH at the end of CPB (7.47 ± 0.06 in group 1, 7.41 ±0.05 in group 2; p<0.02). At the beginning of CPB, blood lactate level was 4.29 ±0.46 mmol/L in group 1 and 4.84 ±0.46 mmol/L in group 2 (p>0.05), and 3.8 ±0.39 and 4.09 ±0.45 mmol/L, respectively, at the termination of CPB (p>0.05).
Blood glucose and plasma hormone concentrations were similar in the two groups before and after induction of anesthesia. Before induction of anesthesia, the patients were slightly hyperglycemic (Fig 1). Blood glucose levels did not change after induction of anesthesia, even though they increased but not significantly in group 1 ( + 8 percent) and significantly in group 2 ( + 28 percent) 15 min after starting CPB.
Figure 1. Pulmonary artery temperature, blood glucose, plasma insulin and glucagon concentrations in group 1 (open circles, hypothermic CPB) and in group 2 (normothermic CPB). Values are mean±SEM. Key to symbols: asterisk, different from control; + different from group 1 (p<0.05). C, onset of cooling in group 1; A, onset of rewarming in group 1; D, onset of dextrose infusion in both groups. See text for interval times.