Halothane metabolism in acyanotic and cyanotic patients undergoing open heart surgery

The metabolism of halothane was examined in patients with acyanotic and cyanotic congenital heart disease undergoing open heart surgery. Statistically significant (P < 0.05) presurgical differences between acyanotic and cyanotic groups included pH (7.46 ± 0.02 vs 7.36 ± 0.02), PaO₂ (277 ± 58 vs 51 ± 3 torr), O₂ saturation (97 ± 1 vs 74 ± 4%), and hematocrit (45 ± 3 vs 58 ± 2%). Serum fluoride levels were significantly greater in cyanotic than in acyanotic groups 2-4 hours after initial exposure to halothane. Both groups had significant intragroup increases in serum levels of fluoride, bromide, and trifluoroacetic acid. Significant increases in serum levels of lactate dehydrogenase, creatinine phosphokinase, and glutamic oxaloacetate transaminase were observed in both groups, whereas, the cyanotic patients had additional significant increases in blood urea nitrogen and direct bilirubin. The cyanotic group also had higher total and direct serum bilirubin levels than the acyanotic group. Therefore, patients with cyanotic congenital heart disease had greater reductive metabolism of halothane than acyanotics. However, cyanotic and acyanotic patients had essentially similar postoperative derangements in hepatic and renal function.