Effectiveness of forced air warming after pediatric cardiac surgery employing hypothermic circulatory arrest without cardiopulmonary bypass.

STUDY OBJECTIVE: To evaluate the effectiveness of forced-air warming compared to radiant warming in pediatric cardiac surgical patients recovering from moderate hypothermia after perfusionless deep hypothermic circulatory arrest. DESIGN: Prospective unblinded study. SETIING: Teaching hospitals. PATIENTS: 24 pediatric cardiac surgical patients. INTERVENTION: Noncyanotic patients undergoing repair of atrial or ventricular septal defects were cooled by topical application of ice and rewarmed initially in the operating room by warm saline lavage of the pleural cavities. On arrival at the intensive care unit (ICU), patients were warmed by forced air (n = 13) or radiant heat (n = 11). The time, heart rate, and blood pressure at each 0.5 degrees C increase in rectal temperature were measured until normothermia (36.5 degrees C) to determine the instantaneous rewarming rate. MEASUREMENTS AND MAIN RESULTS: Baseline characteristics were not different in the two groups. The mean (+/- SD) age was 5.6 +/- 3.4 years, weight was 20 +/- 8 kg, esophageal temperature for circulatory arrest was 25.7 +/- 1.3 degrees C, and duration of circulatory arrest was 25 +/- 11 minutes. The mean core temperature on arrival at the ICU was 29.9 +/- 1.3 degrees C and ranged from 26.1 to 31.5 degrees C. The mean rewarming rate for each 0.5 degrees C was greater (p < 0.05) for forced-air (2.43 +/- 1.14 degrees C/hr) than radiant heat (2.16 +/- 1.02 degrees C/hr). At core temperatures <33 degrees C, the rewarming rate for forced-air was 2.04 +/- 0.84 degrees C/hr and radiant heat was 1.68 +/- 0.84 degrees C/hr (p < 0.05). At core temperatures > or = 33 degrees C, the rewarming rate for forced air was 2.76 +/- 1.20 degrees C/hr and radiant heat was 2.46 +/- 1.08 degrees C/min (p = 0.07). Significant determinants of the rewarming rate in a multivariate regression model were age (p < 0.001), temperature (p < 0.05), time after arrival to the intensive care unit (p < 0.05), pulse pressure (p < 0. 05) and warming device (p < 0.001). The duration of ventilatory support and ICU length of stay was not different in the two groups. CONCLUSIONS: Both forced-air and radiant heat were effective for rewarming moderately hypothermic pediatric patients. When core temperature was less than 33 degrees C, the instantaneous rewarming rate by forced air was 21% faster than by radiant heat.

Deep hypothermia without extracorporeal circulation in surgery of congenital cardiac defects.

Operations on the open heart under perfusionless deep hypothermia were performed in 3,141 patients with congenital cardiac defects. The patients ages ranged from 3 months to 44 years. The body was cooled to 26-24 degrees C by covering with crushed ice. Cooling was performed under conditions of not deep ether anesthesia with the use of minimum doses of narcotic analgetics (morphine 0.5 mg/kg). Lactacidemia was registered during hypothermia. In contrast to lactate, the content of fatty acids and 11-hydroxycorticosteroids during all the stages of hypothermia did not change significantly. The time of circulatory arrest ranged from 10-89 min. It took 2-7 min to restore cardiac activity. Of 3,141 patients operated on, 265 died (8.44%). The mortality pattern demonstrated that the major cause of death was cardiac insufficiency (5.9%). Neurological sequelae were observed in 110 patients (3.5%). Based on the results of tests with Luria's neuropsychological method, neurological disturbances were registered in 15.4% of patients. The frequencies of neuropsychological complications were not related to the time of circulatory arrest. Unstable hemodynamics after operation was the most contributory factor to the development of neurological complications. Perfusionless deep hypothermia is an efficient method providing conditions for performance of open heart operations, and it can be used in surgical repair of congenital cardiac defects.