Objective: To investigate whether deep (<20 degrees C) hypothermia is necessary in patients undergoing pulmonary endarterectomy for chronic thromboembolic pulmonary hypertension.
Methods: Between January 2004 and February 2005, 30 patients (New York Heart Association (NYHA) class III or IV) were randomly assigned to increasing (1 degrees C) levels of moderate (28-32 degrees C) hypothermic cardiopulmonary bypass (CPB), each study group including six patients. Primary study endpoint was adverse neurological outcome. Overall preoperative total pulmonary vascular resistance was 1110+/-192 dynes cm(-5).
Results: Mean CPB and cross-clamp times, and core temperature at the time of circulatory arrests were 129+/-39 min and 92+/-24 min, and 30.1+/-1.5 degrees C, respectively. Circulatory arrest was induced 2+/-0.7 times and its mean total duration was 10.3+/-5.2 min (range, 2-19 min). Postoperatively, three patients (10%) belonging to the 31 degrees C (n=1) and 32 degrees C (n=2) groups suffered from temporary neurological dysfunction. Postoperative mechanical ventilatory support and ICU stay were 26.3+/-18.9 h and 6.6+/-8.5 days, respectively, and uninfluenced by degree of hypothermia. There were no lung reperfusion injuries or any other major complications. All patients had a significant hemodynamic improvement.
Conclusion: Results suggest that pulmonary endarterectomy can be safely performed with moderate hypothermia and short periods of circulatory arrests without the need of profound hypothermia.