Pulmonary endarterectomy for chronic thromboembolic pulmonary hypertension: is deep hypothermia required?

To investigate whether deep (<20 degrees C) hypothermia is necessary in patients undergoing pulmonary endarterectomy for chronic thromboembolic pulmonary hypertension.

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).

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.

Results suggest that pulmonary endarterectomy can be safely performed with moderate hypothermia and short periods of circulatory arrests without the need of profound hypothermia.