Effect of positive end-expiratory pressure on excessive mediastinal bleeding after cardiac operations. A controlled...

The efficacy of mechanical ventilation with positive end-expiratory pressure (PEEP) in the therapy of excessive mediastinal hemorrhage following cardiac operations remains unproved. One hundred thirty-nine patients undergoing elective myocardial revascularization were divided into two groups on the basis of preoperative hematologic evaluation: Group I, 94 patients with no history of hematologic abnormalities and a normal coagulation profile; Group II, 45 patients with a recent use of antiplatelet medications and/or a prolonged template bleeding time. Both groups were randomized to receive mechanical ventilation with 10 cm H2O of PEEP or no PEEP beginning 1 hour after operation and continuing for an 8 hour study period. Mean blood loss at 8 hours (BVt) was not significantly different between PEEP and control patients in either group. Fifty-seven patients in Groups I and II had mediastinal bleeding in excess of 180 ml/hr at the initiation of the study period. There was no significant difference in mean BVt or mean hourly chest tube output with or without PEEP in either group of this subset. In view of the lack of demonstrable efficacy in decreasing mediastinal hemorrhage and the potential of adverse hemodynamic effects, PEEP should no longer be used for therapy of excessive bleeding after cardiac operation, especially in patients with reduced cardiac reserve.