Prophylactic positive end-expiratory pressure and reduction of postoperative blood loss in open-heart surgery

Various strategies have been introduced to minimize transfusion requirements in cardiac surgery. One strategy is the use of positive end-expiratory pressure (PEEP) postoperatively. Currently, PEEP is used in many centers to control increased mediastinal chest-tube drainage. The purpose of this study was to determine whether the prophylactic application of a PEEP of 10 cm H2O compared with a PEEP of 5 cm H2O in the immediate postoperative period reduces mediastinal chest-tube output without causing clinically significant hemodynamic compromise.

We prospectively studied 84 elective coronary artery bypass grafted patients and randomized treatment groups to a PEEP of 5 or 10 cm H2O. Forty-four patients were assigned a PEEP of 5 cm H2O and 40 patients received a PEEP of 10 cm H2O.

Preoperative, intraoperative, and postoperative demographics were similar between groups. There was no statistically significant difference between the 5 cm H2O PEEP group and the 10 cm H2O PEEP group with regard to chest-tube output at 6 hours, at 24 hours, or in total output. There was no statistical difference in hemoglobin levels immediately postoperatively, at 8 hours, or at 36 hours.

This study demonstrates that the use of postoperative PEEP levels of 10 cm H2O, although safe, does not reduce chest-tube output or transfusion requirements.