POSITIVE END-EXPIRATORY PRESSURE VENTILATION AFTER OPEN-HEART SURGERY

Abstract

Thirty-seven patients were studied after open-heart surgery in relation to the effect of positive end-expiratory pressure ventilation (PEEP) as compared to routine intermittent positive pressure ventilation (IPPV) with the Engstrom Respirator. The patients were divided in two groups with 21 patients receiving PEEP and 16 IPPV. Arterial oxygen tensions and inspiratory oxygen fractions were determined 1 h after surgery and 1 day later. During the first postoperative night, the respirator settings were not changed. Inspired oxygen fractions were kept constant. PEEP between + 5 to + 10 cmH2O was used. In 11 patients, functional residual capacity (FRC) was measured preoperatively and on the first postoperative day. Statistical analyses showed no significant changes in arterial oxygen tension or in the alveolar-arterial oxygen differences between the two groups. FRC was slightly disminished, but no correlation was found in relation to changes in arterial oxygen tensions. It is concluded that after uneventful open-heart surgery, when careful attention is paid to maintenance of circulation and avoidance of overhydration, PEEP does not have any advantage over IPPV with a volume controlled ventilator. PEEP should, therefore, be reserved for patients with interstitial pulmonary oedema with alveolar “oxygen-block” or those in whom measures to improve pulmonary perfusion have not succeeded.