• Postoperative atelectasis has been treated with inspiratory maneuvers in an attempt to increase functional residual capacity. We compared the effect of intermittent positive pressure breathing (IPPB), incentive spirometry, and 5-cm H2O positive end-expiratory pressure (PEEP) applied with a face mask on the transpulmonary pressure (PL) at the end of expiration of eight patients 24 to 34 hours after aortocoronary bypass graft insertion. Intermittent positive pressure breathing and PEEP increased expiratory PL during therapy. After IPPB, expiratory PL fell below control values and then returned toward, but did not reach, control values. After PEEP was discontinued, expiratory PL returned to control values within the next 30 minutes. The results suggest that face-mask PEEP will increase functional residual capacity, that incentive spirometry has little or no effect, and that IPPB may decrease lung volume after treatment.
(Arch Surg 1981;116:861-863)