Controversy exists regarding the routine use of aids to lung expansion in the prevention of pulmonary complications after abdominal surgery. We prospectively randomized 172 patients into 1 of 4 groups: the control group (44 patients) received no respiratory treatment, the IPPB group (45 patients) received intermittent positive pressure breathing therapy for 15 min 4 times daily, the IS group (42 patients) was treated with incentive spirometry 4 times daily, and the DBE group (41 patients) carried out deep breathing exercises under supervision for 15 min 4 times daily. Roentgenographic changes, observed 24 h after surgery, were comparable in the 4 groups (20.5 to 36.6%). Pulmonary complications were defined as the development of 3 or more of 6 new findings: cough, phlegm, dyspnea, chest pain, temperature greater than 38 degrees C, pulse rate more than 100 beats/min. The frequency of development of pulmonary complications was 48% in the control group, 22% in the IPPB group (p less than 0.05), 21% in the IS group (p less than 0.05), and 22% in the DBE group (p less than 0.05). Side effects of respiratory treatment were observed only in the IPPB group (18%; p less than 0.05). Hospital stay in patients undergoing upper abdominal surgery was significantly shorter in the IS group (mean +/- SD, 8.6 +/- 3 days) than in the control group (13 +/- 5 days). This difference was not observed for the other 2 treatment groups.(ABSTRACT TRUNCATED AT 250 WORDS)