Coached efforts at diaphragmatic breathing were assessed as a means of increasing diaphragmatic movement in postoperative patients. Inductive plethysmography was used to measure compartmental tidal volumes of the abdomen (Vab) and the chest (Vc) in eight women (aged 41 +/- 16 years) who had no history of cardiovascular or pulmonary disease. These patients were studied before and after (POD1,3) elective cholecystectomy. In preoperative studies, DB increased the supine value of Vab. The corresponding increase on POD1 represents a similar proportion of the resting value. The postoperative fall in resting and stimulated values of Vab is attributed to the known effects of abdominal surgery on diaphragmatic movement. Hence, DB warrants investigation as a method of prophylaxis against the pulmonary complications of surgery, because diaphragmatic movement is largely responsible for ventilation of the lower lung fields, where atelectasis and infection occur most often.