EFFECTS OF UPPER OR LOWER ABDOMINAL SURGERY ON DIAPHRAGMATIC FUNCTION

Patients undergoing upper abdominal surgery develop a restrictive pattern of pulmonary dysfunc-tion (Craig, 1981). Vital capacity (VC) is reduced to approximately 40-50 % of its preoperative value, and remains decreased for at least 1 week (Craig, 1981). This reduction in VC is associated with a marked decrease in functional residual capacity, arterial hypoxaemia and, frequently, lower lobe atelectasis. Although the mechanisms producing these effects are still under investiga-tion, diaphragmatic dysfunction has been demon-strated after upper abdominal surgery (Ford et al., 1983; Simmoneau et al., 1983) and has been suspected to be the main determinant of these alterations in function. In contrast, much lesser changes in VC, and fewer pulmonary complica-tions, are observed after lower abdominal surgery (Craig, 1981). It may, therefore, be interesting to compare the changes in diaphragmatic function and VC between patients undergoing upper or lower abdominal surgery. PATIENTS AND METHODS Twenty-seven patients undergoing abdominal surgery were selected; all were free from cardio-respiratory disease. Informed consent was ob-tained from each patient. In 23 patients, diaphrag-matic function and VC were determined before, and after, the surgical procedure. This group was subdivided into two subgroups according to the site of surgery. Group 1 consisted of 17 patients undergoing upper abdominal surgery involving the biliary tract or the stomach through a midline incision. Group 2 consisted of six patients under-going prostatectomy or hysterectomy through a midline suprapubic incision. In four additiona