Objective. To evaluate the prevention of respiratory complications after abdominal surgery by a comparison of a global policy of incentive spirometry with a regimen consisting of deep breathing exercises for low risk patients and incentive spirometry plus (BMJ 1996;312:148-53) Postoperative respiratory morbidity continues to be a tention), a stiffened abdominal wall and, possibly, diaphragmatic dysfunction. 1 These pathophysiological major factor in the utilisation of resources and maintenance of hospitalisation after major surgery. The inchanges underpin the events in the immediate postoperative period and morbidity and mortality depend troductory article draws attention to this but, as the aetiology, prevention and management are multiupon their severity. The main factor behind all these events, and the one which is most amenable to modfactorial, the approach of this review to this subject has been broadened. ulation, is severe postoperative pain. This discussion paper will review the effects of an The incidence of pulmonary complications is higher after upper abdominal or chest surgery than operations abdominal incision, its analgesic management, and postoperative physiotherapy on the generation of poston other parts of the body. These wounds produce a severe and prolonged alteration in pulmonary mechoperative respiratory complications. anics.1 Impaired ventilation and ineffective expectoration result in a postoperative failure of expansion or progression of collapse of lung segments, thereby encouraging infection. The ensuing shunt with venous Effects of anaesthesia and an abdominal incision on pulmonary physiology admixture results in hypoxaemia. Postoperative oxygen supply may therefore falter while oxygen demands are Some great minds have pondered the problem of postoperative complications. Pasteur, Haldane and Beecher increased due to metabolic hypermetabolism and hypercatabolism of the neuroendocrine stress response to were all convinced of the importance of active collapse of the lung after abdominal operations with shallow trauma.2 At the same time the work of breathing is increased due to the need for increased alveolar ventbreathing as the major cause of postoperative hypoxia and pulmonary complications.3-5