Asymptomatic diaphragmatic defect--a post-operative problem.

A three-hour operation on the maxilla of a woman with an unrecognized large left diaphragmatic defect using narcotic-supplemented nitrous oxide anaesthesia resulted in near-complete compression of her left lung. The condition remained asymptomatic until post-operative shivering increased the patient's metabolic requirements, leading to signs of air hunger. Aspiration of large amounts of gas from the stomach promptly relieved all symptoms in spite of significant residual X-ray findings. It is important to keep in mind that the early post-operative period is usually one of intense metabolic activity rather than of rest. Patients who are unlikely to cope with such demand should be identified pre-operatively and supported prophylactically by ventilatory assistance, ample supply of metabolic substrates and judicious sedation.