Diagnosis of pneumothorax complicating mechanical ventilation.

Pneumothorax developed in 4 patients as a complication of mechanical ventilation and the manifestations were different in each case. The first patient had had a previous pneumomediastinum with symptoms of chest pain and rise in blood pressure. The second became restless and "fought" the ventilator. The third had pneumothorax previously and developed tachycardia and arrhythmias, and the level of end-expiratory pressure in the manometer of the ventilator rose above the present level. In the fourth patient, subcutaneous and submucous emphysema were apparent before pneumothorax was diagnosed. Pneumothorax was diagnosed promptly in all these patients, permitting adequate management without additional complications.