A man who underwent right pneumonectomy for carcinoma required 9 hours of postoperative mechanical ventilation. After his trachea was extubated his blood gases and pH were normal. But the next day he developed fever and shortness of breath, with hypoxemia and hypercarbia. A day later he sustained respiratory arrest and was intubated and mechanically ventilated. A chest roentgenogram revealed mediastinal emphysema and rightward mediastinal shift. A thoracostomy tube was inserted and connected to underwater drainage, with continuous gas leakage from this tube confirming a bronchopleural fistula. Mechanical ventilation with large tidal volumes and a rapid rate prevented hypoxemia, but manipulation of ventilator set-tings did not prevent Paco2 from rising to 90 torr, indicating inadequate alveolar ventilation. The outlet of the underwater seal of the drainage bottle was pressurized during mechanical inspiration to prevent gas leakage from the right hemithorax. During exhalation, intrapleural pressure was lowered to release gas from the right hemithorax. This improved alveolar ventilation within 1 hour.
Crawford et al. (Mon,) studied this question.