Passage of air from the bronchi into the pleural space during mechanical ventilation results in pneumothorax, for which prompt chest-tube placement is necessary. Positive airway pressure and external chest-tube suction establish a pressure gradient that may allow air to escape continuously in a persistent bronchopleural air leak (PBL). Although its significance in the natural history and prognosis of severe acute respiratory failure (ARF) has not been established, the presence of a PBL can lead to persistent lung collapse, loss of effective tidal volume and positive end-expiratory pressure (PEEP), seeding of the pleural space with airway organisms, and intractable respiratory acidosis. Clinicians have tried several therapeutic approaches intended to minimize the bronchopleural pressure gradient, maintain gas exchange, and reinflate the affected lung. In addition to adjustments in ventilator settings and external suction, these include the application of PEEP to the chest tube, occlusion of the tube during part of the ventilator cycle, independent ventilation of the two lungs, and high-frequency ventilation. Direct closure or plugging of the leak site has also been attempted. So far there is no single best therapy, and patients with severe PBL continue to have a poor prognosis, perhaps owing to the severity of the underlying respiratory dysfunction as much as to the leak. Careful general respiratory care, early vigorous treatment of ARF, and ventilator management aimed at reducing the factors that predispose to pneumothorax and PBL may reduce the incidence of this often devastating complication.
David J Pierson (Thu,) studied this question.