Abstract
Spontaneous breathing during mechanical ventilation has long been recognized as beneficial, since spontaneous breathing increases aeration and oxygenation and preserves diaphragmatic muscle function. Spontaneous effort also reduces the pleural pressure and increases the transpulmonary pressure. Unlike the situation in normal lungs, however, the change in transpulmonary pressure is not uniformly transmitted in injured lungs, resulting in the pendelluft phenomenon. Clinical data suggest that the vigorous effort of spontaneous breathing may cause or worsen acute lung injury by increasing the transpulmonary pressure and pendelluft phenomenon. Ventilator strategies for patients with acute respiratory distress syndrome with and without spontaneous breathing should not be conflicting, but rather compatible, if spontaneous effort is adequately controlled.
