chapter  21
18 Pages

A Critical Review of RCTs of Tidal Volume Reduction in Patients with ARDS and Their Impact on Practice

WithPeter C. Minneci, Katherine J. Deans, Steven M. Banks, Charles Natanson, Peter Q. Eichacker

Critically ill patients requiring mechanical ventilation frequently develop

the acute respiratory distress syndrome (ARDS) (1,2). Over the past 15 years,

improvements in ventilatory management and other supportive care mea-

sures have led to a decreased mortality related to ARDS. However, the mortality rate in patients with ARDS remains high at 30% to 40% (3). This

devastating syndrome results in decreased lung compliance, requiring ven-

tilation with a higher airway pressure to maintain tidal volume (4). Patients

with ARDS are at risk for developing further lung injury secondary to the

potentially harmful effects of mechanical ventilation. Ventilator-induced

lung injury (VILI) can develop secondary to increased pressure and/or vol-

ume in the alveoli (5,6). Barotrauma secondary to increased pressure

within the alveoli can lead to alveolar rupture, while volutrauma secondary to increased volume within the alveoli can lead to alveolar overdistention.

Animal studies of mechanical ventilation have demonstrated that increased

pressure and overdistention of the alveoli lead to increases in membrane

permeability, edema, and inflammation (7-9). These processes may then

lead to a worsening of the lung injury and deterioration of the lung function in patients with ARDS. Concerns over these harmful effects of mechanical

ventilation have led to the development of lung-protective ventilation stra-

tegies, which attempt to minimize VILI by lowering the tidal volume and

limiting airway pressure.