The chest wall in acute lung injury/acute respiratory distress syndrome

PURPOSE OF REVIEW: There has recently been renewed interest in the chest wall during mechanical ventilation, related to lung-protective ventilation strategies, as well as in the role of abdominal pressure in many facets of critical illness. The purpose of this review is to address relevant issues related to the chest wall and mechanical ventilation, particularly in patients with acute lung injury/acute respiratory distress syndrome. RECENT FINDINGS: In mechanically ventilated patients with acute lung injury, intra-abdominal pressure is an important determinant of chest wall compliance. With elevated intra-abdominal pressure, the compliance of the chest wall and total respiratory system is decreased, with a relatively normal compliance of the lungs. The lung compression effects of increased intra-abdominal pressure may lead to a loss of lung volume with atelectasis. An appropriate level of positive end-expiratory pressure is necessary to counterbalance this collapsing effect on the lungs. Also, the stiff chest wall results in a lower transpulmonary pressure during positive-pressure ventilation. SUMMARY: As chest wall compliance may have important clinical implications during positive-pressure ventilation, the physiology of this effect should be considered, particularly in patients with acute lung injury and increased abdominal pressure.