The Effects of Increased Abdominal Pressure on Lung and Chest Wall Mechanics During Laparoscopic Surgery

Abstract

Comment The authors found increased lung and chest wall impedances after insufflation of the abdominal cavity. The authors propose that the increased impedances will result in increased alveolar pressure, which will predispose to lung injury. However, if the mechanical lung injury is related to increased lung volume, as some investigators have proposed, then despite the increased impedances, the risk may not be any greater. I had one methodologic problem with the conduct of the study. To ensure that the lung returned to the same end-expiratory volume after each breath, the authors used the return of airway pressure to the set level of positive end-expiratory pressure (PEEP) as a trigger for the next bream. At higher frequencies, despite the return of airway pressure to the set level of PEEP, the intra-alveolar pressure may still be greater than the airway pressure, thus confounding the results. Zero end-expiratory flow may have been a better trigger.