Cardiovascular Effects of Mechanical Ventilation and Positive End-Expiratory Pressure

Abstract

To the Editor.— There is one comment we would like to make on Dr Luce's 1 discussion of cardiovascular effects of mechanical ventilation (MV) and positive end-expiratory pressure (PEEP). He says that ventricular after-load may be appreciably elevated in patients with ARDS [adult respiratory distress syndrome] receiving MV and high levels of PEEP. While this statement may be true, it suggests that the use of PEEP in ARDS may raise right ventricular afterload to a higher level than the primary disease. This is not always true. In ARDS, lung volumes fall, and with the fall in lung volume, right ventricular afterload rises. Using PEEP in a patient with ARDS and low lung volumes may actually decrease vascular resistance and lower right ventricular afterload. Overdistention of the lung to higher than normal lung volumes may raise pulmonary vascular resistance. The effect of PEEP on pulmonary vascular resistance is, in part,