ECMO and Prone Position in Patients With Severe ARDS

To the Editor Use of prone ventilation in patients with acute respiratory distress syndrome (ARDS) decreases pulmonary arterial to venous shunt, improves respiratory system compliance, and reduces cyclical airspace opening/closing in dependent lung regions. In their randomized clinical trial of prone positioning in conjunction with extracorporeal membrane oxygenation (ECMO), Dr Schmidt and colleagues used ultraprotective lung ventilation (tidal volume ≤4 mL/kg) to achieve low airspace opening pressures. There were no attempts to vary either the tidal volume or the level of positive end-expiratory pressure to optimize respiratory system compliance in either posture (prone vs supine positioning). The low tidal volumes used would limit the extent to which ventilation in the prone position could open atelectatic areas, increase compliance, and improve ventilation, possibly accounting for their finding that prone positioning did not facilitate earlier weaning from ECMO. The low tidal volumes administered without use of periodic sigh breaths (i e, large inflations to or approaching total lung capacity) could also account for the frequent development of whole lung atelectasis that they observed, and this would further limit the ability of prone ventilation to reduce cyclical airspace opening and closing and time to weaning from ECMO.
Source: JAMA - Category: General Medicine Source Type: research