Extracorporeal Membrane Oxygenation for ARDS in Adults

Daniel Brodie, M.D., and Matthew Bacchetta, M.D.

N Engl J Med 2011; 365:1905-1914November 17, 2011

Article
References: This Journal feature begins with a case vignette that includes a therapeutic recommendation. A discussion of the clinical problem and the mechanism of benefit of this form of therapy follows. Major clinical studies, the clinical use of this therapy, and potential adverse effects are reviewed. Relevant formal guidelines, if they exist, are presented. The article ends with the authors' clinical recommendations.
A 41-year-old woman presents with severe community-acquired pneumococcal pneumonia. Chest radiography reveals diffuse bilateral infiltrates, and hypoxemic respiratory failure develops despite appropriate antibiotic therapy. She is intubated and mechanical ventilation is initiated with a volume- and pressure-limited approach for the acute respiratory distress syndrome (ARDS). Over the ensuing 24 hours, her partial pressure of arterial oxygen (PaO₂) decreases to 40 mm Hg, despite ventilatory support with a fraction of inspired oxygen (FIO₂) of 1.0 and a positive end-expiratory pressure (PEEP) of 20 cm of water. She is placed in the prone position and a neuromuscular blocking agent is administered, without improvement in her PaO₂. An intensive care specialist recommends the initiation of extracorporeal membrane oxygenation (ECMO).
The Clinical Problem
ARDS is characterized by the acute onset of hypoxemia and bilateral pulmonary infiltrates that are consistent with pulmonary edema but without evidence of left heart failure.1 There are more than 140,000 cases of ARDS in the United States annually.2 In clinical trials involving patients with acute lung injury and ARDS, mortality remains high (22 to 41%).3-9
There is no consensus definition of severe ARDS, so precise estimates of the mortality associated with more severe presentations of ARDS do not exist. However, the mortality is almost certainly higher with severe ARDS. Nearly 20% of all patients with ARDS ultimately die of refractory hypoxemia.10 Oxygenation itself is not clearly predictive of poor outcomes,11 although there is some evidence that a lower ratio of PaO₂ to FIO₂ is predictive of death, especially over time.5,7,12-18
Many survivors of ARDS have a significantly diminished quality of life that may persist for at least 5 years.19 Average annual medical costs for survivors are two to four times those for a healthy person.20