Extracorporeal membrane oxygenation (ECMO) for support of adult patients with acute lung failure has been a vigorously debated topic among critical care professionals. As researchers continue to investigate its risks and benefits, indications for use are slowly expanding. Increasing wait times for lung transplants and the poor outcomes associated with endotracheal intubation warrant new support strategies for patients with end-stage lung disease. The authors of an article published in the April 2012 issue of the American Journal of Respiratory and Critical Care Medicine examined the role of ECMO as a bridge to lung transplantation.

In a retrospective, single-center study, the authors studied complications and outcomes for 26 awake patients who were treated with ECMO prior to lung transplantation and compared the findings with a historical control group of 34 patients from the same institution who were bridged to lung transplant with mechanical ventilation (MV). Both sets of patients had life expectancies of 24 to 48 hours before initiation of ECMO or MV. Indications for ECMO included severe hypoxemia with arterial oxygen saturation less than 80%, right ventricular failure despite maximum medical therapy with accompanying hypotension and end-organ failure, and hypercapnia with altered mental status secondary to respiratory acidosis. Venovenous ECMO was used in patients with hypercapnia or hypoxemia and stable hemodynamics, while venoarterial ECMO was employed for those patients with right ventricular failure.

The patient groups were similar in terms of age, gender, comorbid disease, presence of pulmonary hypertension, and disease severity. Duration of bridging therapy (nine days on ECMO vs. 15 days on MV, P = 0.25) was also comparable. Seven of 26 patients in the ECMO group required the addition of MV prior to lung transplant. Six patients in the ECMO group and 10 patients in the MV group died before transplantation could be performed. Patients treated with MV who survived to hospital discharge had longer intensive care unit lengths of stay, more days spent on the ventilator following lung transplant, and prolonged postoperative hospital courses. Survival at six months post-transplant was higher in patients bridged with ECMO (80%) than in those treated with MV (50%) (P = 0.02). Complications of ECMO included bleeding and secondary intubations due to airway compromise or power failure. Patients who required secondary intubation while on ECMO before transplantation achieved a six-month survival rate of 43%.

Limitations of this study include a small sample size, single-institution experience based on retrospective data, and comparison with a historical group rather than a parallel control group. The potentially fatal complications associated with ECMO mandate that this modality be considered only at institutions with the appropriate experience and after standardized, noninvasive therapies have failed. Despite these limitations, this study adds further information to the ECMO debate and highlights a possible alternative to MV for those awaiting lung transplantation.

Concise Critical Appraisal is a regular feature authored by SCCM member Samuel M. Galvagno Jr., DO. Each installment highlights journal articles most relevant to the critical care practitioner.

Special thanks to Rebecca Duncan, MD, who contributed to this installment of Concise Critical Appraisal. Duncan is a fellow in trauma and critical care medicine at the University of Maryland R. Adams Cowley Shock Trauma Center in Baltimore, Maryland, USA.