LAS VEGAS – The evidence supporting use of extracorporeal membrane oxygenation for treating adult patients with severe hypoxic lung failure remains uncompelling, according to Dr. Alan H. Morris.
He particularly advised against widespread use of extracorporeal membrane oxygenation (ECMO) in patients who have severe acute respiratory distress syndrome secondary to H1N1 influenza infection, as there is also no evidence that H1N1 patients treated with ECMO had better outcomes than those treated with standard ventilation support.
Dr. Alan H. Morris
"We need results from a credible randomized controlled trial to define the conditions surrounding ECMO, before ECMO becomes a routine therapy option," said Dr. Morris, a pulmonologist and professor of medicine at the University of Utah and Intermountain Health Medical Center in Salt Lake City.
"There are indications and applications of extracorporeal support that are straightforward," such as when it is used intraoperatively, he said. But for patients with severe hypoxic lung failure, "I do not see compelling evidence that extracorporeal support is followed by more favorable outcomes than other approaches that are used," he said in an interview. "The evidence from the H1N1 novel influenza epidemic indicates to me that survival appears to be roughly the same with or without extracorporeal support," he added. "We do not offer ECMO as treatment for adult patients with severe hypoxic lung failure in my hospital."
The only two studies that examined the efficacy of ECMO in rigorously controlled clinical trials, published as reports in 1979 and in 1994, both failed to show that ECMO improved patient survival, he noted (JAMA 1979;242:2193-6; Am. J. Respir. Crit. Care Med. 1994;149:295-305). More recent results from a British multicenter randomized trial with 180 adults with severe respiratory failure claimed to show evidence that patient survival with ECMO surpassed survival with usual care (Lancet 2009;374:1351-63). But the newer study had the flaw of failing to define the usual care received by the control patients. In addition, the control patients were distributed to many centers, while all the ECMO patients received their treatment at one center, Dr. Morris said. The conventional ventilation that control patients received could be whatever their attending intensivist thought appropriate.
"How does a clinician know which patients will benefit [from ECMO] without knowing what was conventional treatment?" he said.
To assess the impact of ECMO in patients with acute respiratory distress secondary to H1N1 infection, Dr. Morris summarized data reported on 150 patients in a University of Michigan registry; 14 patients seen in Salt Lake County, Utah, and reported last year in a paper at the American Thoracic Society; a series of 68 patients reported from Australia and New Zealand (JAMA 2009;302:1888-95); and 896 U.S. patients entered into a registry of the National Heart, Lung, and Blood Institute during April 2009 to April 2010. These data showed a consistent pattern of no improved survival with ECMO treatment in H1N1 patients, compared with H1N1 patients who did not receive ECMO, Dr. Morris said.
He also expressed concern that a well-designed study to compare modern ECMO with other ventilation support methods would be a challenge. A major problem is that the physicians "who have ECMO skills are convinced of its efficacy. Those who do ECMO don’t believe that better testing is needed," Dr. Morris said.
He reported having no relevant financial disclosures.