Heart-lung machine may be considered for certain patients with H1N1 influenza with acute respiratory failure
Research Activities, November 2010, No. 363
Many young adults who contracted the novel 2009 influenza H1N1 virus were admitted to intensive care units with severe respiratory failure. A review of studies comparing different methods of getting oxygen into the lungs of such patients suggests that clinicians should consider extracorporeal membrane oxygenation (ECMO) along with other salvage therapies in patients failing conventional therapy. ECMO has been used for respiratory failure in different types of patients, but there are no clinical guidelines for its use in patients with the flu.
In this review of studies, the researchers found no randomized controlled trials of ECMO in flu patients. They did find an observational study of H1N1 flu patients in Australia and New Zealand that reported on 68 patients treated with ECMO, which uses a modified heart-lung machine (a mechanical pump to oxygenate and circulate the patient's blood), and 133 treated with mechanical ventilation (via a breathing tube) during winter in those countries. However, the two groups were not comparable because one group had more severe lung damage than the other.
To get additional information, the researchers combined the findings from three randomized trials of ECMO therapy conducted over 30 years, regardless of the origin of respiratory distress. This meta-analysis found a suggestive, but not statistically significant, reduction in deaths compared with patients not receiving ECMO. A more recent study randomly assigned 90 patients to ECMO therapy and 90 to conventional management (control group). The risk of death or severe disability at 6 months was a significant 31 percent less for the ECMO than the control group. However, the risk of death by 6 months just missed statistical significance. The study was funded in part by the Agency for Healthcare Research and Quality (HS18406).
More details are in "A systematic review to inform institutional decisions about the use of extracorporeal membrane oxygenation during the H1N1 influenza pandemic," by Matthew D. Mitchell, Ph.D., Mark E. Mikkelsen, M.D., M.S.C.E., Ingi Lee, M.D., M.S.C.E., and others in the June 2010 Critical Care Medicine 38(6), pp. 1398-1404.