Initiation of extracorporeal membrane oxygenation (ECMO) may result in decreases in lymphocyte numbers and function, which can be associated with increased severity of COVID-19. In a letter published online in The Lancet Respiratory Medicine, Dr. Brandon M. Henry from Cincinnati Children's Hospital Medical Center in Ohio urges caution when using ECMO in patients with COVID-19, especially in the face of lymphopenia. Given the recognized impact of ECMO on lymphocytes, along with the hypothesis that repletion of lymphocytes might be key to recovery from COVID-19, he recommends close monitoring of lymphocyte counts in patients receiving ECMO. Dr. Henry also cites a paper in Intensive Care Medicine by Dr. Quirong Ruan and colleagues from Tongji Medical College, Wuhan, China, reporting significantly higher interleukin-6 concentrations in COVID-19 non-survivors, compared with survivors. (https://bit.ly/2WJCdJw) IL-6 concentrations are also elevated during ECMO, he points out, and these concentrations are inversely correlated with survival in children and adults. Elevated IL-6 concentrations in the lung induced by ECMO have been associated with parenchymal damage in animal models. While cautioning that the data are not robust enough to discourage the use of ECMO in COVID-19, he says "the immunological status of patients should be considered when selecting candidates for ECMO." "More reports are needed to understand the potential benefits or harms of extracorporeal life support in severe COVID-19 and future authors should be encouraged to provide more data for this subset of patients," Dr. Henry concludes. "Clinicians should consider tracking both lymphocyte count and IL-6 during ECMO to monitor patient status and prognosis." Source
