Extracorporeal membrane oxygenation for pandemic H1N1 2009 respiratory failure

Severe respiratory failure related to infection with the pandemic influenza A/H1N1 2009 virus is uncommon but possibly life-threatening. If, in spite of maximal conventional critical care, the patient's condition deteriorates, extracorporeal membrane oxygenation (ECMO) may be a life-saving procedure.

An observational study approved by the local ethics committee was carried out. Data from all patients treated with ECMO at the ECMO Center Karolinska for influenza A/H1N1 2009-related severe respiratory failure were analyzed. The main outcome measure was survival three months after discharge from our department.

Between July 2009 and January 2010, 13 patients with H1N1 2009 respiratory failure were treated with ECMO. Twelve patients were cannulated for veno-venous ECMO at the referring hospital and transported to Stockholm. One patient was cannulated in our hospital for veno-arterial support. The median ratio of the arterial partial oxygen pressure to the fraction of inspired oxygen (P/F ratio: PaO2 /FiO2) before cannulation was 52.5 (interquartile range 38-60). Four patients were converted from veno-venous to veno-arterial ECMO because of right heart failure (three) or life-threatening cardiac arrhythmias (one). The median maximum oxygen consumption via ECMO was 251 ml/min (187-281 ml/min). Twelve patients were still alive three months after discharge; one patient died four days after discharge due to intracranial hemorrhage.

Patients treated with veno-venous or veno-arterial ECMO for H1N1 2009-related respiratory failure may have a favorable outcome. Contributing factors may include the possibility of transport on ECMO, conversion from veno-venous (v-v) or veno-arterial (v-a) ECMO if necessary, high-flow ECMO to meet oxygen requirements and active surgery when needed.