An investigation into the contributing factors to survival of COVID-19 induced ARDS patients supported by veno-venous ECMO.

Abstract

This study aimed to identify characteristics associated with survival and prognosis during/post Veno-Venous Extracorporeal Membrane Oxygenation (VV-ECMO) therapy, a modality of treatment suggested by the World Health Organisation (WHO), in patients with COVID-19 induced Acute Respiratory Distress Syndrome (ARDS). Also, we aimed to identify pre and peri-measures that have an influence on and affect the survival times of this cohort and to see how changes in these variables influenced the risk of not surviving ECMO treatment. A retrospective observational study on 93 consecutive patients with confirmed COVID-19 induced acute respiratory distress syndrome (ARDS) supported by Extra Corporeal Membrane Oxygenation (ECMO) was carried out. 49/93 (52.7%) patients survived to hospital discharge. All proposed objectives were met to provide a valuable insight into the efficacy of ECMO for this specific cohort. Non-survivors, in comparison to survivors, were found to have significantly (p<0.05) higher: Pre-ECMO International normalized ratios (INR), carbon dioxide partial pressure (pCO2), Acute Kidney Injury (AKI) scores, blood urea levels and peri-ECMO fresh frozen plasma (FFP) and platelet transfusion volumes. Also, lower pre-ECMO peak inspiratory pressures (PIP), mean blood pressure, saturation of arterial oxygen (SaO2), blood bicarbonate levels (HCO3), blood pH and fewer trials off ECMO with shorter combined trial off times. Patients that did not survive were more likely to have renal impairment and have received peri-ECMO haemofiltration. Poor prognosis was significantly associated with receiving pre-ECMO nitric oxide, renal impairment, AKI staging score of 2 or 3, peri-ECMO haemofiltration, receiving transfusions of albumin, red blood cells (RBC), Fresh Frozen Plasma (FFP), platelets, cryoprecipitate and the ABO blood group B, pre-ECMO high CO2, blood lactate, and lower blood pH. It was seen that commonly used mortality scores may not be of use in a COVID-19 cohort of ECMO patients. These findings indicated that the initiation of ECMO needs to be implemented prior to metabolic derangements, renal and fulminant respiratory failure. By utilising the findings of this study, one can make best use of finite resources to provide the greatest utility at a time of excessive demand. As well as filling a known knowledge gap in the use of VV-ECMO for COVID-19 induced ARDS patients, it also highlights further requirements to investigate the use of ECMO in the ARDS setting