Extracorporeal Membrane Oxygenation in Coronavirus Disease 2019-Associated Acute Respiratory Distress Syndrome: an Initial US Experience at a High-volume Centre

The use of extracorporeal membrane oxygenation (ECMO) as salvage therapy in the most severe cases of acute respiratory distress syndrome (ARDS) has been associated with reduced mortality, particularly at highvolume centres.We report a case series of seven patients with coronavirus disease 2019 (COVID-19)-associated ARDS treated with ECMO.In select COVID-19 patients suffering from severe ARDS refractory to conventional therapy, ECMO might be an outcome altering therapy.Respiratory ECMO Survival Prediction (RESP) score appears to be a reliable prognostication tool in selecting COVID-19 patients most likely to benefit from ECMO.Early and frequent evaluation of critically ill COVID-19 patients for ECMO therapy could facilitate timely initiation, and ultimately, favourable outcomes.ECMO is a finite resource, and thus must be used judiciously, especially in the midst of a pandemic where all resources are stretched thin.ECMO is a well-established salvage therapy in treatment of severe refractory ARDS.Venous-venous ECMO (VV-ECMO) is a modified cardiopulmonary bypass system in which venous blood is removed from the body and circulated through an artificial membrane lung and has successfully been deployed in the treatment of patients with severe ARDS.The initiation of VV-ECMO allows for ultra-lung protective/'lung rest' ventilation in ARDS patients with poor lung compliance.During the H1N1 influenza pandemic, a meta-analysis of 266 patients with severe ARDS supported with VV-ECMO showed a survival rate of 72.5%, albeit with prolonged hospitalisations. 1 While previous reports on VV-ECMO in ARDS are encouraging, initial reports of its use in Chinese COVID-19 patients have been less promising.Of the six patients placed on ECMO in Wuhan, China, only one survived to hospital discharge. 2In Shanghai, only four of eight patients survived to ECMO decannulation. 3 Early US data are similarly grim.A compiled study of 32 patients from nine different centres in the US showed a mortality rate of 31%, with 53% patients still on ECMO after 3 weeks. 4However, there remains a paucity of literature on its utilisation and efficacy in the treatment of COVID-19-associated ARDS, especially among US patients.Methods Baylor-St Luke's Medical Center is a large, academic quaternary hospital with 661 beds in the Texas Medical Center, Houston, TX, US.It serves as a centre for advanced heart failure and heart transplantation, with a robust volume of mechanical circulatory support, including ECMO (approximately 100-150 per year).We present a case series of seven consecutive polymerase chain reaction-confirmed diagnoses of COVID-19 patients admitted to our centre between 29 March and 8 May 2020.Prior to the initiation of ECMO, patients were screened for major comorbidities, with an absolute age cut-off age of >65 years and predicted survival based on a RESP score of <40%. ResultsThe mean age of our cohort was 45 years and comprised three men and four women.The most common baseline comorbidities included obesity (four patients, mean BMI: 35.7) and hypertension (three patients).There was no history of smoking, chronic obstructive pulmonary disease, asthma, chronic kidney disease or coronary artery disease.Only one of seven (14%) patients had a prior history of diabetes mellitus, heart failure or angiotensin-converting enzyme/angiotensin receptor blocker use.A comprehensive list of baseline characteristics is provided in Table 1.Patients presented to the hospital on average 7 days after onset of symptoms, spent 1.9 days in hospital prior to intubation and 3.7 days from the time of intubation to the initiation of ECMO.All had refractory hypoxia, despite lung-protective ventilation; neuromuscular blockade; inhaled epoprostenol; and underwent prone position ventilation.Average positive end-expiratory pressure was 16.9 mmHg, with tidal volume of 5.75 ml/kg of ideal body weight and PaO 2 /FiO 2 ratio of 84.5 prior to ECMO initiation.There was evidence of left and right ventricle dysfunction based on gross visual assessment in one patient, with a mean left ventricular ejection fraction of 55 ± 9%.The average RESP score was 3.7 at the time of ECMO cannulation.Hydroxychloroquine (six patients), azithromycin (seven patients) and hydrocortisone (100%) Disclosure: The authors have no conflicts of interest to declare.