Morbid obesity's impact on COVID-19 patients requiring venovenous extracorporeal membrane oxygenation: The covid-19 critical care consortium database review

Abstract

Introduction: Obesity is associated with a worse prognosis in COVID-19 patients with acute respiratory distress syndrome (ARDS). Veno-venous (V-V) Extracorporeal Membrane Oxygenation (ECMO) can be a rescue option, however, the direct impact of morbid obesity in this select group of patients remains unclear.Methods: This is an observational study of critically ill adults with COVID-19 and ARDS supported by V-V ECMO. Data are from 82 institutions participating in the COVID-19 Critical Care Consortium international registry. Patients were admitted between 12 January 2020 to 27 April 2021. They were stratified based on Body Mass Index (BMI) at 40 kg/m². The endpoint was survival to hospital discharge.Results: Complete data available on 354 of 401 patients supported on V-V ECMO. The characteristics of the high BMI (>40 kg/m²) and lower BMI (≤40 kg/m²) groups were statistically similar. However, the 'high BMI' group were comparatively younger and had a lower APACHE II score. Using survival analysis, older age (Hazard Ratio, HR 1.49 per-10-years, CI 1.25-1.79) and higher BMI (HR 1.15 per-5 kg/m² increase, CI 1.03-1.28) were associated with a decreased patient survival. A safe BMI threshold above which V-V ECMO would be prohibitive was not apparent and instead, the risk of an adverse outcome increased linearly with BMI.Conclusion: In COVID-19 patients with severe ARDS who require V-V ECMO, there is an increased risk of death associated with age and BMI. The risk is linear and there is no BMI threshold beyond which the risk for death greatly increases.

Keywords: COVID-19; acute respiratory distress syndrome; extracorporeal membrane oxygenation; morbid obesity.

Graphical Abstract

Figure 1.

Patient selection algorithm. BMI at 40 kg/m² threshold. ARDS: acute respiratory distress syndrome; BMI: body mass index.

Figure 2.

Study group characteristics, BMI at 40 kg/m² threshold: There was a trend towards the high BMI group being younger and with a lower APACHE II score. BMI: body mass index.

Figure 3.

Cumulative probabilities over time of survival, stratified by a BMI threshold of 40 kg/m²: The cumulative survival curves show no significant difference at the BMI threshold of 40 kg/m², however, the risk of death is a continuous variable (HR 1.15 per-5 kg/m² increase, CI 1.03–1.28). BMI: body mass index.

Figure 4.

Sensitivity analyses show that variability between sites was small and no one site overly influenced outcomes.