Extracorporeal membrane oxygenation circuits in parallel for refractory hypoxemia in patients with COVID-19

Abstract

Objectives: Refractory hypoxemia can occur in patients with acute respiratory distress syndrome from COVID-19 despite support with venovenous (VV) extracorporeal membrane oxygenation (ECMO). Parallel ECMO circuits can be used to increase physiologic support. We report our clinical experience using ECMO circuits in parallel for select patients with persistent severe hypoxemia despite the use of a single ECMO circuit.

Methods: We performed a retrospective cohort study of all patients with COVID-19-related acute respiratory distress syndrome who received VV-ECMO with an additional circuit in parallel at Vanderbilt University Medical Center between March 1, 2020, and March 1, 2022. We report demographic characteristics and clinical characteristics including ECMO settings, mechanical ventilator settings, use of adjunctive therapies, and arterial blood gas results after initial cannulation, before and after receipt of a second ECMO circuit in parallel, and before removal of the circuit in parallel, and outcomes.

Results: Of 84 patients with COVID-19 who received VV-ECMO during the study period, 22 patients (26.2%) received a circuit in parallel. The median duration of ECMO was 40.0 days (interquartile range, 31.6-53.1 days), of which 19.0 days (interquartile range, 13.0-33.0 days) were spent with a circuit in parallel. Of the 22 patients who received a circuit in parallel, 16 (72.7%) survived to hospital discharge and 6 (27.3%) died before discharge.

Conclusions: In select patients, the additional use of an ECMO circuit in parallel can increase ECMO blood flow and improve oxygenation while allowing for lung-protective mechanical ventilation and excellent outcomes.

Keywords: acute respiratory distress syndrome; coronavirus disease 2019; extracorporeal membrane oxygenation; hypoxemic respiratory failure; parallel circuits.

Graphical abstract

VV-ECMO with the additional use of an ECMO circuit in parallel.

Figure 1

Parallel circuit cannulation for venovenous extracorporeal membrane oxygenation using bilateral femoral veins and bilateral internal jugular veins.

Figure 2

Parallel circuit cannulation for venovenous extracorporeal membrane oxygenation using bilateral femoral veins. Return from both circuits is through a single, large cannula placed in the internal jugular vein.

Figure 3

Median cardiac output of 10 patients over a 24-hour period before additional use of a second extracorporeal membrane oxygenation circuit in parallel. Vertical bars represent the interquartile range.

Figure 4

Overview of study and results. COVID-19, Coronavirus disease 2019; VV, venovenous; ECMO, extracorporeal membrane oxygenation.

Figure E1

Representative chest roentgenogram in 3 patients showing cannula positioning and progression during extracorporeal membrane oxygenation (ECMO) support: (A) after initial cannulation, (B) during use of parallel circuits, and (C) immediately after decannulation. ∗ Identifies the tips of drainage and reinfusion cannulas.