187: Reconfiguration rate and flow dynamics in ECMO supported patients with ARDS

Background: The extracorporeal membrane oxygenation (ECMO) flow rate needed to adequately support patients with acute respiratory distress syndrome (ARDS) is variable. Meeting the oxygen delivery needs of these patients occasionally requires higher than average flow thus necessitating the insertion of an additional drainage cannula. This study addresses the frequency with which ARDS patients on ECMO require an additional drainage cannula and whether this need is related to initial cannula selection. Flow dynamics before and after reconfiguration are analyzed. Methods: Retrospective chart review was performed on patients cannulated to venovenous (VV) ECMO at a high volume ECMO center from March 1, 2020 to January 1, 2022. Incidence of reconfiguration from VV to veno-venovenous (VVV) ECMO as well as flow dynamics before and after reconfiguration were analyzed. A Fischer exact test was used to compare the reconfiguration rates and a nonlinear mixed effects model with autoregression correlation was used to compare the pre and post-cannulation states Results: A higher proportion of patients who received a cannula less than 29Fr in size required reconfiguration when compared to patients who received 29Fr cannula (23.26% vs. 6.25%, p=0.259). Mean flow after reconfiguration was higher than before reconfiguration by 0.335 L/min (p<0.00001). Mean negative drainage pressure was less negative after reconfiguration than before by 18.474 mmHg (p<0.00001). Conclusions: Cannulation with the largest available drainage cannula is the most optimal cannulation strategy to avoid impaired oxygen delivery requiring reconfiguration.