Characteristics of Delirium and Its Association with Sedation and In-Hospital Mortality in COVID-19 Patients on Veno-venous Extracorporeal Membrane Oxygenation

Abstract

Abstract Background Veno-venous extracorporeal membrane oxygenation (VV-ECMO) has been used in patients with COVID-19 acute respiratory distress syndrome (ARDS). We aim to assess the characteristics of delirium and describe its association with sedation and in-hospital mortality. Methods We retrospectively reviewed adult patients on VV-ECMO for severe COVID-19 ARDS in the Johns Hopkins Hospital ECMO registry in 2020-2021. Delirium was assessed by the Confusion Assessment Method for the ICU when patients scored -3 or above on Richmond Agitation-Sedation Scale (RASS). Primary outcomes were delirium prevalence while on VV-ECMO and categorization of VV-ECMO days based on delirium status. Results Of 47 patients (median age=51) with 6 in a persistent coma, 40 of the remaining 41 patients (98%) had ICU delirium. Delirium in the survivors (n=21) and non-survivors (n=26) was first detected at a similar time point (day 9.5[5, 14] vs. 8.5[5, 21], p=0.56) with similar total delirium days (9.5[3.3, 16.8] vs. 9.0[4.3, 28.3], p=0.43), but the RASS scores on VV-ECMO were numerically lower in non-survivors (-3.72[-4.42, -2.96] vs. -3.10[-3.91, -2.21], p=0.06). Non-survivors had significantly prolonged median delirium days (27.3[17.4, 46.4] vs. 17.0[9.9, 28], p=0.04), delirium-unassessable days on VV-ECMO with a RASS of -4/-5 (23.0[16.3, 38.3] vs. 17.0[6, 23], p=0.03), and total VV-ECMO days (44.5[20.5, 74.3] vs. 27.0[21, 38], p=0.04). The proportion of delirium-present days correlated with RASS (r=0.64, p<0.001), proportion of days with a neuromuscular blocker (r=-0.59, p=0.001) and delirium-unassessable exams (r=-0.69, p<0.001), but not with overall ECMO duration (r=0.01, p=0.96). Average daily dosage of delirium-related medications on ECMO days did not differ significantly between survivors and non-survivors. On multivariable logistic regression, proportion of delirium days was not associated with mortality. Conclusions Longer duration of delirium was associated with lighter analgosedation and shorter paralysis, but the condition did not discern in-hospital mortality. Future studies should evaluate analgosedation and paralytic strategies to optimize delirium, sedation level, and outcomes.