Time to Extubation With and Without COVID-19 Pneumonia

Background:

Coronavirus disease 2019-associated ARDS (or CARDS) often requires invasive mechanical ventilation. Early on during the pandemic there was a perception that CARDS was associated with prolonged mechanical ventilation. This retrospective study assessed the characteristics and outcomes of both ARDS and CARDS subjects during the first 6 months of the COVID-19 pandemic. The primary objective was to ascertain whether subjects with CARDS had a longer mechanical ventilation duration than other forms of ARDS.

Methods:

Between March 1st and August 12th, 2020, we identified a total of 73 subjects for inclusion with either CARDS (37) or ARDS (36) who were managed with the ARDSnet ventilator protocol. Exclusion criteria were: <18 years of age, required tracheostomy, ECMO or failed extubation < 48 h. IRB approval was obtained with a waiver of consent. Demographic and baseline clinical data were collected at ARDS onset (ARDS day 0), with subsequent longitudinal data collected on ARDS days 1–3, 5, 7, 10, 14, and 21. Comparisons were made using Wilcoxon rank sum test (continuous variables), Chi squared test (categorical variables) stratified by COVID-19 status. A Kaplan Meier plot was used for extubation, and the log rank test used to assess significance. A Cox proportional hazards model was used to estimate the adjusted hazard ratio for extubation. Alpha was set at 0.05.

Results:

At ARDS onset, those meeting severe criteria (Berlin definition) was similar between CARDS (24%) vs. ARDS (27%), P = 0.81. Median [IQR] mechanical ventilation duration was longer in CARDS vs. ARDS: 10 [6–20] vs. 4 [2–8] d, P <0.001) (Figure 1). In the Cox proportional hazard analysis COVID-19 pneumonia was independently associated with a 30% decrease in the rate of achieving unassisted breathing, but this was not statistically significant (P = 0.36, 95% CI -68% to 51%). However, the rate of achieving unassisted breathing significantly increased by 31% per 10 mL/H₂O increase in C_RS (P = 0.04, 95% CI 1% to 68%).

Conclusions:

MV days is prolonged in CARDS when compared to ARDS, and may be independently associated with changes in C_RS.

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