Abstract
Background: Recent literature suggests respiratory system compliance (Crs) based phenotypes exist among COVID-19 ARDS patients. We sought to determine whether these phenotypes exist and whether Crs predicts mortality. Methods: A retrospective observational cohort study of 111 COVID-19 ARDS patients admitted March 11-July 8, 2020. Crs was averaged for the first 72-hours of mechanical ventilation. Crs<30ml/cmH2O was defined as poor Crs(phenotype-H) whereas Crs≥30ml/cmH2O as preserved Crs(phenotype-L). Results: 111 COVID-19 ARDS patients were included, 40 phenotype-H and 71 phenotype-L. Both the mean PaO2/FiO2 ratio for the first 72-hours of mechanical ventilation and the PaO2/FiO2 ratio hospital nadir were lower in phenotype-H than L(115[IQR87] vs 165[87], p=0.016), (63[32] vs 75[59], p=0.026). There were no difference in characteristics, diagnostic studies, or complications between groups. Twenty-seven (67.5%) phenotype-H patients died vs 37(52.1%) phenotype-L(p=0.115). Multivariable regression did not reveal a mortality difference between phenotypes; however, a 2-fold mortality increase was noted in Crs<20 vs >50ml/cmH2O when analyzing ordinal Crs groups. Moving up one group level (ex. Crs30-39.9ml/cmH2O to 40-49.9ml/cmH2O), was marginally associated with 14% lower risk of death(RR=0.86, 95%CI 0.72, 1.01, p=0.065). This attenuated (RR=0.94, 95%CI 0.80, 1.11) when adjusting for pH nadir and PaO2/FiO2 ratio nadir. Conclusion: We identified a spectrum of Crs in COVID-19 ARDS similar to Crs distribution in non-COVID-19 ARDS. While we identified increasing mortality as Crs decreased, there was no specific threshold marking significantly different mortality based on phenotype. We therefore would not define COVID-19 ARDS patients by phenotypes-H or L and would not stray from traditional ARDS ventilator management strategies.
Highlights
The coronavirus (COVID-19) pandemic was first reported in Wuhan, China in December 2019 and rapidly spread worldwide.[1,2] As of April 21st, 2021, there have been over 144 million cases globally, including 31 million cases and 569,000 deaths in the United States.[3]
A large percentage of COVID-19 patients who develop respiratory failure and hypoxemia have been diagnosed with acute respiratory distress syndrome (ARDS) and treated ; few data exist correlating respiratory pathophysiology to clinical features and ventilator mechanics in COVID-19
While some argue that the mechanical properties of COVID-19 affected lungs are unique, recent studies have shown that patients with COVID-19 ARDS versus non-COVID-19 ARDS are similar.[18,19,20,21]
Summary
The coronavirus (COVID-19) pandemic was first reported in Wuhan, China in December 2019 and rapidly spread worldwide.[1,2] As of April 21st, 2021, there have been over 144 million cases globally, including 31 million cases and 569,000 deaths in the United States.[3]. Mortality ranges from 30-60% among COVID-19 ICU patients and is even higher in patients requiring mechanical ventilation.[4,5,6,7,8,9]. A large percentage of COVID-19 patients who develop respiratory failure and hypoxemia have been diagnosed with acute respiratory distress syndrome (ARDS) and treated ; few data exist correlating respiratory pathophysiology to clinical features and ventilator mechanics in COVID-19. Several studies have demonstrated that some hypoxemic COVID-19 patients with respiratory failure requiring mechanical ventilation have higher than expected pulmonary compliance when compared to non-COVID-19 ARDS patients.[13,14,15]. Recent literature suggests respiratory system compliance (Crs) based phenotypes exist among COVID-19 ARDS patients. We sought to determine whether these phenotypes exist and whether Crs predicts mortality
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