Comparing Clinical Features and Outcomes in Mechanically Ventilated Patients with COVID-19 and Acute Respiratory Distress Syndrome

Abstract

Rationale: Patients with severe coronavirus disease (COVID-19) meet clinical criteria for the acute respiratory distress syndrome (ARDS), yet early reports suggested they differ physiologically and clinically from patients with non–COVID-19 ARDS, prompting treatment recommendations that deviate from standard evidence-based practices for ARDS. Objectives: To compare respiratory physiology, clinical outcomes, and extrapulmonary clinical features of severe COVID-19 with non–COVID-19 ARDS. Methods: We performed a retrospective cohort study, comparing 130 consecutive mechanically ventilated patients with severe COVID-19 with 382 consecutive mechanically ventilated patients with non–COVID-19 ARDS. Initial respiratory physiology and 28-day outcomes were compared. Extrapulmonary manifestations (inflammation, extrapulmonary organ injury, and coagulation) were compared in an exploratory analysis. Results: Comparison of patients with COVID-19 and non–COVID-19 ARDS suggested small differences in respiratory compliance, ventilatory efficiency, and oxygenation. The 28-day mortality was 30% in patients with COVID-19 and 38% in patients with non–COVID-19 ARDS. In adjusted analysis, point estimates of differences in time to breathing unassisted at 28 days (adjusted subdistributional hazards ratio, 0.98 [95% confidence interval (CI), 0.77–1.26]) and 28-day mortality (risk ratio, 1.01 [95% CI, 0.72–1.42]) were small for COVID-19 versus non–COVID-19 ARDS, although the confidence intervals for these estimates include moderate differences. Patients with COVID-19 had lower neutrophil counts but did not differ in lymphocyte count or other measures of systemic inflammation. Conclusions: In this single-center cohort, we found no evidence for large differences between COVID-19 and non–COVID-19 ARDS. Many key clinical features of severe COVID-19 were similar to those of non–COVID-19 ARDS, including respiratory physiology and clinical outcomes, although our sample size precludes definitive conclusions. Further studies are needed to define COVID-19–specific pathophysiology before a deviation from evidence-based treatment practices can be recommended.

Fatal COVID-19 and Non–COVID-19 Acute Respiratory Distress Syndrome Is Associated with Incomplete Alveolar Type 1 Epithelial Cell Differentiation from the Transitional State without Fibrosis

“…Although initial studies suggested high mortality rates for COVID-19 ARDS 1 , recent evidence indicates that clinical outcomes of COVID-19 ARDS may be similar to those of ARDS from other etiologies 47 . Since the histology of COVID-19 ARDS is identical to that of ARDS of other etiologies [classic DAD ( Figures 1 A-D, Supplemental Figure S8) 26-28, 48 ], we hypothesized that the state of regeneration observed here is common to fatal early ARDS regardless of etiology.…”

Reply: Understanding COVID-19 Acute Respiratory Distress Syndrome: New Pathogen, Same Heterogeneous Syndrome

“…We found no significant difference in VRs between different ARDS groups: COVID-19 median (3,4). In fact, compared to VR estimates from a large cohort of non-COVID ARDS, nearly all values from our COVID-19 subjects (1.67 [1.49-2.24]) would have fallen within the second and third quartile (1.44-2.13) of a non-COVID ARDS distribution for VR (5).…”

“…We recognize that our cohort's small sample size limits statistical power to detect significant differences in VRs, if truly present. However, by contextualizing our results with the available comparative reports (3,4) and historic estimates of non-COVID ARDS VRs (5), COVID-19 is more similar than dissimilar from non-COVID ARDS in terms of dead-space ventilation.…”

Fatal COVID-19 and non-COVID-19 Acute Respiratory Distress Syndrome is Associated with Incomplete Alveolar Type 1 Epithelial Cell Differentiation from the Transitional State Without Fibrosis

“…Although initial studies suggested high mortality rates for COVID-19 ARDS 1 , recent evidence indicates that clinical outcomes of COVID-19 ARDS may be similar to those of ARDS from other etiologies 47 . Since the histology of COVID-19…”