Early Improvement of Acute Respiratory Distress Syndrome in Patients With COVID-19 in the Intensive Care Unit: Retrospective Analysis

Abstract

Background: Since the start of the COVID-19 pandemic, there have been over 2 million deaths globally. Acute respiratory distress syndrome (ARDS) may be the main cause of death.

Objective: This study aimed to describe the clinical features, outcomes, and ARDS characteristics of patients with COVID-19 admitted to the intensive care unit (ICU) in Chongqing, China.

Methods: The epidemiology of COVID-19 from January 21, 2020, to March 15, 2020, in Chongqing, China, was analyzed retrospectively, and 75 ICU patients from two hospitals were included in this study. On day 1, 56 patients with ARDS were selected for subgroup analysis, and a modified Poisson regression was performed to identify predictors for the early improvement of ARDS (eiARDS).

Results: Chongqing reported a 5.3% case fatality rate for the 75 ICU patients. The median age of these patients was 57 (IQR 25-75) years, and no bias was present in the sex ratio. A total of 93% (n=70) of patients developed ARDS during ICU stay, and more than half had moderate ARDS. However, most patients (n=41, 55%) underwent high-flow nasal cannula oxygen therapy, but not mechanical ventilation. Nearly one-third of patients with ARDS improved (arterial blood oxygen partial pressure/oxygen concentration >300 mm Hg) in 1 week, which was defined as eiARDS. Patients with eiARDS had a higher survival rate and a shorter length of ICU stay than those without eiARDS. Age (<55 years) was the only variable independently associated with eiARDS, with a risk ratio of 2.67 (95% CI 1.17-6.08).

Conclusions: A new subphenotype of ARDS-eiARDS-in patients with COVID-19 was identified. As clinical outcomes differ, the stratified management of patients based on eiARDS or age is highly recommended.

Keywords: ARDS; COVID-19; Chongqing; acute respiratory distress syndrome; characteristic; critically ill; epidemiology; improvement; intensive care unit; mortality; outcome.

Figure 1

Comparison of patients with and without early improvement of acute respiratory distress syndrome (eiARDS). (A) All patients with ARDS on day 1, divided into two groups (eiARDS and non-eiARDS) according to PaO₂/FiO₂ on day 7. (B) No significant difference between the two groups in the PaO₂/FiO₂ on day 1. (C) No significant difference between the two groups in the proportion of pneumonia volume on day 1. (D) The length of intensive care unit stay exhibited differences between the two groups.