A systematic review and meta-analysis of respiratory system mechanics and outcomes in mechanically ventilated patients with COVID-19 related acute respiratory distress syndrome

ABSTRACT

Introduction: The respiratory mechanics, particularly static compliance of the respiratory system ( CRS) in COVID-19 acute respiratory distress syndrome (CARDS) is poorly understood. Whether or not distinct ARDS phenotypes based on CRS exist is still widely debated. Methods: We conducted a systematic review and meta-analysis, searching three international databases from 1st December 2019 to 15th July 2021 for studies reporting on the respiratory mechanics of patients with CARDS. The primary outcome was the CRS of both COVID-19 ARDS. Secondary outcomes included the mortality rates, lengths of stay, and ventilator free days. Random-effects (DerSimonian and Laird) meta-analyses were conducted. Results: 45 studies (13,334 patients) were included for analysis. The pooled CRS in patients mechanically ventilated for COVID-19 was 34.6 (95%-CI 33.4-35.8), and displayed a normal distribution (Shapiro- Wilk test p = 0.35). CRS was significantly associated with an PaO2/FiO2 ratio, positive end-expiratory pressure, and tidal volume;driving pressure was negatively associated with CRS. The pooled mortality rate was 36.2% (95%-CI 30.3-42.4%, ICU) and 38.9% (95%- CI 32.3-45.7%, 28-day). Conclusions: The respiratory mechanics of CARDS at the time closest to the initiation of invasive mechanical ventilation was normally distributed and did not reveal any distinct CRS- based phenotypes. However, to what extent the proposed unique pathophysiology of CARDS affects the current definition of ARDS and “exposes” its potential limitations remains a question for a high-quality, large prospective dataset to answer. Nonetheless, from our study-level analysis, CRS appears to be a heterogenous metric affected by both disease and intervention factors (Fig. 1) and physicians should treat patients with personalised and precise interventions in this context. (Table Presented).