Critical Care and Shock

Invasive mechanical ventilation during the first wave of COVID-19: Management and outcomes

Abstract

Objective: To describe demographics, clinical, and respiratory mechanics (including ventilatory management details) of patients admitted to the Intensive Care Unit (ICU) with severe COVID-19 and to evaluate the effectiveness of gas exchange variables, ventilatory parameters, and ICU illness severity scores in predicting 28-day mortality.

Design: Single-center retrospective cohort study.

Setting: Portuguese medical-surgical ICU.

Patients: Adults sequentially admitted to the ICU, from March 18 to May 12, 2020, with critical COVID-19 requiring invasive mechanical ventilation (IMV) for over 48 hours.

Interventions: None, due to study design.

Measurements and results: Data regarding positioning, positive end-expiratory pressure (PEEP), driving pressure, static lung compliance, and lowest daily arterial oxygen partial pressure to fractional inspired oxygen (PaO2/FiO2) ratio throughout the first 5 days of ICU admission were collected from daily ventilatory assessment charts. The median ICU length of stay was 11.3 days and median IMV duration was 9.5 days. The 28-day mortality was 12.1%. When comparing non-survivors and survivors, significant differences were found regarding Simplified Acute Physiology Score (SAPS) II (48.5, IQR 14.0 vs. 32.0, IQR 11.0, p=0.004), PaO2/FiO2 ratio before endotracheal intubation (101.3, IQR 22.5 vs. 174.1, IQR 9.5, p=0.01) and throughout ICU stay. Over 90% of patients were submitted to prone positioning. Use of low PEEP levels and maintenance of low driving pressures in patients whose overall compliance was low as possible.

Conclusions: Significant differences were found regarding SAPS II and PaO2/FiO2 ratios between survivors and non-survivors, eliciting further investigation as potential mortality predictors. With the second wave of the pandemic taking shape, sharing previous experience is crucial to further coordinate efforts internationally.