RESUMEN
Background: Coronavirus disease 2019 (COVID-19) has been frequently complicated by severe acute respiratory distress syndrome (ARDS) with prolonged invasive ventilation. While respiratory system compliance and lung recruitability have been described within the first days after ICU admission, data about their longitudinal changes are still limited. Therefore, we conducted this study to assess the evolution of respiratory system compliance and lung recruitability in patients with COVID-19-related ARDS. Method: We conducted a prospective single-center study in patients admitted for COVID-19-related ARDS during the first wave of the pandemic, from March 16, 2020 to April 10, 2020. Respiratory system compliance was calculated daily at clinical positive end-expiratory pressure (PEEP) during passive breathing. The potential for lung recruitment was assessed by measuring the volume derecruited between PEEP 15 cmH2O and 5 cmH2O, and using the calculation of the recruitment-to-inflation ratio (R/I ratio). Recruitable lung was considered when the R/I ratio was at least 0.5. The primary outcome was the evolution of respiratory mechanics over time. The secondary outcome was the evolution of lung recruitability over time. Results: Thirty-two patients were included in this study. The respiratory mechanics were assessed 222 times (7 ± 5 times per patient). Respiratory system compliance at clinical PEEP was 29.1 mL/cmH2O (interquartile range [IQR]: 24.1-33.9 mL/cmH2O) and decreased significantly over time (P <0.0001). Lung recruitability was assessed in 22 out of the 32 patients (60 assessments). The median volume derecruited between PEEP 15 cmH2O and 5 cmH2O was 246.8 mL (IQR: 180.8-352.2 mL) and the median R/I ratio was 0.56 (IQR: 0.39-0.73). Neither changed significantly over time. The proportion of patients with recruitable lung was 50.0% (6/12) within the first 3 days after intubation, 69.2% (9/13) between day 4 and day 7, and 66.7% (8/12) after day 7 (P=0.7934). Conclusions: In our cohort, respiratory system compliance was low and decreased over time. The potential for lung recruitment was high and persisted despite prolonged mechanical ventilation, suggesting that maintaining high PEEP levels in the later course of COVID-19 could be adequate.
RESUMEN
In intensive care units (ICUs), the decision to extubate is a critical one because mortality is particularly high in case of reintubation. Around 15% of patients ready to be weaned off a ventilator experience extubation failure leading to reintubation. The use of high-flow nasal oxygen and non-invasive ventilation are two alternatives of standard oxygen supplementation that may help to prevent reintubation. High-flow nasal oxygen and non-invasive ventilation, may be used to prevent reintubation in patients with low (e.g., patients without comorbidities and with short durations of mechanical ventilation) and high risk (e.g., patients >65 years and those with underlying cardiac disease, chronic respiratory disorders, and/or hypercapnia at the time of extubation) of reintubation, respectively. However, non-invasive ventilation used as a rescue therapy to treat established post-extubation respiratory failure could increase mortality by delaying reintubation, and should therefore be used very carefully in this setting. The oxygenation strategy to be applied in postoperative patients is different from the patients who are extubated in the ICUs. Standard oxygen after a surgical procedure is adequate, even following major abdominal or cardiothoracic surgery, but should probably be switched to high-flow nasal oxygen in patients with hypoxemic. Unlike in patients experiencing post-extubation respiratory failure in ICUs wherein non-invasive ventilation may have deleterious effects, it may actually improve the outcomes in postoperative patients with respiratory failure. This review discusses the different clinical situations with the aim of choosing the most effective oxygenation strategy to prevent post-extubation respiratory failure and to avoid reintubation.