Association between ventilatory ratio and mortality in patients with acute respiratory distress syndrome and COVID 19: A multicenter, retrospective cohort study

BACKGROUND: Mortality rates in patients with COVID-19 undergoing mechanical ventilation in the intensive care unit are high. The causes of this mortality have been rigorously investigated. The aim of the present study is to establish mortality risk factors related to lung mechanics measured at days 1 and 5 in patients with covid-19 ARDS managed with invasive mechanical ventilation in the intensive care unit. METHODS: A retrospective observational multicenter study including consecutive patients with a confirmed diagnosis of COVID-19-induced ARDS, admitted to three institutions and seven intensive care units in the city of Bogota between May 20, 2020 and May 30, 2022 who required mechanical ventilation for at least five days. Data were collected from the medical records of patients who met the inclusion criteria on day 1 and day 5 of mechanical ventilation. The primary outcome assessed was mortality at day 30. RESULTS: A total of 533 consecutive patients admitted with ARDS with COVID-19 were included. Ventilatory ratio, plateau pressure and driving pressure measured on day 5 were significantly higher in non-survivors (p < 0.05). Overall, 30-day follow-up mortality was 48.8%. The increases between day 1 and day 5 in the ventilatory ratio (OR 1.42, 95%CI 1.03–2.01, p = 0.04), driving pressure (OR 1.56, 95%CI 1.10–2.22, p = 0.01); and finally plateau pressure (OR 1.9, 95%CI 1.34–2.69, p = 0.001) were associated with an increased risk of death. There was no association between deterioration of PaO(2)/F(I)O(2) index and mortality (OR 1.34, 95%CI 0.96–1.56, p = 0.053). CONCLUSIONS: Ventilatory ratio, plateau pressure, driving pressure, and age were identified as independent risk factors for 30-day mortality in patients with ARDS due to COVID-19 on day 5 of invasive mechanical ventilation.