[Comparison between the first and second COVID-19 wave of patients who required invasive mechanical ventilation in an intensive care unit in Argentina].

Introduction: the information regarding characteristics and ventilatory results comparing the first (W1) and the second wave (W2) in Argentina are limited. The main objective of this study was to describe general characteristics and ventilatory variables in COVID-19 patients who required invasive mechanical ventilation (IMV) and compare differences between waves. Secondarily, factors associated with mortality in intensive care unit (ICU) were studied.

Methods: We conducted a prospective observational cohort study that included patients older than 18 years infected with SARS-CoV-2 consecutively admitted to ICU with IMV between August 1, 2020, and June 30, 2021. We included 412 patients.

Results: We found statistically significant differences (p < 0.001) in age [W1 64(55-72) vs W2 59 (50-66) years], presence of COPD [W1 n = 42 (19.8%) vs. W2 n = 13(6.3%)], plateau pressure [W1 27(25-30) cm H2O vsW2 24 (22-27) cmH2O], driving pressure (ΔP) [W1 15 (13-17) cmH2O vs. W2 12 (11-14) cm H2O] compliance [W1 40 mL/cmH2O (32-46) vs. W2 = 33 mL/cm H2O (27-40)]; reintubation [W1 30.4% (n = 63/207) vs. W2 13.7% (n = 28/205)]. We identified as independent factors associated with mortality the following variables: age [OR 1.07(95% CI 1.05-1.09)], the ΔP in the first 24 hours [OR 1.19(95% CI 1.10-1.28)] and W2 [OR 1.81 (95% IC1.12-2.93); p = 0.015.

Discussion: During W2 the patients were younger. It was possible to achieve ventilatory mechanics more adjusted to a protective ventilation strategy. In conclusion, in the patients studied, age and ΔP were independent predictors of mortality.