Impacto de um protocolo de ajuste da fração inspirada de oxigênio na frequência de hiperoxemia e uso excessivo de oxigênio em pacientes em ventilação mecânica por covid-19

Abstract

Introduction: Patients with severe forms of pneumonia caused by coronavirus (COVID19) can meet criteria for acute respiratory distress syndrome and may require invasive mechanical ventilation with high fraction of inspired oxygen (FiO2) to reverse hypoxemia. The exposure to high FiO2 (excessive oxygen level) and elevated levels of oxygen in plasma (hyperoxemia) can be associated with worse outcomes. Than, a more conservative oxygen use controlled by peripheral oxygen saturation can reduce risks and spare oxygen. Objective: We examined weather a protocol for FiO2 adjustment can reduce hyperoxemia and excess oxygen use in COVID-19 patients mechanically ventilated. Methods: A prospective comparative cohort study conducted in two intensive care units (ICU) dedicated to COVID-10 patients in mechanical ventilation. A FiO2 adjustment protocol was already applied in one of the participant ICU (conservative-oxygen ICU) and the other, did not follow the FiO2 protocol (control-ICU). Consecutive patients aged 18 years or older, admitted in the ICUs with COVID-19 and who received invasive mechanical ventilation were eligible. We excluded patients who had received invasive mechanical ventilation for more than 24 hours before admission, patients who were ventilated for less than 48 hours, patients with hypoxemia on day 0, and those for whom life-sustaining treatment was withheld. The ventilatory parameters were set to keeping a protective mechanical ventilation. At ICU admission, clinical and laboratory data day 1 (D1) and day (2). Hyperoxemia was defined as PaO2 >100 mmHg and excess oxygen use as FiO2 >60% in patients with hyperoxemia. Sustained hyperoxemia was defined as the presence of hyperoxemia on days 1 and 2. Secondary outcomes included: occurrence of hypoxemia (PaO2 < 55 mmHg, regardless of FiO2), number of ventilator-free days at day 28, length of stay in the ICU, ICU mortality, hospital mortality in 28 and 60 days Results: Eighty-two patients from the conservative-oxygen ICU and 145 from the control ICU were included. The conservative-oxygen ICU presented lower prevalence of hyperoxemia on day 1 (40.2% vs. 75.9%, p < 0.001) and day 2 (32.9% vs. 65.5%, p< 0.001) and of sustained hyperoxemia (12.2% vs. 49.6%, p < 0.001). Excess oxygen use was less frequent in the conservative-oxygen ICU on day 1 (18.3% vs. 52.4%, p < 0.001) and day 2 (10.9% vs. 35.2%, p , p <0 .001). Being admitted in the control ICU was independently associated with hyperoxemia (OR = 9.04, IC95% (3.94-20.73), p <0.0001 1), sustained hyperoxemia (OR = 6.73, IC95% (2.98-15.19), p <0.0001) and excess oxygen use (OR = 4.85, IC95% (2.44-9.61), p <0.001 Multivariable analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FiO2 use and adverse clinical outcomes. Conclusions: Following FiO2 protocol was associated with lower hyperoxemia and less excess oxygen use. Although those results were not associated with better clinical outcomes, adopting FiO2 protocol may be useful in a scenario of depleted oxygen resources, as was seen during the COVID-19 pandemic.