COVID-19: Association of gasometric parameters at admission with in-hospital mortality

Introduction: At the beginning of the SARS-CoV-2 pandemic, acute respiratory failure has been the most important cause of hospitalization in patients with COVID-19, being more severe in patients with comorbidities and risk factors. In these scenarios hypoxemia has been associated with increased mortality. Our objective was to identify parameters obtained from arterial blood gases (ABG) associated with mortality in patients with COVID-19 at hospital admission. Methods: GSA samples obtained by breathing room air (FiO(2) 21%) processed in the clinical laboratory were retrospectively studied in an ABL90 flex analyzer (Radiometer). Results: Acute respiratory alkalosis was the predominant acid-base disturbance. Considering those patients with respiratory failure (paO(2) <60 mmHg), "silent" hypoxemia was observed in 11/176 (6%) of studied patients. In a multivariate analysis, three gasometric parameters at admission showed a positive association with hospital mortality: paO(2) (p=0.053), paO(2)/pO(2)e index (which expresses the paO(2) adjusted to the paO(2) expected for age) (p=0.047) and fractional saturation of hemoglobin (OxiHb%) (p=0.028). Discussion: GSA generate a key contribution in understanding the pathophysiology of the COVID-19 patient: in the initial evaluation, monitoring and prognosis of this disease.