Silent hypoxemia – A specific sign of COVID-associated pneumonia?

Introduction. Pneumonia is a frequent manifestation of coronavirus infection. COVID-associated pneumonia is a disease characterized by a non-standard course and a number of clinical phenomena that complicate timely diagnosis and treatment.Aim. To investigate the phenomenon of mute hypoxemia in COVID-associated pneumonia.Materials and methods. The study included 214 patients who were divided into 2 groups. The study group included patients with confirmed COVID-associated pneumonia, and the control group included patients with interstitial lung diseases (idiopathic pulmonary fibrosis, nonspecific interstitial pneumonia, hypersensitivity pneumonitis). The subjective condition of the patient, presence of concomitant pathology, high-resolution computed tomography data, arterial blood gas composition, and spirometry data were evaluated.Results. In patients with COVID-associated pneumonia, “silent hypoxemia” was encountered 1.3 times more frequently than in patients with non-COVID-associated pneumonia. When comparing patients with silent hypoxemia and hypoxemia with dyspnea in COVID-associated pneumonia, statistically significantly higher values of PaCO2 and lower values of respiratory rate are observed. Such patterns are not detected in non-COVID-associated pneumonia. In patients with silent hypoxemia in non-COVID-associated pneumonia, the respiratory rate is statistically significantly higher compared to patients with COVID-associated pneumonia. Univariate logistic regression analysis demonstrates that in patients with non-COVID-associated pneumonia, silent hypoxemia is associated with BMI increase (OR = 1.380 (95% CI: 1.058–1.801); p = 0.017).Conclusion. The phenomenon of “silent hypoxemia” may manifest not only in pulmonary impairments resulting from SARS-CoV-2 infection but notably in COVID-associated pneumonia, where the absence of patient-reported dyspnea is substantiated by the lack of tachypnea. Owing to the subtleties of “silent hypoxemia”, clinical presentations may exhibit delays, diverting attention from significant pulmonary compromise, which could subsequently precipitate the failure of compensatory mechanisms.