Evaluation of the predictors and frequency of silent hypoxemia in COVID-19 patients and the gap between pulse oximeter and arterial blood gas levels: A cross-sectional study

Abstract

Background

Silent hypoxemia is when patients do not experience breathing difficulty in the presence of alarmingly low O₂ saturation. It could cause rapid deterioration and higher mortality rates among patients, so prompt detection and identifying predictive factors could result in significantly better outcomes. This study aims to document the evidence of silent hypoxemia in patients with COVID-19 and its clinical features.

Methods

A total of 78 hospitalized, nonintubated patients with confirmed COVID-19 infection were included in this study. Their O₂ saturation was measured with a pulse oximeter (PO), and arterial blood gas (ABG) was taken. Demographic and clinical features were recorded. The Borg scale was used to evaluate dyspnea status, and patients with a score of less than two accompanied by O₂ saturation of less than 94% were labeled as silent hypoxic. Univariate analysis was utilized to evaluate the correlation between variables and their odds ratio (OR) and 95% confidence interval (CI).

Results

Silent hypoxemia was observed in 20 (25.6%) of the participants. The average difference between the PO and ABG methods was 4.36 ± 3.43. Based on regression analysis, dyspnea and respiratory rate demonstrated a statistically significant correlation with the O₂ saturation difference between PO and ABG (OR: 2.05; p = 0.026; 95% CI: 0.248–3.847 and OR: 0.144; p = 0.048, 95% CI: 0.001–0.286). Furthermore, the Borg scale (OR: 0.29; p = 0.009; 95% CI: 0.116–0.740) had a significant reverse correlation with silent hypoxia.

Conclusions

Silent hypoxemia can be a possible complication that affects some COVID-19 patients. Further care should be bestowed upon the younger population and those with underlying neurological or mental illnesses. Furthermore, the respiratory rate, pulse oximeter, and arterial blood gas O₂ levels should be considered alongside each other.