A Correlation Analysis of Peripheral Oxygen Saturation and Arterial Oxygen Saturation Among COVID-19 Patients.

ABSTRACT

Background and objective It has been observed that peripheral oxygen saturation (SpO2) measured by pulse oximeter is consistently lower than arterial oxygen saturation (SaO2) measured directly by blood gas analysis. In this study, we aimed to evaluate the correlation between SpO2 and SaO2, and SpO2 and partial pressure of oxygen (PaO2), and compare the SpO2/FiO2 (SF) and PaO2/FiO2 (PF) ratios in patients with coronavirus disease 2019 (COVID-19). Methods In this observational study, SpO2 was recorded and arterial blood gas analysis was performed among 70 COVID-19 patients presenting on room air (FiO2 = 0.21). SaO2 and PaO2 were recorded from arterial blood gas analysis. The SF and PF ratios were then calculated. Results The strength of correlations between SpO2 and SaO2, and SpO2 and PaO2, were significant (p<0.001) and moderately positive [Pearson coefficient (r) = 0.68, 0.53]. SpO2 value (85%), i.e., SF ratio (404.7 or below), was the best estimate for mild ARDS (acute respiratory distress syndrome) [PF ratio (300 or below)] with a sensitivity of 80.6% and specificity of 53%. Conclusion A pulse oximeter is a vital tool in the diagnosis and management of COVID-19. In our study, SpO2 was found to have a positive correlation with SaO2 and PaO2 with acceptable sensitivity but low specificity in estimating mild ARDS. Therefore, pulse oximetry can be used as a tool for the early diagnosis of mild COVID-19 ARDS as per the given considerations and clinical correlation.