Comparison of Pocket Pulse Oximeter and Standard Pulse Oximeter With ABG Analysis in Critically Ill Patients

Background: Pulse oximetry (SpO2) is a standard monitoring device in patients presenting to EMDs and intensive care units (ICUs). Pocket pulse oximeters (PPOs) are used widely in wards, EMDs, and small hospitals/clinics. These inexpensive PPOs also guide therapeutic interventions. Few studies have evaluated the accuracy of SpO2 in patients presenting to critical care areas vis-à-vis devices like PPO and standard pulse oximeter (SPO). This study becomes extremely relevant in view of the ongoing crisis of the COVID-19 pandemic wherein SpO2 monitoring is very important in hospitals, quarantine centers, small clinics, or even at home.  Methods: Patients presenting to critical areas who underwent arterial blood gases (ABG) analysis on the recommendation of the treating physician between November 2016 and October 2018 were included in this study. Along with the ABG analysis, a simultaneous assessment of SpO2 was done with a single PPO and SPO and all values were noted. Statistical analysis was done using the SPSS v.21.0 for Windows.  Results: The study included 300 patients. We compared the O2 saturations of ABG, SPO, and PPO with respect to sex, different age groups, and at different levels of ABG pCO2, HCO3, and pH in all patients. All parameters were compared using the Pearson’s correlation test; the results showed that ABG O2 saturations were closer to the SPO than the PPO but the differences were not statistically significant as the Pearson’s correlation values for all parameters were >0.8. We also compared the parameters by Bland Altman Plot and all observations were outside 95% CI (confidence interval), which means that there was a good agreement between O2 saturations by all three methods, that is, ABG, SPO, and PPO; however, ABG O2 saturations were closer to SPO than PPO but this difference was not statistically significant. Hence, we conclude that the PPO is a useful tool for reliable monitoring of O2 saturations.  Conclusion: This study highlights that inexpensive and noninvasive PPO can be used as a standard monitoring device with reliability in critically ill patients presenting to EMDs, ICUs, and small hospitals/clinics, quarantine centers, and even at home.