Comparison of Arterial Oxygen Saturation Measured by Pulse Oximetry at Different Sensor Sites in Neurocritical Patients

Purpose : This study aimed to compare peripheral pulse oxygen saturation (SpO2) values, measured at different monitoring sites, and arterial oxygen saturation (SaO2) of neurocritical patients.Methods : The study included 110 patients admitted to the neurosurgical intensive care unit of a university hospital. The patients’ SpO2 values were measured in their index fingers, both second toes, both earlobes, and foreheads, using the patient monitoring system. These values were compared with the standard value of SaO2 measured using a blood gas analyzer. Data were analyzed using descriptive values, Pearson’s correlation coefficients, Lin’s concordance correlation coefficients (CCC), and Bland-Altman plots.Result : Regardless of the measuring site, SpO2 was correlated with the paired measurements of SaO2 (r=.40~.60, p＜.001, CCC range=.40~.58). No significant bias in paired measurements of SpO2 and SaO2 was observed at all sites (-0.06~0.19%, p＞.05). SpO2 values at the left finger and right earlobe had the narrowest range, with a 95% limits of agreement (LOA) (left finger -3.04~2.93% and right earlobe -3.18~2.79%). SpO2 at the index finger, on the side without an arterial catheter, had a narrower range of 95% LOA than that of the opposing finger (-3.00~2.97% vs. -3.73~3.26%).Conclusion : SpO2 at the finger without an arterial catheter had the highest level of precision. This study suggests using the index finger, on the side without an arterial catheter, for pulse oximetry in neurocritical patients.