Comparison of Peripheral Blood Oxygen Saturation Measurements Using Pulse Oximetry at Three Anatomical Sites on Sleep Patients

Abstract

ABSTRACTBackground and ObjectiveAccurate measurements of peripheral blood oxygen saturation (SpO2) are important in evaluating sleep patients with frequent desaturations due to pathological breathing events. This project compared synchronised SpO2 measurements at the finger, forehead and toe of patients undergoing Type 1 polysomnography (PSG) to evaluate potential SpO2 variability across the sites.MethodsPulse oximetry SpO2 measurements were simultaneously and continuously recorded for 41 sleep patients at the finger, forehead and toe, and synchronised with PSG data. Recordings were scored for desaturations of ≤ 3% (peak to trough, lasting ≤10 seconds), signal dropouts, and artefact occurrences. Forehead and toe SpO2 measurements were compared against the finger as the standard PSG oximetry site.ResultsDifferences between anatomical sites for mean SpO2, mean number of SpO2 desaturations per hour, and time spent below an SpO2 level of 95% during total sleep time were significant (P < 0.01). The forehead pulse oximeter had the highest mean SpO2, least number of SpO2 desaturations per hour, and experienced the least number of artefact occurrences. Dropouts were lowest for the forehead and toe pulse oximeters.ConclusionDifferences between SpO2 measurements, dropouts and artefact occurrences at the finger, forehead and toe may have diagnostic and prognostic implications for sleep patients. The differences in SpO2 measurements may be attributed to variability in perfusion of the extremities and core during sudden oscillating blood pressure changes associated with breathing events. Further research is required to determine which anatomical site correlates closest to arterial oxygenation for pulse oximetry in sleep patients.BRIEF SUMMARYStudy rationaleAn absence of research investigating anatomical site location for pulse oximetry during overnight polysomnography exists. Our study was performed to fill this gap, as accurate pulse oximetry measurements are key for the diagnosis, treatment and monitoring of sleep patients; a patient cohort where SpO2 desaturations are recurrent.Study impactOur findings demonstrate there are significant differences between finger, forehead and toe pulse oximetry measurements, particularly SpO2 desaturations per hour, which may have diagnostic and clinical implications. This research is applicable and important to not only sleep physicians and scientists, but also other disciplines where continuous SpO2 monitoring is required.