Validation of Polar Elixir™ Pulse Oximeter against Arterial Blood Gases during Stepwise Steady-State Inspired Hypoxia

Abstract

ABSTRACT Purpose The purpose of this study was to evaluate the accuracy of peripheral oxygen saturation (SpO2) measurements from Polar Elixir™ pulse oximetry technology compared with arterial oxygen saturation (SaO2) measurements during acute stepwise steady-state inspired hypoxia at rest. A post hoc objective was to determine if SpO2 measurements could be improved by recalibrating the Polar Elixir™ algorithm with SaO2 values from a random subset of participants. Methods The International Organization for Standardization (ISO) protocol (ISO 80601-2-61:2017) for evaluating the SpO2 accuracy of pulse oximeter equipment was followed whereby five plateaus of SaO2 between 70% and 100% were achieved using stepwise reductions in inspired O2 during supine rest. Blood samples drawn through a radial arterial catheter from 25 participants were first used to compare SaO2 with SpO2 measurements from Polar Elixir™. Then the Polar Elixir™ algorithm was recalibrated using SaO2 data from 13 random participants, and SpO2 estimates were recalculated for the other 12 participants. For SaO2 values between 70% and 100%, root mean square error, intraclass correlation coefficients (ICC), Pearson correlations, and Bland–Altman plots were used to assess the accuracy, agreement, and strength of relationship between SaO2 values and SpO2 values from Polar Elixir™. Results The initial root mean square error for Polar Elixir™ was 4.13%. After recalibrating the algorithm, the RMSE was improved to 2.67%. The ICC revealed excellent levels of agreement between SaO2 and Polar Elixir™ SpO2 values both before (ICC(1,3) = 0.837, df = 574, P < 0.001) and after (ICC(1,3) = 0.942, df = 287, P < 0.001) recalibration. Conclusions Relative to ISO standards, Polar Elixir™ yielded accurate SpO2 measurements during stepwise inspired hypoxia at rest when compared with SaO2 values, which were improved by recalibrating the algorithm using a subset of the SaO2 data.