JMIR Publications

ABSTRACT

Background:

Oxygen saturation is a crucial metric used for monitoring patients with lung disease or respiratory illness who are at risk of hypoxemia. Early and accurate identification of abnormal oxygen saturation is important for these patients who may develop significant desaturation and hypoxemia symptoms during their daily activities.

Objective:

This study aims to investigate the performance of two pulse oximeters, Masimo MightySat Rx finger pulse oximeter and Apple Watch Series 7, during a controlled oxygen desaturation protocol.

Methods:

We recruited nine healthy participants and performed a controlled oxygen desaturation study that reduces the blood oxygen saturation levels from 100% to 60% using a gas delivery system. We calculated the oxygen desaturation rate (ODR) of each measurement and conducted a comparative analysis of the displayed oxygen saturation readings of both the Masimo MightySat Rx finger pulse oximeter and Apple Watch Series 7 with arterial blood gas (ABG) readings obtained from the co-oximeter.

Results:

Both the Masimo MightySat Rx and the Apple Watch Series 7 tended to overestimate arterial oxygen saturation compared with ABG readings. The Masimo device demonstrated greater measurement agreement, with 49.03% of readings falling within the manufacturer’s ±2 % accuracy range, compared with 32.14% for the Apple Watch. Under low oxygen saturation conditions (< 88 %), the accuracy root mean square difference (Arms) was 3.52 [3.18–3.86]% for the Masimo MightySat Rx and 5.82 [5.32–6.31]% for the Apple Watch. Among the oxygen desaturation measurements with a desaturation rate larger than 2% SpO2 per minute, the Arms increased slightly by 1.10 % for the Masimo and 0.42 % for the Apple Watch. No statistically significant association was observed between desaturation rate and measurement error for either device.

Conclusions:

This study demonstrates that two pulse oximeters in our study overestimate oxygen saturation, particularly at lower oxygen saturation levels. The Masimo MightySat Rx provided more accurate measurements than the Apple Watch Series 7. Rapid Desaturation (ODR > 2% SpO2/min) did not significantly worsen accuracy in either device.