Accuracy of smartwatches for measuring heart rate and oxygen saturation in cynomolgus macaques compared to clinical standards

Continuous monitoring of physiological parameters in non-human primates (NHPs) necessitates a precise, non-invasive, and convenient method. This study aimed to validate the use of smartwatches with integrated pulse oximetry and heart rate (HR) monitoring capabilities for use in NHPs. Currently, the clinical standard for non-invasive continuous monitoring of peripheral oxygen saturation (SpO₂) in NHPs has been the use of a transmittance pulse oximeter (TPO) affixed to a location of highly vascularized tissue. In a clinical setting, HR is monitored through electrocardiogram (ECG) or associated with SpO₂ measurement from a TPO probe utilizing photoplethysmography technology. Challenges in obtaining precise readings with TPOs stem from technological limitations and probe placement restrictions. To address these limitations, simultaneous HR and SpO₂ measurements were obtained from 15 cynomolgus macaques (<i>Macaca fascicularis</i>) using the Apple Watch 7 (AW 7), Apple Watch 9 (AW 9), and a clinical-grade TPO probe with integrated optical HR measurement technology (iM70, ELAN). Arterial blood gas (ABG) analysis was used as a reference method for SpO₂. We found that a TPO device significantly underestimated SpO₂ compared to the AW 7 and AW 9 when referenced against ABG values. Smartwatch-derived HR and SpO₂ measurements demonstrated good agreement and minimal bias compared to the gold standard method. Overall, the AW 7 and AW 9 exhibited good agreement with clinical reference standards for HR and good agreement with the gold standard for SaO₂ in sedated cynomolgus macaques.