Validation of Apple Watch heart rate monitoring for patients under general anaesthesia (preprint)

Abstract: Background: The popularity and capabilities of wearable devices are increasing. We evaluated the accuracy of series III Apple Watch heart rate monitoring for patients under general anaesthesia.
Methods: Heart rate monitoring was performed on 5 patients (66.80 +/- 11.34 years) undergoing plastic/reconstructive surgery procedures. The Apple Watch heart rate records were compared with the heart provided by lead II electrocardiograph (1214 matched pairs) and differences assessed against the heart rate device accuracy criterion stipulated by the American National Standards Institute.
Results: The Apple Watch measurements were in close agreement with the electrocardiograph recordings with concordance correlation coefficient = 0.975). Only 3 of the 1214 Apple Watch records differed from the corresponding electrocardiograph heart rate by more than the American National Standards Institute criterion and the standard deviation of differences was 1.25bpm. The small average difference of 0.60 bpm is not clinically significant.
Conclusions: The results validate the series III Apple Watch as a reliable HR monitoring device for patients under general anaesthesia. This is supported by current literature. However, further investigation is required to determine the broader applications of the Apple Watch in anaesthesia.