Oxygen Saturation Measurement in Cyanotic Heart Disease with the Apple Watch

Background: Accurate measurement of transcutaneous oxygen saturation (tSO2) is of upmost importance for the assessment of cyanosis in congenital heart disease. Aim of this study was the evaluation of a supplementary tSO2 measurement with an Apple Watch in children with cyanotic heart disease.

Methods: During a 6-minute walk test (6MWT), measurement of tSO2 was performed simultaneously with an oximeter (Nellcor, Medtronic, United States) and an Apple Watch Series 7 (Apple inc, United States) in 36 children with cyanosis.

Results: Median age was 9.2 (IQR 5.7–13.8) years. tSO2 measurement with the Apple watch was possible in 35/36 and 34/36 subjects before and after 6MWT, respectively. Children, in whom Apple Watch measurement was not possible, had a tSO2 <85% on oximeter. Before 6MWT, median tSO2 was 93 (IQR 91–97%) measured by oximeter and 95 (IQR 93–96%) by the Apple watch. After a median walking distance of 437 (IQR 360–487) m, tSO2 dropped to 92 (IQR 88–95, (p < 0.001)) % by oximeter and to 94 (IQR 90–96, p = 0.013) % measured with the Apple Watch.

Conclusion: In children with mild cyanosis measurement of tSO2 with an Apple watch showed valid results if tSO2 was > 85%. In this setting, assessment of tSO2 at home could be helpful for patients and their families. In children with severe cyanosis < 85%, reliable tSO2 measurements with the Apple Watch were not possible.

Publication History

Article published online:
13 February 2024