Accuracy assessment of the LifePulsePro photoplethysmographic sensor for pulse interval measurement compared with reference electrocardiography

Photoplethysmography can be used for non invasive recording of pulse intervals and pulse rate variability, but interval based PPG measurements require validation against reference electrocardiography. This pilot technical study assessed the accuracy of the LifePulsePro photoplethysmographic sensor for measuring consecutive pulse intervals at rest compared with ECG RR intervals obtained using the BTL Flexi 12 ECG system and BTL CardioPoint software. Three subjects were examined, with two paired recordings analyzed for each subject. Recordings were performed at rest in the supine position. For each recording, the ECG RR interval series and the LifePulsePro pulse interval series were synchronized by interval order and compared after digital processing of the reference ECG data. The ECG correction constant used during reference interval processing was treated as a technical processing parameter and was not interpreted as pulse transit time or as a mean difference between ECG and LifePulsePro interval durations. Accuracy was assessed using mean absolute error, root mean square error, mean absolute percentage error, maximum absolute error, Pearson correlation, and Bland Altman analysis. A total of 139 matched intervals were analyzed across six paired recordings. After synchronization and correction, the mean absolute error ranged from 1.90 to 8.97 ms, and the mean absolute percentage error ranged from 0.20% to 1.03%. Pearson correlation ranged from 0.9726 to 0.9978, indicating strong preservation of beat to beat interval dynamics. The largest individual absolute difference was 25.35 ms. Bland Altman analysis showed a mean bias of 0.00 ms with 95% limits of agreement from −10.77 to +10.77 ms. These pilot data suggest that LifePulsePro can reproduce pulse interval sequences with good agreement compared with reference ECG under stable resting conditions. The device should be considered a tool for pulse interval recording and pulse rate variability assessment rather than a replacement for diagnostic ECG.