Reply to Comment on ‘New photoplethysmogram indicators for improving cuffless and continuous blood pressure estimation accuracy’

OBJECTIVE This article was written by the invitation of the editorial board of Physiological Measurement. It is a Reply to the Comment regarding our recently published paper entitled 'New photoplethysmogram indicators for improving cuffless and continuous blood pressure estimation accuracy' (Lin et al 2018 Physiol. Meas. 29 025005). APPROACH We appreciate van Helmond and Joseph's (2018 Physiol. Meas. 098001) interests and comments on our previous paper. In the Comment, they discussed in detail the physiology underlying the pulse arrive time (PAT)-based methods for blood pressure (BP) measurement, and concluded that there are inherent physiological reasons precluding the development of an accurate continuous cuffless BP measurement using PAT-based methods. We could agree with the comments of van Helmond and Joseph about the physiology underlying PAT-based methods for BP measurement. It may be difficult to minimize the confounding effects of physiological factors such as pre-ejection period and smooth muscle tone, etc. However, in this Reply, we discuss some potential solutions to deal with these problems from an engineering point of view. MAIN RESULTS When heart rate, more photoplethysmogram (PPG) features, PAT, robust machine learning models, and other techniques were adopted for BP estimation, it is promising for improving the accuracy of BP estimation to an acceptable range that can meet professional standards (e.g. Advancement of Medical Instrumentation (AAMI) standard, British Hypertension Society (BHS) protocol). SIGNIFICANCE PAT- and/or PPG-based methods may be a promising technique for continuous and unobtrusive blood pressure measurement.