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

Objective: A recent study investigated the potential utility of new photoplethysmogram (PPG) indicators to improve cuffless continuous blood pressure (BP) measurement. Approach: In this Comment we provide additional discussion of the physiology underlying PPG- and pulse arrival time (PAT)-based BP measurement. We also discuss validation of these measurements. Main results: Changes in PPG features and PAT can occur independently of BP. Any study validating BP measurement based on PPG features or PAT should include a variety of calibration independent physiological challenges affecting BP. Significance: PPG/PAT-based BP measurement has been investigated extensively as an alternative to cuff-based BP measurement. We feel the inherent physiological confounding in PPG/PAT-based measurement makes it unlikely that it will be of clinical value.