Investigation of Optimal Light Source Wavelength for Cuffless Blood Pressure Estimation Using a Single Photoplethysmography Sensor

Abstract

Routine blood pressure measurement is important for the early detection of various diseases. Recently, cuffless blood pressure estimation methods that do not require cuff pressurization have attracted attention. In this study, we investigated the effect of the light source wavelength on the accuracy of blood pressure estimation using only two physiological indices that can be calculated with photoplethysmography alone, namely, heart rate and modified normalized pulse volume. Using a newly developed photoplethysmography sensor that can simultaneously measure photoplethysmograms at four wavelengths, we evaluated its estimation accuracy for systolic blood pressure, diastolic blood pressure, and mean arterial pressure against a standard cuff sphygmomanometer. Mental stress tasks were used to alter the blood pressure of 14 participants, and multiple linear regression analysis showed the best light sources to be near-infrared for systolic blood pressure and blue for both diastolic blood pressure and mean arterial pressure. The importance of the light source wavelength for the photoplethysmogram in cuffless blood pressure estimation was clarified.

Advances in Wearable Photoplethysmography Applications in Health Monitoring

“…In the current Special Issue, the optimization of hardware and software systems for a reliable PPG signal acquisition and pre-processing was one of the main topics. The influence of the light source wavelength of the PPG sensor on the accuracy of blood pressure estimation was investigated by Toda et al [ 5 ], who proposed a new system based on four light-emitting diodes (near-infrared (NIR), red, green, and blue) acquiring multi-wavelength PPG signals from the index finger. NIR was found to be the most accurate wavelength for the estimation of systolic blood pressure from PPG signals, and blue was the best performing when they extracted diastolic blood pressure and mean arterial pressure.…”