The use of photoplethysmography for assessing hypertension

Abstract

The measurement of blood pressure (BP) is critical to the treatment and management of many medical conditions. High blood pressure is associated with many chronic disease conditions, and is a major source of mortality and morbidity around the world. For outpatient care as well as general health monitoring, there is great interest in being able to accurately and frequently measure BP outside of a clinical setting, using mobile or wearable devices. One possible solution is photoplethysmography (PPG), which is most commonly used in pulse oximetry in clinical settings for measuring oxygen saturation. PPG technology is becoming more readily available, inexpensive, convenient, and easily integrated into portable devices. Recent advances include the development of smartphones and wearable devices that collect pulse oximeter signals. In this article, we review (i) the state-of-the-art and the literature related to PPG signals collected by pulse oximeters, (ii) various theoretical approaches that have been adopted in PPG BP measurement studies, and (iii) the potential of PPG measurement devices as a wearable application. Past studies on changes in PPG signals and BP are highlighted, and the correlation between PPG signals and BP are discussed. We also review the combined use of features extracted from PPG and other physiological signals in estimating BP. Although the technology is not yet mature, it is anticipated that in the near future, accurate, continuous BP measurements may be available from mobile and wearable devices given their vast potential.

Photoplethysmography based atrial fibrillation detection: a review

“…One primary clinical application of PPG is arterial blood oxygen saturation (SpO2) estimation through pulse oximetry. 17 SpO2 is defined as the percentage of oxygen saturation in the arterial blood, which can be measured by the ratio of oxygenated hemoglobin concentration to the total hemoglobin concentration, with a normal range between 97% and 98%. 18 Recently, new applications of PPG have emerged for the continuous estimation of valuable cardiovascular parameters in ambulatory settings.…”

“…25 Additionally, some studies claim that arterial blood pressure could be estimated using advanced analysis of PPG. 17 Modes of PPG measurement A PPG signal has two main components: a quasi-static direct current (DC) component, which represents light reflected/transmitted from static arterial blood, venous blood, skin and tissues; and pulsatile alternate current (AC) component which arises from modulation in light absorption due to changes in arterial blood volume. PPG measurement can be carried out using two modes: transmission and reflectance.…”

Multimodal Photoplethysmography-Based Approaches for Improved Detection of Hypertension

“…The PWV is the speed at which a pressure wave travels down a segment of fixed length d and it can be calculated as PWV = d/PTT, where PTT is the pulse transit time. Based on the same idea, the pulse arrival time (PAT) is also tested and examined, and both PTT and PAT have been found to be closely correlated with BP [4]. The PTT and PAT durations reflect the time required for an arterial pressure wave to travel between a proximal and a distal site of an artery [5].…”

“…This has most commonly been measured using PPG as it has the ability to detect changes in blood pulsation through monitoring the variation in light absorption from a photodetector placed near a light-emitting diode [7]. Further details regarding the extraction of specific feature(s) from a single PPG signal and how these features can be incorporated into BP estimations are discussed and examined in our previous work [4,6,[8][9][10]. This review focuses on evaluating various PPG-based multimodal biosignal systems that have been investigated by researchers in an attempt to estimate BP and assess hypertension.…”

Neural Network-based Diabetic Type II High-Risk Prediction using Photoplethysmogram Waveform Analysis

“…Detecting of changes in blood volume in tissue microvascular bed can be achieved by PPG [10]. PPG's pulsatile components are related to blood volume changes inside arteries [11]. The well-known pulse oximeter is used to illuminate the skin (index finger, ear, or forehead) and then measure light absorption changes [12].…”