Speckle Plethysmography Pulse Transit Time as a Marker of Blood Pressure Changes

Overview

Background: Blood pressure is one of the key markers of cardiovascular health. High blood pressure, also called hypertension, can increase the risk of heart disease or stroke. Monitoring a person s blood pressure continuously over a 24-hour period at home is the best way to diagnose hypertension, but the equipment currently used to do it is cumbersome. This natural history study will test a new technique for monitoring blood pressure continuously over time. Objective: To test a new technique (speckle plethysmography) for measuring blood pressure in healthy adults. Eligibility: Healthy people aged 18 years and older. Design: Participants will come to the clinic a minimum of 2 times. The screening visit will last up to 2 hours. Participants will have a physical exam. Their vital signs will be taken. The clinical visit will last up to 1 hour. Participants will recline in a chair. Sensors to measure the activity of the heart will be placed on their chest. Different sensors will be placed on two fingers and one big toe. A device to measure blood pressure will be placed on one arm. While wearing the sensors, participants will undergo 3 tests: They will be asked to breathe slowly for 2 minutes. They will be asked to solve a math problem. They will immerse one hand or foot into an ice bath for up to 2 minutes. Each test will be followed by a 5-minute recovery period. Participants may elect to return for up to 3 more visits during the following week.

Study Description: This pilot study will investigate the use of a recently introduced optical technique, speckle plethysmography (SPG), as an alternative to photoplethysmography (PPG) for cuff-free blood pressure (BP) estimation using pulse transit time (PTT). Because of the increased signal quality of SPG in comparison to PPG, we hypothesize that pulse transit times calculated from ECG-SPG (sPTT) will have a better correlation to blood pressure than ECG-PPG (pPTT). Objectives: Primary Objective: To examine the use of sPTT as a marker for blood pressure. Secondary Objective: To evaluate the use of sPTT in comparison to pPTT. Exploratory Objectives: 1. To explore if the SPG waveform by itself can be used as a marker for blood pressure. 2. To evaluate signal quality of SPG in comparison to PPG across various skin tones. Endpoints: Primary Endpoints: Pearson correlation coefficient between sPTT and BP. Secondary Endpoints: Pearson correlation coefficient between pPTT and BP. Exploratory Endpoints: 1. Pearson correlation coefficient between BP and signal markers to be determined. 2. PPG Signal-to-noise ratio (SNR), SPG SNR