Photoplethysmography (PPG) makes uses of low-intensity infrared (IR) light. When light travels through biological tissues, it is absorbed by bones, skin pigments and both venous and arterial blood. However, as light is more strongly absorbed by blood than the surrounding tissues, the changes in blood flow can be detected by PPG sensors as changes in the intensity of light.~The signal from PPG is proportional to the quantity of blood flowing through the blood vessels and even small changes in blood volume can be detected using this method. Analysis of the waveform can provide information on a range of physiological measurements affecting the cardiovascular and respiratory systems. PPG is widely used in medicine in the form of pulse oximeters using sensors applied to peripheral digits.~Recently, it has been shown that PPG data can be obtained using images acquired from videos taken using the camera on smartphones and there is now a significant and growing body of published literature to support this.~DocMe Health Technologies has developed a system of obtaining these data using a video selfie.~At this time, the technology has been shown to be reasonably accurate when compared to home devices in healthy subjects. However, to make the technology more widely useful, the results obtained by video selfies need to be formally validated.~The aim of the study therefore is to compare measurements obtained from video selfies with measurements taken using already validated machines in the same patients.
The aim of this study is to compare accuracy of DocMe, a video technology developed by DocMe Health Technologies, with previously validated medical devices used for measurements of heart rate, heart rate variability, respiratory rate and blood pressure in adults.