Extraction of Heart Rate Variability from Smartphone Photoplethysmograms

Abstract

Heart rate variability (HRV) is a useful clinical tool for autonomic function assessment and cardiovascular diseases diagnosis. It is traditionally calculated from a dedicated medical electrocardiograph (ECG). In this paper, we demonstrate that HRV can also be extracted from photoplethysmograms (PPG) obtained by the camera of a smartphone. Sixteen HRV parameters, including time-domain, frequency-domain, and nonlinear parameters, were calculated from PPG captured by a smartphone for 30 healthy subjects and were compared with those derived from ECG. The statistical results showed that 14 parameters (AVNN, SDNN, CV, RMSSD, SDSD, TP, VLF, LF, HF, LF/HF, nLF, nHF, SD1, and SD2) from PPG were highly correlated (r > 0.7, P < 0.001) with those from ECG, and 7 parameters (AVNN, TP, VLF, LF, HF, nLF, and nHF) from PPG were in good agreement with those from ECG within the acceptable limits. In addition, five different algorithms to detect the characteristic points of PPG wave were also investigated: peak point (PP), valley point (VP), maximum first derivative (M1D), maximum second derivative (M2D), and tangent intersection (TI). The results showed that M2D and TI algorithms had the best performance. These results suggest that the smartphone might be used for HRV measurement.

Analysis of a Pulse Rate Variability Measurement Using a Smartphone Camera

“…All these requirements can be satisfied using a widely accessible tool called a smartphone like an iPhone 6. There were similar developments in the past, using other types of smartphones [12, 13, 20], but the device and implementation only permitted a low-frequency PPG measurement. The PPG measurement was compared to ECG statistics in that literature, and there was found to be a good correspondence between the HRV (heart rate variability) and PRV parameters.…”

“…The iPhone 6 smartphone supports a 240-frame-per-second (FPS) video recording, the so-called “Slow-mo” video, and based on this feature, our plan was to develop a PPG measurement application with a sampling rate of 240 Hz. Another goal of this study was to compare our PRV measurements with those HRV parameters computed from the gold standard ECG signals and also to investigate our comparison results among other experiment results like those of [12, 13, 21]. Because different comparison methodologies were used in different research studies, we collected many of the HRV feature computation and comparison methods for the purpose of a thorough investigation.…”

“…ECG is a voltage signal, while PPG is the time serial got from digitalizing the measurements of the reflected or absorbed light, which changes with the periodic blood flow. PRV can be easily measured with the help of a smartphone flash and camera [12, 13] (or using other low-cost tools [14]). The operation of PPG is well formulated by the authors of [15]: “PPG is measured via reflection through the illumination of the skin using an LED (e.g., the smartphone's flash) and through the detection of the amount of light that is reflected by a photodetector or a camera located next to the light source.…”

Real Time Telemedical Health Care Systems with Wearable Sensors

“…11 A new technique has also been practiced as replacement for traditionally calculated HVR from dedicated medical Electrocardiograph (ECG) 2 . It offers low-cost, ease-of-use in and outside the hospital.…”

National instruments labVIEW and video imaging technique for health status monitoring

“…2017, 9(3S), 858-886 860 muscle through the electrodes placing on specific human anatomical i.e. chests, legs, and arms [11]. Usually ECG test services only provided in certain health facilities because ECG machines are extremely bulky and expensive [12][13].…”