Ambient temperature effect on pulse rate variability as an alternative to heart rate variability in young adult

Abstract

Pulse rate variability (PRV) is a promising physiological and analytic technique used as a substitute for heart rate variability (HRV). PRV is measured by pulse wave from various devices including mobile and wearable devices but HRV is only measured by an electrocardiogram (ECG). The purpose of this study was to evaluate PRV and HRV at various ambient temperatures and elaborate on the interchangeability of PRV and HRV. Twenty-eight healthy young subjects were enrolled in the experiment. We prepared temperature-controlled rooms and recorded the ECG and photoplethysmography (PPG) under temperature-controlled, constant humidity conditions. The rooms were kept at 17, 25, and 38 °C as low, moderate, and high ambient temperature environments, respectively. HRV and PRV were derived from the synchronized ECG and PPG measures and they were studied in time and frequency domain analysis for PRV/HRV ratio and pulse transit time (PTT). Similarity and differences between HRV and PRV were determined by a statistical analysis. PRV/HRV ratio analysis revealed that there was a significant difference between HRV and PRV for a given ambient temperature; this was with short-term variability measures such as SDNN SDSD or RMSSD, and HF-based variables including HF, LF/HF and normalized HF. In our analysis the absolute value of PTT was not significantly influenced by temperature. Standard deviation of PTT, however, showed significant difference not only between low and moderate temperatures but also between low and high temperatures. Our results suggest that ambient temperature induces a significant difference in PRV compared to HRV and that the difference becomes greater at a higher ambient temperature.

Can Wearable Devices Accurately Measure Heart Rate Variability? A Systematic Review

“…Finger tips have also been used as a measuring site but only in stationary conditions: it has been shown that HRV derived from fi ngertip PPG had an excellent correlation to ECG in stationary conditions. 38 However, a comparative study of fi nger derived PRV and HRV in healthy subjects 40 using a stationary equipment found a poor correlation and suggested that fi nger derived PRV might not be suitable to substitute ECG derived HRV, as has been mentioned by other authors, too 41 .…”

“…Also, the term 'pulse rate variability' (PRV), which is derived from PPG, has been suggested as a potential analog of HRV. 37,38 As PRV is further processed identically to HRV, the derived parameters can be extracted from both methods such as the standard deviation of normal to normal (SDNN) R-R intervals (NN), root mean square of successive differences between adjacent NN intervals (RMSSD), proportion of NN50 in total NN intervals (pNN50), low frequency (LF) power, high frequency (HF) power and LF/ HF ratio (LF/HF).…”

“…This study concluded that ambient temperature could induce a difference in the short-term variables that refl ect the parasympathetic activity between HRV and PRV. 38 4. Software analysis: Some proprietary software systems for collection and analysis of RV data exist like the PPT5 or the Ithlete TM software application 14,26,27 or freely available software may be used e.g.…”

Evaluation of Coherence Between ECG and PPG Derived Parameters on Heart Rate Variability and Respiration in Healthy Volunteers With/Without Controlled Breathing

“…Each signal was resampled to 250 Hz then to be analyzed by a personal computer. On account of a significant difference between HRV and PRV at higher ambient temperatures [20], all recordings were performed in a bright and quiet room with a constant temperature of 24-25 °C.…”

“…Figure 3 shows an example of the recurrence plot. When given two time series of x(i) and y(i), a recurrence plot is a representation of the normalized distance between the points (x(i), y(i)) and (x(j), y(j)), plotted in the time-to-time domain [19,20].…”