OBJECTIVE Peak plantar pressures (PPPs) have been studied extensively as a contributing factor to skin breakdown, especially in the forefoot where most plantar neuropathic ulcers occur. The purposes of this article were to 1) describe an additional pressure variable, the peak pressure gradient (PPG), 2) determine whether the PPG is higher in the forefoot than in the rearfoot (even when compared...

Pulse transit time, which correlates with blood pressure, is measured between the electrocardiogram R-wave peak and 50% raising front level of a photoplethysmographic (PPG) signal. Registered PPG signal bandwidth may be shared by noise and therefore the signal raising front is undetectable. Electrocardiogram reference adaptive sum comb filter was used to extract the harmonic components of the P...

The purpose of this paper is twofold. The first purpose is to detect M-peaks from raw photoplethysmography (PPG) signals with no preprocessing method applied to the signals. The second purpose is to estimate heart rate variability (HRV) by finding the peaks in the PPG signal. HRV is a measure of the fluctuation of the time interval between heartbeats and is calculated based on time series betwe...

Recent clinical studies show that the contour of the photoplethysmogram (PPG) wave contains valuable information for characterizing cardiovascular activity. However, analyzing the PPG wave contour is difficult; therefore, researchers have applied first or higher order derivatives to emphasize and conveniently quantify subtle changes in the filtered PPG contour. Our hypothesis is that analyzing ...

Pulse oximetry is based on the technique of photoplethysmography (PPG) wherein light transmitted through tissues is modulated by the pulse. In addition to variations in light modulation by the cardiac cycle, the PPG signal contains a respiratory modulation and variations associated with changing tissue blood volume of other origins. Cardiovascular, respiratory, and neural fluctuations in the PP...

Photoplethysmography (PPG) is used to estimate the skin blood flow using infrared light. Researchers from different domains of science have become increasingly interested in PPG because of its advantages as non-invasive, inexpensive, and convenient diagnostic tool. Traditionally, it measures the oxygen saturation, blood pressure, cardiac output, and for assessing autonomic functions. Moreover, ...

The study aimed to explore the regulatory effect of endogenous hydrogen sulfide (H(2)S), a novel gasotransmitter, on pulmonary vascular structure and gasotransmitters in rats with high pulmonary blood flow. Thirty-two Sprague-Dawley rats were randomly divided into a sham group, shunt group, sham+PPG (propargylglycine, an inhibitor of cystathionine-gamma-lyase) group and shunt+PPG group. Rats in...

Abstract: The measurement accuracy for heart rate or SpO2 using photoplethysmography (PPG) is influenced by how well the noise from motion artifacts and other sources can be removed. Eliminating the motion artifacts is particularly difficult since its frequency band overlaps that of the basic PPG signal. Therefore, we propose the Periodic Moving Average Filter (PMAF) to remove motion artifacts....

Photoplethysmographic (PPG) signals are easily corrupted by motion artifacts when the subjects perform physical exercise. This paper introduces a two-step processing scheme to estimate heart rate (HR) from wrist-type PPG signals strongly corrupted by motion artifacts. Adaptive noise cancellation, using normalized least-mean-square algorithm, is first performed to attenuate motion artifacts and ...

To study the fate of L-cysteine and amino acid homeostasis in liver after the inhibition of the trans-sulfuration pathway, rats were treated with propargylglycine (PPG). At 4 h after the administration of PPG, liver cystathionase (EC 4.4.1.1) activity was undetectable, L-cystathionine levels were significantly higher, L-cysteine was unchanged and GSH concentration was significantly lower than v...