Frequency spectrum analysis of finger photoplethysmographic waveform variability during haemodialysis

Abstract

This study investigates the peripheral circulatory and autonomic response to volume withdrawal in haemodialysis based on spectral analysis of photoplethysmographic waveform variability (PPGV). Frequency spectrum analysis was performed on the baseline and pulse amplitude variabilities of the finger infrared photoplethysmographic (PPG) waveform and on heart rate variability extracted from the ECG signal collected from 18 kidney failure patients undergoing haemodialysis. Spectral powers were calculated from the low frequency (LF, 0.04-0.145 Hz) and high frequency (HF, 0.145-0.45 Hz) bands. In eight stable fluid overloaded patients (fluid removal of >2 L) not on alpha blockers, progressive reduction in relative blood volume during haemodialysis resulted in significant increase in LF and HF powers of PPG baseline and amplitude variability (P < 0.01), when expressed in mean-scaled units. The augmentation of LF powers in PPGV during haemodialysis may indicate the recovery and possibly further enhancement of peripheral sympathetic vascular modulation subsequent to volume unloading, whilst the increase in respiratory HF power in PPGV is most likely a sign of preload reduction. Spectral analysis of finger PPGV may provide valuable information on the autonomic vascular response to blood volume reduction in haemodialysis, and can be potentially utilized as a non-invasive tool for assessing peripheral circulatory control during routine dialysis procedure.

Fingertip photoplethysmographic waveform variability and systemic vascular resistance in intensive care unit patients

“…While previous studies have demonstrated clear links between PPGV and conditions associated with sympathetic changes [5,7,10,11,16,17,26], no study has ever been performed to establish a relationship between the spectral pattern of PPGV and a quantitative measure of vascular tone. In addition, since the suppression of sympathetic vascular tone could lead to a relative dominance of HF over LF power in PPGV [11,26], we also examined whether the PPGV spectral powers were useful for the categorical identification of patients in highly vasodilated states (indicated by the low SVR).…”

“…Infrared light can penetrate deep into the skin and subcutaneous tissue and is relatively insensitive to blood oxygenation [8,12], thus the resultant PPG signal reflects total blood volume change in the fingertip circulation, under the combined influences of central perfusion pressure and local sympathetic vascular control [2]. Similar to BPV, the frequency spectrum of PPG variability (PPGV) consists of both low frequency (LF) vasomotor waves, and high frequency (HF) respiratory fluctuations [5,10,11,16,17,23,26]. Sympathetic activation induced by active standing has been shown to augment normalized LF power of PPGV [5,17], whereas suppression of basal sympathetic tone by induction of anesthesia leads to a relative reduction in LF and enhancement of HF fluctuations [11,26].…”

“…Sympathetic activation induced by active standing has been shown to augment normalized LF power of PPGV [5,17], whereas suppression of basal sympathetic tone by induction of anesthesia leads to a relative reduction in LF and enhancement of HF fluctuations [11,26]. Recent studies by our group have highlighted the potential of PPGV for identifying changes in sympathetic vascular control associated with various critical conditions in the clinical setting, including blood volume loss, sepsis, and endotoxic shock [7,10,16,31], and raised the exciting possibility of detecting these complications at an early stage using an easy-to-measure non-invasive PPG signal.…”

Reconstruction of gastric slow wave from finger photoplethysmographic signal using radial basis function neural network

“…It is well-known that PPG signal contains information related to the cardiovascular dynamics. Some low frequency oscillations in PPG also reflect the function of autonomic nervous system [11,23,24]. The sources of these frequency components may be blood pressure control, thermoregulation, central baroreflex activity, vasomotoric rhythms, autonomous nervous system (ANS), neurogenic activity, myogenic rhythm, sympathetic modulation of peripheral vasculature (e.g., finger skin), and heart-synchronous pulse waveform [11,14,23,25,32].…”

“…Some low frequency oscillations in PPG also reflect the function of autonomic nervous system [11,23,24]. The sources of these frequency components may be blood pressure control, thermoregulation, central baroreflex activity, vasomotoric rhythms, autonomous nervous system (ANS), neurogenic activity, myogenic rhythm, sympathetic modulation of peripheral vasculature (e.g., finger skin), and heart-synchronous pulse waveform [11,14,23,25,32]. Other than the cardiac and respiratory rhythm, the sources of the low frequency oscillations present in PPG signal are not fully understood because of the highly complicated nature of the circulatory system, especially the interaction between the circulatory system and the ANS [15,24].…”