Peripheral photoplethysmography variability analysis of sepsis patients

Abstract

Sepsis is associated with impairment in autonomic regulatory function. This work investigates the application of heart rate and photoplethysmogram (PPG) waveform variability analysis in differentiating two categories of sepsis, namely systemic inflammatory response syndrome (SIRS) and severe sepsis. Electrocardiogram-derived heart period (RRi) and PPG waveforms, measured from fingertips (Fin-PPG) and earlobes (Ear-PPG), of Emergency Department sepsis patients (n = 28) with different disease severity, were analysed by spectral technique, and were compared to control subjects (n = 10) in supine and 80° head-up tilted positions. Analysis of covariance (ANCOVA) was applied to adjust for the confounding factor of age. Low-frequency (LF, 0.04-0.15 Hz), mid-frequency (MF, 0.09-0.15 Hz) and high-frequency (HF, 0.15-0.60 Hz) powers were computed. The normalised MF power in Ear-PPG (MFnu(Ear)) was significantly reduced in severe sepsis patients with hyperlactataemia (lactate > 2 mmol/l), compared to SIRS patients (P < 0.05). Moreover, in a group of normal controls, MFnu(Ear) was not altered by head-up tilting (P > 0.05), suggesting that there may be a link between 0.1 Hz ear blood flow oscillation and tissue metabolic changes in sepsis, in addition to autonomic factors. The study highlighted the value of PPG spectral analysis in the non-invasive assessment of peripheral vascular regulation in sepsis patients, with potential implications in monitoring the progression of sepsis.

Investigation of photoplethysmographic signals and blood oxygen saturation values on healthy volunteers during cuff-induced hypoperfusion using a multimode PPG/SpO2 sensor

“…Apart from PPG signals being used in estimation of the SpO 2 values, these volumetric changes in the finger PPG signal appear as an information source for several indirect measurement methods [4,7,12]. In a previous study [6], a moderate correlation (r = 0.54) was found between fingertip PPG waveform variability (PPGV) and systemic vascular resistance (SVR).…”

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].…”

“…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]. 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.…”

Method of estimation of synchronization strength between low-frequency oscillations in heart rate variability and photoplethysmographic waveform variability

“…The most popular opinion is that the low-frequency oscillations in PPGV characterize sympathetic regulation of peripheral vessels tone [26][27][28]. However, it is important to consider that PPG signal contains information about both peripheral blood flow (including microcirculatory bloodstream) and distal arterial bed [29].…”