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Photoplethysmography for Quantitative Assessment of Sympathetic Nerve Activity (SNA) During Cold Stress

The differences in the degree of sympathetic nerve activity (SNA) over cutaneous blood vessels, although known to be more prominent in the periphery than the core vasculature, has not been thoroughly investigated quantitatively. Hence, two studies were carried out to investigate the differences in S...

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Autores principales: Budidha, Karthik, Kyriacou, Panayiotis A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Frontiers Media S.A. 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6338034/
https://www.ncbi.nlm.nih.gov/pubmed/30687108
http://dx.doi.org/10.3389/fphys.2018.01863
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author Budidha, Karthik
Kyriacou, Panayiotis A.
author_facet Budidha, Karthik
Kyriacou, Panayiotis A.
author_sort Budidha, Karthik
collection PubMed
description The differences in the degree of sympathetic nerve activity (SNA) over cutaneous blood vessels, although known to be more prominent in the periphery than the core vasculature, has not been thoroughly investigated quantitatively. Hence, two studies were carried out to investigate the differences in SNA between the periphery and the core during the cold pressor test (CPT) (right-hand immersion in ice water) and cold exposure (whole body exposed to cold air) using photoplethysmography (PPG). Two methods utilizing PPG, namely differential multi-site PTT measurements and low-frequency spectral analysis were explored for quantitative determination of SNA. Each study involved 12 healthy volunteers, and PPG signals were acquired from the right index finger (RIF), left index finger (LIF) (periphery) and the ear canal (core). During CPT, Pulse Transit Time (PTT) was measured to the respective locations and the mean percentage change in PTT during ice immersion at each location was used as an indicator for the extent of SNA. During cold exposure, the low-frequency spectral analysis was performed on the acquired raw PPGs to extract the power of the sympathetic [low-frequency (LF): 0.04–0.15 Hz] and parasympathetic components [high-frequency (HF): 0.15–0.4 Hz]. The ratio of LF/HF components was then used to quantify the differences in the influence of SNA on the peripheral and core circulation. PTT measured from the EC, and the LIF has dropped by 5 and 7%, respectively during ice immersion. The RIF PTT, on the other hand, has dropped significantly (P < 0.05) by 12%. During the cold exposure, the LF/HF power ratio at the finger has increased to 86.4 during the cold exposure from 19.2 at the baseline (statistically significant P = 0.002). While the ear canal LF/HF ratio has decreased to 1.38 during the cold exposure from 1.62 at baseline (P = 0.781). From these observations, it is evident that differential PTT measurements or low-frequency analysis can be used to quantify SNA. The results also demonstrate the effectiveness of the central auto-regulation during both short and long-term stress stimulus as compared to the periphery.
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spelling pubmed-63380342019-01-25 Photoplethysmography for Quantitative Assessment of Sympathetic Nerve Activity (SNA) During Cold Stress Budidha, Karthik Kyriacou, Panayiotis A. Front Physiol Physiology The differences in the degree of sympathetic nerve activity (SNA) over cutaneous blood vessels, although known to be more prominent in the periphery than the core vasculature, has not been thoroughly investigated quantitatively. Hence, two studies were carried out to investigate the differences in SNA between the periphery and the core during the cold pressor test (CPT) (right-hand immersion in ice water) and cold exposure (whole body exposed to cold air) using photoplethysmography (PPG). Two methods utilizing PPG, namely differential multi-site PTT measurements and low-frequency spectral analysis were explored for quantitative determination of SNA. Each study involved 12 healthy volunteers, and PPG signals were acquired from the right index finger (RIF), left index finger (LIF) (periphery) and the ear canal (core). During CPT, Pulse Transit Time (PTT) was measured to the respective locations and the mean percentage change in PTT during ice immersion at each location was used as an indicator for the extent of SNA. During cold exposure, the low-frequency spectral analysis was performed on the acquired raw PPGs to extract the power of the sympathetic [low-frequency (LF): 0.04–0.15 Hz] and parasympathetic components [high-frequency (HF): 0.15–0.4 Hz]. The ratio of LF/HF components was then used to quantify the differences in the influence of SNA on the peripheral and core circulation. PTT measured from the EC, and the LIF has dropped by 5 and 7%, respectively during ice immersion. The RIF PTT, on the other hand, has dropped significantly (P < 0.05) by 12%. During the cold exposure, the LF/HF power ratio at the finger has increased to 86.4 during the cold exposure from 19.2 at the baseline (statistically significant P = 0.002). While the ear canal LF/HF ratio has decreased to 1.38 during the cold exposure from 1.62 at baseline (P = 0.781). From these observations, it is evident that differential PTT measurements or low-frequency analysis can be used to quantify SNA. The results also demonstrate the effectiveness of the central auto-regulation during both short and long-term stress stimulus as compared to the periphery. Frontiers Media S.A. 2019-01-09 /pmc/articles/PMC6338034/ /pubmed/30687108 http://dx.doi.org/10.3389/fphys.2018.01863 Text en Copyright © 2019 Budidha and Kyriacou. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
spellingShingle Physiology
Budidha, Karthik
Kyriacou, Panayiotis A.
Photoplethysmography for Quantitative Assessment of Sympathetic Nerve Activity (SNA) During Cold Stress
title Photoplethysmography for Quantitative Assessment of Sympathetic Nerve Activity (SNA) During Cold Stress
title_full Photoplethysmography for Quantitative Assessment of Sympathetic Nerve Activity (SNA) During Cold Stress
title_fullStr Photoplethysmography for Quantitative Assessment of Sympathetic Nerve Activity (SNA) During Cold Stress
title_full_unstemmed Photoplethysmography for Quantitative Assessment of Sympathetic Nerve Activity (SNA) During Cold Stress
title_short Photoplethysmography for Quantitative Assessment of Sympathetic Nerve Activity (SNA) During Cold Stress
title_sort photoplethysmography for quantitative assessment of sympathetic nerve activity (sna) during cold stress
topic Physiology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6338034/
https://www.ncbi.nlm.nih.gov/pubmed/30687108
http://dx.doi.org/10.3389/fphys.2018.01863
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