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High-Pass Filter Characteristics of the Baroreflex – A Comparison of Frequency Domain and Pharmacological Methods
Pharmacological methods to assess baroreflex sensitivity evoke supra-physiological blood pressure changes whereas computational methods use spontaneous fluctuations of blood pressure. The relationships among the different baroreflex assessment methods are still not fully understood. Although strong...
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Public Library of Science
2013
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3828383/ https://www.ncbi.nlm.nih.gov/pubmed/24244518 http://dx.doi.org/10.1371/journal.pone.0079513 |
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author | Bonyhay, Istvan Risk, Marcelo Freeman, Roy |
author_facet | Bonyhay, Istvan Risk, Marcelo Freeman, Roy |
author_sort | Bonyhay, Istvan |
collection | PubMed |
description | Pharmacological methods to assess baroreflex sensitivity evoke supra-physiological blood pressure changes whereas computational methods use spontaneous fluctuations of blood pressure. The relationships among the different baroreflex assessment methods are still not fully understood. Although strong advocates for each technique exist, the differences between these methods need further clarification. Understanding the differences between pharmacological and spontaneous baroreflex methods could provide important insight into the baroreflex physiology. We compared the modified Oxford baroreflex gain and the transfer function modulus between spontaneous RR interval and blood pressure fluctuations in 18 healthy subjects (age: 39±10 yrs., BMI: 26±4.9). The transfer function was calculated over the low-frequency range of the RR interval and systolic blood pressure oscillations during random-frequency paced breathing. The average modified Oxford baroreflex gain was lower than the average transfer function modulus (15.7±9.2 ms/mmHg vs. 19.4±10.5 ms/mmHg, P<0.05). The difference between the two baroreflex measures within the individual subjects comprised a systematic difference (relative mean difference: 20.7%) and a random variance (typical error: 3.9 ms/mmHg). The transfer function modulus gradually increased with the frequency within the low-frequency range (LF), on average from 10.4±7.3 ms/mmHg to 21.2±9.8 ms/mmHg across subjects. Narrowing the zone of interest within the LF band produced a decrease in both the systematic difference (relative mean difference: 0.5%) and the random variance (typical error: 2.1 ms/mmHg) between the modified Oxford gain and the transfer function modulus. Our data suggest that the frequency dependent increase in low-frequency transfer function modulus between RR interval and blood pressure fluctuations contributes to both the systematic difference (bias) and the random variance (error) between the pharmacological and transfer function baroreflex measures. This finding suggests that both methodological and physiological factors underlie the observed disagreement between the pharmacological and the transfer function method. Thus both baroreflex measures contribute complementary information and can be considered valid methods for baroreflex sensitivity assessment. |
format | Online Article Text |
id | pubmed-3828383 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2013 |
publisher | Public Library of Science |
record_format | MEDLINE/PubMed |
spelling | pubmed-38283832013-11-16 High-Pass Filter Characteristics of the Baroreflex – A Comparison of Frequency Domain and Pharmacological Methods Bonyhay, Istvan Risk, Marcelo Freeman, Roy PLoS One Research Article Pharmacological methods to assess baroreflex sensitivity evoke supra-physiological blood pressure changes whereas computational methods use spontaneous fluctuations of blood pressure. The relationships among the different baroreflex assessment methods are still not fully understood. Although strong advocates for each technique exist, the differences between these methods need further clarification. Understanding the differences between pharmacological and spontaneous baroreflex methods could provide important insight into the baroreflex physiology. We compared the modified Oxford baroreflex gain and the transfer function modulus between spontaneous RR interval and blood pressure fluctuations in 18 healthy subjects (age: 39±10 yrs., BMI: 26±4.9). The transfer function was calculated over the low-frequency range of the RR interval and systolic blood pressure oscillations during random-frequency paced breathing. The average modified Oxford baroreflex gain was lower than the average transfer function modulus (15.7±9.2 ms/mmHg vs. 19.4±10.5 ms/mmHg, P<0.05). The difference between the two baroreflex measures within the individual subjects comprised a systematic difference (relative mean difference: 20.7%) and a random variance (typical error: 3.9 ms/mmHg). The transfer function modulus gradually increased with the frequency within the low-frequency range (LF), on average from 10.4±7.3 ms/mmHg to 21.2±9.8 ms/mmHg across subjects. Narrowing the zone of interest within the LF band produced a decrease in both the systematic difference (relative mean difference: 0.5%) and the random variance (typical error: 2.1 ms/mmHg) between the modified Oxford gain and the transfer function modulus. Our data suggest that the frequency dependent increase in low-frequency transfer function modulus between RR interval and blood pressure fluctuations contributes to both the systematic difference (bias) and the random variance (error) between the pharmacological and transfer function baroreflex measures. This finding suggests that both methodological and physiological factors underlie the observed disagreement between the pharmacological and the transfer function method. Thus both baroreflex measures contribute complementary information and can be considered valid methods for baroreflex sensitivity assessment. Public Library of Science 2013-11-14 /pmc/articles/PMC3828383/ /pubmed/24244518 http://dx.doi.org/10.1371/journal.pone.0079513 Text en © 2013 Bonyhay et al http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited. |
spellingShingle | Research Article Bonyhay, Istvan Risk, Marcelo Freeman, Roy High-Pass Filter Characteristics of the Baroreflex – A Comparison of Frequency Domain and Pharmacological Methods |
title | High-Pass Filter Characteristics of the Baroreflex – A Comparison of Frequency Domain and Pharmacological Methods |
title_full | High-Pass Filter Characteristics of the Baroreflex – A Comparison of Frequency Domain and Pharmacological Methods |
title_fullStr | High-Pass Filter Characteristics of the Baroreflex – A Comparison of Frequency Domain and Pharmacological Methods |
title_full_unstemmed | High-Pass Filter Characteristics of the Baroreflex – A Comparison of Frequency Domain and Pharmacological Methods |
title_short | High-Pass Filter Characteristics of the Baroreflex – A Comparison of Frequency Domain and Pharmacological Methods |
title_sort | high-pass filter characteristics of the baroreflex – a comparison of frequency domain and pharmacological methods |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3828383/ https://www.ncbi.nlm.nih.gov/pubmed/24244518 http://dx.doi.org/10.1371/journal.pone.0079513 |
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