Bagnall Hare, Hasana
(2023)
Understanding the neural baroreflex:
Pulsatility, baroreflex sensitivity and
system identification -
experimentation and analysis.
PhD thesis, National University of Ireland Maynooth.
Abstract
Blood pressure is a dynamic measurement that continuously changes based on a
variety of physiological needs. Adequate blood pressure is crucial for a variety of
reasons, such as organ perfusion, oxygen circulation, and the excretion of harmful
toxins. Prolonged periods of blood pressure abnormalities, such as hypotension and
hypertension, can lead to an array of adverse events, including myocardial infarction
and stroke. Understanding blood pressure dynamics can aid the early diagnosis and
slow the development of adverse cardiovascular conditions. This thesis aims to provide
additional information about the neural baroreflex, the short term regulator of blood
pressure.
A protocol to characterise the neural baroreflex from data recorded, where the
baroreceptors remain intact, is presented. The method allows for both time- and
frequency- domain model identification that accurately represent the neural baroreflex.
Mayer waves, or low-frequency oscillations, are observed in blood pressure readings,
occurring at approximately 0.1Hz in humans. The origin and prognostic value of these
waves are currently being explored. In this thesis, a baroreflex model is extended
to include compliance and pulsatility. This model is then used to determine the
conditions under which low-frequency oscillations occur, with a focus on the effect of
blood pressure pulsatility on their presence. The analysis suggests that as pulsatility
decreases, the incidence of Mayer waves increases. This hypothesis is then examined
experimentally.
The functionality of the baroreflex is evaluated through baroreflex sensitivity estimation.
A decrease in baroreflex sensitivity has been proven to be a reliable indicator of adverse
cardiovascular events. The current gold standard is the Oxford method, an invasive
procedure that cannot be performed in routine clinical settings. Hence, there is a need
for a non-invasive alternative. This thesis examines the viability of sequence methods,
a popular non-invasive alternative, as a reliable estimation method.
This thesis explores a collection of studies which, individually, have their own unique
contributions. However, collectively the studies work to increase the understanding
of blood pressure regulation, providing insight to aid the development of baroreflex
assessment methods and potentially aid the identification of potential sources of
baroreflex dysregulation.
| Item Type: |
Thesis
(PhD)
|
| Keywords: |
neural baroreflex;
Pulsatility; baroreflex sensitivity;
system identification; experimentation and analysis; |
| Academic Unit: |
Faculty of Science and Engineering > Electronic Engineering |
| Item ID: |
18625 |
| Depositing User: |
IR eTheses
|
| Date Deposited: |
10 Jun 2024 11:18 |
| URI: |
|
| Use Licence: |
This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available
here |
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