University of Twente Student Theses


Orthostatic blood pressure and its relation to cerebral autoregulation and resilience

Verkaar, L.T.K.M. (2023) Orthostatic blood pressure and its relation to cerebral autoregulation and resilience.

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Abstract:Blood pressure regulation is important to ensure a sufficient supply of blood to all organs. Gravitational force affects blood pressure, as blood needs to be redistributed. This research focuses on two different aspects of blood pressure regulation. (1) Blood pressure dysregulation and blood flow to the brain in patients with orthostatic hypotension (OH) was explored, zooming in on symptoms of dizziness after standing. These were hypothesized to be influenced by cerebral autoregulation. (2) Furthermore, the blood pressure response after standing up was studied in relation to frailty, resilience, and surgical outcome. The hypothesis was that patients with an incomplete blood pressure recovery were more frail and less resilient. Methods: (1) Near-infrared spectroscopy (NIRS) and blood pressure signals were explored in the time and frequency domain. Patients performed three supine stand tests and a repeated-sit-stand test. Initial drops and recovery values were computed with the supine stand test data, in the time domain. In frequency domain transfer function analyses (TFA) with oxyHb and deoxyHb was used to quantify cerebral autoregulation. (2) During a preoperative screening patients underwent a supine stand test while continuous blood pressure was measured. Principal component analysis was used to divide patients into groups based on their blood pressure curves. Patients were also divided into tertiles based on their Comprehensive Geriatric Assessment Frailty Index (CGA-FI). Results: (1) Patients with symptoms and OH seemed to have a lower drop in oxyHb than the other groups (p=0.583). Furthermore, no differences were found between patients with and without symptoms in the TFA results. (2) Patients with a blood pressure recovery after standing above baseline, appeared to be more frail than patients with other blood pressure patterns, but this was not significant. Patients, where the continuous blood pressure measurement failed were the most frail patients. No differences were found in surgery outcomes between groups with different blood pressure patterns. Discussion/conclusion: (1) OxyHb contains information about symptoms after standing up. No differences in cerebral autoregulation were found between patients with and without symptoms. (2) The results suggest that orthostatic hypertension could be a marker of frailty, although an incomplete blood pressure is related to frailty and mortality in literature. Therefore, it is possible that orthostatic hypertension and OH can both be markers of frailty.
Item Type:Essay (Master)
Radboud umc, Nijmegen, The Netherlands
Faculty:TNW: Science and Technology
Subject:44 medicine
Programme:Technical Medicine MSc (60033)
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