An exploration of gait parameters and heart rate recovery in older adults with orthostatic hypotension

Abstract

It is known that there is an ageing population globally, and with ageing comes physiological and function decline. The prevalence of many health conditions increases with advancing age, including orthostatic hypotension. This is a clinical condition characterised by a sustained reduction of at least 20 mmHg in systolic blood pressure and/or at least 10mmHg in diastolic blood pressure within three minutes of standing or head-up tilt to at least 60°. Orthostatic hypotension can impact health and function of an individual and has been identified as a risk factor in older adults for falls, stroke, and frailty, among other adverse outcomes. Human gait patterns are highly variable and gait abnormalities also increase in prevalence with advancing age. These abnormalities can contribute to falls, loss of independence, and reduced quality of life.

The primary aim of Study I (Chapter 3) was to investigate the effect of impaired orthostatic blood pressure responses in older adults on gait parameters using measures obtained from the GAITRite system in a nationally representative cohort. Data from the Wave 3 health assessment of TILDA were examined to assess this relationship. No differences in gait parameters were identified between those with and without impaired orthostatic blood pressure responses. However, when age was considered, increases in gait velocity and step length were observed in those with impaired orthostatic blood pressure responses.

Consequently, the immediate impact of posture change on gait parameters in those with and without initial orthostatic hypotension was investigated in Study II (Chapter 4). Participants with and without initial orthostatic hypotension performed three gait assessments while examinations were performed using gait laboratory analysis: sit-to-stand walking, usual walking, and dual task walking. In agreement with Study I, increases in gait velocity and step length were identified in those with initial orthostatic hypotension. No significant changes in gait parameters were observed following sit-to-stand compared to usual walking.

Considering the assessment for orthostatic hypotension involves a lie-to-stand, Study III (Chapter 5) investigated gait parameters following a lie-to-stand transition. Reductions were demonstrated in gait velocity and step length during lie-to-stand walking compared to usual walking. In Studies II and III NIRS investigations were performed throughout the assessment, however data obtained were inconsistent.

Complex interplay between heart rate and blood pressure occurs during orthostatic manoeuvres. Evidence regarding the orthostatic heart rate response is lacking, so Study IV (Chapter 6) aimed to determine the repeatability of heart rate recovery in response to the active stand. Broad limits of agreement for repeated measures of the response were observed. Age-related differences in the response were demonstrated in this study, with greatest repeatability in adults over 51 years of age.

The findings in this PhD have identified alterations in gait parameters in older adults with initial orthostatic hypotension which contrast with previous findings. This highlights the need for greater consideration of initial orthostatic hypotension and the impact it may have. Furthermore, the orthostatic heart rate response is an underutilised vital sign which may complement investigations regarding orthostatic hypotension. Further research is required to expand on the findings of this research project to better understand the causes and implications of the changes in function observed with advancing age.