Reports of research work funded by grants prior to 2013
University of Otago Wellington, School of Medicine and Health Sciences
Reproducibility of the Sit-to-stand Manoeuvre to assess Baroreflex Function
KC Peebles, HM Horsman and Y-C (Shieak) Tzeng
Cardiovascular Systems Laboratory, Department of Surgery and Anaesthesia
Purpose of the study
The arterial baroreflex is an important blood pressure control mechanism. Impairment of baroreflex sensitivity (BRS) is associated with a range of cardiovascular pathologies such as hypertension, stroke and heart failure. Hence accurate assessment of the baroreflex has important prognostic and diagnostic implications.
The sit-to-stand manoeuvre is a simple and relatively new test to assess BRS. This method involves actively moving from sitting to standing (and vice-versa) to evoke transient reductions (and increases) in blood pressure at a given frequency. Thereby acknowledging the fact that the baroreflex function is influenced by both the rate (frequency) and magnitude of blood pressure perturbations. To date the sit-to-stand manoeuvre has not been widely adopted in the clinical setting. This is surprising given that it is easy to perform, does not involve pharmacological agents and incorporates a frequency component, which yields important information about the speed (and potential mediators) of this homeostatic mechanism. Perhaps part of the reason is that the reproducibility and reliability of this method, which would aid its adoption into the clinical setting, has not been assessed.
Thus, the main purpose of the present study was to: i) examine the reproducibility and reliability of the sit-to-stand manoeuvre; and ii) compare the reproducibility and reliability of the sit-to stand manoeuvre to that of the modified Oxford method (pharmacologically-induced blood pressure changes) and the Valsalva manoeuvre, (respiratory-induced blood pressure changes), which are commonly used to assess BRS in the research and clinical environments, respectively.
In addition, by separately analysing BRS during increases and decreases in blood pressure we evaluated baroreflex hysteresis (another important property of the baroreflex) during the sit-to stand manoeuvre, for the first time.
Progress to date
We have collected complete data from 16 participants and data (including statistical) analysis is well underway. We are also in the preliminary stages of drafting a manuscript, which we intend to submit in the next six months.