A Closed‐Loop Cardiovascular Model of the Supine‐To‐Stand Manoeuvre: Implications for Falls

ABSTRACT

The risk of falling increases with age and orthostatic hypotension (OH) is a common cardiovascular contributor. Current OH diagnostics rely on intermittent blood pressure measurements, which may not adequately characterise haemodynamic responses during orthostatic stress. We developed a closed‐loop cardiovascular lumped‐parameter model and fitting pipeline for continuous beat‐to‐beat blood pressure and heart rate data during a supine‐to‐stand manoeuvre, enabling model‐based evaluation of orthostatic haemodynamic responses in older adults. Our 23‐compartment lumped model included baroreflex and cardiopulmonary reflex regulation and was calibrated using Finapres data from older adults (Nijmegen Radboud University PROHEALTH study). Using a stochastic ranking evolutionary strategy, we fitted 31 parameters to averaged cohort data, classifying participants as with or without a history of falls (≥ 1 fall in the previous year). The model reproduced systolic and diastolic blood pressure and heart rate responses at the population level, with normalised root mean squared errors of 10.6% and 9.6% for participants with and without a history of falls, respectively. Four model parameters differed significantly between the two population‐average fits: baroreflex reference heart rate, a baroreflex transfer function parameter, transient external muscle pressure during standing, and total blood volume. These results demonstrate that a physiologically structured cardiovascular model can reproduce population‐level orthostatic responses in older adults and highlight model‐based parameter differences associated with fall history.