Haemodynamic Vulnerability: An Integrative Physiological Framework for Understanding Hypotension in Older Adults

Background: Hypotension in older adults is usually classified into distinct syndromes (orthostatic, postprandial, neurogenic, medication-related and illness-associated) that differ in mechanism, yet frequently coexist and are poorly explained by resting blood pressure. Content: We review how structural and functional cardiovascular ageing progressively erodes integrated haemodynamic reserve across six domains: cardiac, arterial, venous (preload), autonomic, renal/neurohumoral and regional autoregulatory. On this basis, we propose haemodynamic vulnerability as a physiological framework: a latent state of reduced integrated haemodynamic reserve that could, in future studies, be identified by abnormal responses to standardized challenges falling short of the diagnostic criteria for hypotension. We distinguish it from normal cardiovascular ageing and from related concepts (physiological reserve, frailty, resilience and haemodynamic frailty), propose an operational definition with testable predictions, outline candidate indices of reserve and resilience, and consider the potential contribution of artificial intelligence. Clinical implications: The framework shifts attention from resting blood pressure to haemodynamic competence, the ability to maintain blood pressure and organ perfusion under stress, and helps explain the overlap between hypotensive phenotypes. Conclusions: Haemodynamic vulnerability links cardiovascular ageing to the different hypotensive phenotypes. Prospective validation is required before it can support risk stratification and clinical decision-making.