Anatomy and Physiology of Ageing
Dr Reena Hacking, Specialist Registrar, Anaesthesia, Imperial School of
Dr Dominic O’Connor, Consultant Anaesthetist, Royal Perth Hospital,
1. Why do elderly patients have decreased arterial oxygen tension on blood
gas analysis when compared to younger patients?
2. What physiological changes to the cardiovascular system occur in the
3. Why are elderly patients at increased risk of hypotension during
induction of anaesthesia?
4. What are the effects of ageing on skin, bones and joints and what
implications do these changes have for the anaesthetist?
The elderly population is increasing in size as people are living longer due to
advances in medical science and improvements in standards of living. In the
western world people over 65 years of age represent approximately 15% of the
population and almost half of these individuals will present to hospital for a
surgical procedure. Elderly patients have higher rates of hospital morbidity and
mortality compared to younger patients. This increased risk is related to the
normal physiological processes of ageing and increased prevalence of coexisting
As a person ages, their anatomy and physiology undergo many changes that
become more apparent with increasing chronological age. Ageing is a
progressive physiological process that is characterised by degeneration of organ
systems and tissues with consequent loss of functional reserve of these systems.
Loss of these functional reserves impairs an individual’s ability to cope with
physiological challenges such as anaesthesia and surgery.
Individuals of the same chronological age may differ significantly in the rate and
severity of functional decline. Patients who maintain greater than average
functional capacity are considered ‘physiologically young’ and those whose
function declines at an earlier age appear to be ‘phys