Geriatric Physiology

Question 1

What are the physiological effects of increasing age?

Answer 1

General Considerations Progressive (often undiagnosed) comorbidity in each system
IHD, HTN, COPD, Cognitive dysfunction & sensory impairment, cancer
Polypharmacy - drug interactions & SE)
Autonomic dysfunction

Airway
Teeth - may be edentulous or have expensive bridges/dentures
TMJ dysfunction, cervical spondylosis/arthritis

Respiratory
Reduced FRC, encroaching on increasing closing capacity - small airway closure occurs with tidal breathing when supine.
Reduced sensitivity to hypoxia/hypercapnoea
Increased V/Q mismatch, increased A:a gradient
Reduced compliance (although increased compliance with gas trapping in emphysaema)
Higher risk of Post-op atelectasis & pneumonia

Cardiovascular
Reduced CO
About 20% reduction by 60 years (reduced HR, SV & contractility)
Reduced sensitivity to catecholamines, vasopressors & inotropes
Orthostatic hypotension
Higher risk of thromboembolism

Neurological
Cerebral atrophy (10% reduced brain weight) - worse short term memory, higher risk of delirium
Reduced cerebral blood flow & metabolism - lower MAC required, and increased sensitivity to benzos/opioids

GI
Hiatus hernia, delayed gastric emptying

Renal & Hepatic
Reduced blood flow & GFR (40% lower), reduced drug clearance
Reduced hepatic metabolism

Metabolic & Endocrine
Reduced BMR, less effective temperature regulation