Physiologic change of aging

Older adults are not adults with grey hair. It is the same principle for pediatrics, they have their own physiologic particularities. These differences are very important to understand because it will change the clinical management.

Lets review what happens when the body ages, starting at 25 years old! (Oh yes!)

But first, I would like to point out something very important. Physiological changes of aging are NORMAL, not pathologic. For example, cerebral atrophy with age is normal, dementia is a disease.

Lets review system by system with its clinical application.

Neurological system:

  • Impaired thermoregulation -> Be careful in resus, cover your patient.
  • Impaired BBB permeability -> Increased risk of meningitis and increased adverse drug reaction (caution with neuro sensitive medication, dosage, etc)
  • Alteration of the autonomic nervous system -> increased risk of orthostatism leading to fall

Cardiovascular system:

  • Stiff pump -> decreased ventricular filling and more dependant on the atrial kick meaning that patient in atrial fibrillation can be more easily impaired hemodynamically.
  • Stiff pipes -> Altered response to volume change (hypertension with overflow, orthostatism with hypovolemia)
  • Alteration in the electric system -> less capacity to increase heart rate in response to stress

Pulmonary system:

  • Decreased vital capacity and impaired diffusion capacity -> less gas exchange
  • Less respiratory muscle strength -> potential for rapid decompensation in the event of an acute pulmonary disease

Hepatic system:

  • Decreased hepatic mass, blood flow and enzyme activity -> alteration in pharmacokinetics meaning more drug interactions and adverse drugs reactions

Renal system:

  • Decreased renal mass and decreased body water -> drugs accumulation, decreased creatinine clearance
  • Decreased vit D metabolism -> increased risk of osteoporosis

Gastro-intestinal system:

  • Decreased gastric mucosa, blood flow and bicarbonate secretion -> increased risk of ulcer and perforation in the presence of other risk factor
  • Decreased motility -> more constipation

Genito-urinary system:

  • Enlargment of prostate -> increased risk of retention and UTIs
  • Vaginal atrophy -> Increased risk of UTIs
  • alteration of the autonomic nervous system -> increased risk of incontinence and UTIs

Skin, muscle, mucosa systems:

  • Skin atrophy: decreased insulation and increased risk of decubitus ulcer
  • Switch in the proportion of adipose tissue (more) and lean mass (less) -> alteration in the pharmacokinetics, potential for accumulation of fat-soluble drugs and stronger effect because of reduced distribution volume
  • Atrophy of the fibrocartilaginous and synovial tissues -> increased risk of osteoarthritis and pain

This is a very brief summary of what I think is important to know about the foundation of geriatric. Back to basics, it is always a good thing and help build on new knowledges!

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