Download Physiology of Aging

GERIATRICS: AN
OVERVIEW
AGS
Keerti Sharma, MD
Assistant Professor of
Medicine
THE AMERICAN GERIATRICS SOCIETY
Geriatrics Health Professionals.
Leading change. Improving care for older adults.
4 IMPORTANT TAKE-HOME POINTS
• Common diseases can have uncommon
presentations in the elderly
• Temptation to overtreat should be avoided
• Always start low and go slow when
prescribing medications
• A new symptom can be a medication side
effect
Slide 2
HISTORY
• Develop a symptom
• Perceive a symptom
• Communicate
Slide 3
REASONS FOR UNDERREPORTING
(THE ICEBERG PHENOMENON)
•
•
•
•
Fear of hospitalization
Fear of unpleasant investigations
Fear of treatment
Risk of involuntary removal to residential
care
• Imagining that symptoms are not amenable to
treatment
• Low health expectations
• Lack of Information
Slide 4
GOALS OF CARE
• Focus must remain on keeping the older
person functional
• If that goal becomes medically infeasible, the
patient’s dignity and comfort must then
become the primary focus
Slide 5
NORMAL AGING VERSUS
PATHOLOGICAL AGING
• Normal aging = aging-related changes
• Pathological aging = aging-associated
changes
• Normal aging:
 Involves a great number of biologic processes
 Is characterized by progressive, predictable, and
inevitable changes that are independent of
disease
Slide 6
PHYSIOLOGIC CHANGES
WITH AGING
GENERAL PRINCIPLES
OF NORMAL AGING
• Organs in the same person age at different
rates
• Determinants of these rates include genetic
makeup, personal choices, environmental
exposures, and other factors
• Aging changes are modifiable but inevitable
Slide 8
BLOOD PRESSURE REGULATION
• Higher risk for orthostatic or postural
hypotension
• Narrow range within which CNS perfusion
maintained
• Changes in antihypertensive drugs should be
based on patient’s standing blood pressure
Slide 9
CONTROL OF BODY TEMPERATURE
Increased susceptibility to both hypothermia
and hyperthermia
Slide 10
VOLUME REGULATION
• Predisposition to both volume depletion and
volume overload
• Decreased thirst
• Decreased ADH response to hypovolemia
and renal response to ADH
• Greater difficulty in excreting fluid overload
 Results in predisposition to hyponatremia and
CHF
Slide 11
BARRIER DEFENSES
• Skin’s effectiveness as a barrier is decreased
• Mucous membranes are less effective
barriers
• Ciliary clearance slows
• Repair rate of injured skin declines
• Disease affects wound healing
Slide 12
PHYSICAL AND MECHANICAL
DEFENSES
•
•
•
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Urine is less acidic
Prostatic fluid has less antibacterial activity
Bladder is less completely emptied
Colonization of the vagina is more likely in
estrogen-deficient women
• Greater susceptibility to UTI and incontinence
Slide 13
IMMUNE RESPONSE
• Afebrile infection is common
• Humoral antibody-mediated response is
decreased
• Antibody response to vaccine is decreased
• Response to tuberculosis skin test decreases
Slide 14
NERVOUS SYSTEM (1 of 2)
• The weight of the brain decreases
• The area of the cerebral ventricles may
increase 34
• Most prominent loss occurs in the largest
neurons
• Cognitive loss is not a part of normal aging
Slide 15
NERVOUS SYSTEM (2 of 2)
• Changes affect the older person’s ability to
distinguish between different stimuli
• Reduced reaction time, resulting possibly in
injuries and burns
• Reduced balance
• Greater risk of falls
Slide 16
VISION
• Iris becomes more rigid
• Lens yellows (due to photooxidation and
accumulation of insoluble protein)
• Increased sensitivity to glare
• Decreased static acuity and dynamic acuity
• Decline in contrast sensitivity
Slide 17
AVOID MOSAIC FLOOR PATTERNS
Slide 18
HEARING
• Drier cerumen, leading in greater risk of
impaction
• Tympanic membrane thickens
• Ossicles undergo degenerative changes
• Risk of high-frequency and low-frequency
hearing loss
Slide 19
TASTE AND SMELL
• Olfaction declines
 May lead to decreased enjoyment of food and
difficulty in sorting the tastes of mixed and
combined foods
• Gustatory function unchanged
Slide 20
CARDIOVASCULAR SYSTEM
• Blood vessels: increased intimal thickness,
increased wall thickness, increased smooth muscle
 Leads to increased systolic and pulse pressure
• Heart muscle: increased afterload
 Leads to LVH, decreased cardiac output
• Heart valves: left sides become sclerotic
• Response to sympathetic stimulation: reduced
 Leads to reduction in cardiac output during stress
(eg, surgery) and increased risk of CHF
Slide 21
RESPIRATORY SYSTEM
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•
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Decreased effectiveness of cough
Decline in PO2
Decreased pulmonary reserve during stress
Increased frequency of infection, increased
likelihood of hypoxia
Slide 22
GASTROINTESTINAL SYSTEM
(1 of 2)
• Less effective chewing, even with intact teeth
• Food is kept in the mouth longer and larger
pieces of food are swallowed
• Swallowing is less coordinated, which
increases the risk of aspiration
Slide 23
GASTROINTESTINAL SYSTEM
(2 of 2)
• Lactase levels decline and intolerance of
dairy products is common
• Colon: slowed transit and increase in opioid
receptor
 May predispose the older person to drug-induced
constipation
• Liver: after age 30 there is 1% per year
decline in liver mass and blood flow every
year
Slide 24
RENAL SYSTEM
• After age 20 GFR decreases 0.5% per year
and renal blood flow decreases 1% per year
• Serum creatinine is an imperfect marker of
renal function in the elderly
• Increased likelihood of adverse outcome from
drugs with narrow therapeutic margins (eg,
digoxin, aminoglycosides)
Slide 25
MUSCULAR SYSTEM (1 of 2)
Age-related decrease in muscle mass and
quality (sarcopenia)
Slide 26
MUSCULAR SYSTEM (2 of 2)
• Lower-extremity strength is lost at a faster
rate than upper-extremity strength
• Water content decreases in tendons and
ligaments, and stiffness increases
Slide 27
ENDOCRINE SYSTEM
• Slight increase in fasting glucose, not
clinically significant
• Thyroid hormone levels unchanged
• Vitamin D levels decline
Slide 28
ANATOMY
• Loss of height: 5-cm decrease by age 75 due
to increased hip and knee flexion, decreased
vertebral body height, vertebral disc
compaction, and flattening of foot arch
• Fat compartment expands with age
• Total body weight unchanged because of
decrease in lean body mass
Slide 29
COAGULATION
• No change in the absolute number of RBC,
WBC, platelets
• Chronic low-grade activation of clotting
pathways
• Doubling of d-dimer
• ESR rate increases with age
 Women = (age + 10) / 2
 Men = age / 2
Slide 30
ARTERIAL BLOOD GASES
• Arterial pH and PCO2 do not change with age
• Arterial oxygen content and PO2 decline (3
mm Hg per decade)
100  (age / 3)
Slide 31
SERUM CHEMISTRY
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•
•
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Electrolytes unchanged
Creatinine unchanged
Minor decline in total protein and albumin
Uric acid and alkaline phosphatase increase
slightly
Slide 32
CHANGES IN THE
PHYSICAL EXAMINATION
POSSIBLE EXPLANATIONS
• Multiple comorbidities
• Age-related physiological changes may alter
perception to stimulus
• Cognitive impairment may prevent patient
from providing an accurate history
Slide 34
GASTROINTESTINAL DISEASES
• Achalasia: lower incidence of chest pain
• Respond equally well to pneumatic dilation
Slide 35
INTRA-ABDOMINAL INFECTIONS
• Less likely to have nausea, vomiting or fever
• More likely to be hypothermic and
neutropenic
• More likely to have biliary or pancreatic
sources
• Associated with significant mortality and
morbidity
Slide 36
APPENDICITIS
• Although more common in the young,
associated with higher mortality in the elderly
• Abdominal rigidity, decreased bowel sounds,
and the presence of a mass appear to be
more common in older patients
Slide 37
CHOLECYSTITIS
May not present with the classic symptoms
Slide 38
BACTEREMIA
• Less likely to have fever, rigors, and chills
• More likely to have delirium, weakness, or fall
Slide 39
MYOCARDIAL INFARCTION
• Dyspnea and CHF are common
• Delirium was presenting symptom in 13%
• Syncope and stroke were presenting
symptoms in 7%
Slide 40
PNEUMONIA
• Atypical presentations occur more frequently
• Nonspecific deterioration in a patient’s health
status: decreased oral intake, fall, and
confusion
• Abrupt worsening of an underlying chronic
medical condition
Slide 41
URINARY TRACT INFECTION
AND UROSEPSIS
• Bacteriuria is increasingly common with
advancing age
• Lower tract infections (dysuria, urgency,
suprapubic pain) usually missing
• Upper urinary tract infection (flank pain, fever,
and chills) usually missing
• Confusion is a common presenting sign
Slide 42
WORKUP
• Avoid the temptation to overtreat
• Treatment side effects must never be worse
than the disease
Slide 43
4 IMPORTANT TAKE-HOME POINTS
• Common diseases can have uncommon
presentations in the elderly
• Temptation to overtreat should be avoided
• Always start low and go slow when
prescribing medications
• A new symptom can be a medication side
effect
Slide 44
THANK YOU FOR YOUR TIME!
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