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Clinical Implications of the
Aging Physiology
Anita Chopra, MD
Director, NJISA
UMDNJ-SOM
Clinical Implications of the
Aging Physiology
This Care of the Aging Medical Patient in
the Emergency Room (CAMPER)
presentation is offered by the Department of
Emergency Medicine in coordination with the
New Jersey Institute for Successful Aging.
This lecture series is supported by an educational grant from the
Donald W. Reynolds Foundation Aging and Quality of Life
program.
Learning Objectives
• Describe the concept of homeostenosis
• Review the physiological changes associated
with age in various systems of the body
• Discuss the significance of age associated
physiologic changes on the clinical presentation
and management of older patients
An 82 year old female presents with increasing shortness
of breath and fatigue for the last few days. She has a
history of hypertension, diabetes mellitus type 2, and
osteoarthritis of the knees. Her medications include
glyburide 5 mg daily, hydrochlorothiazide 25 mg daily,
lisinopril 10 mg daily, and Ibuprofen 200 mg once daily
as needed. BP is 110/70, resp. 20/minute, pulse is
irregular. Lungs reveal bibasilar crackles and there is
trace pedal edema. PaO2 on room air is 65. EKG
reveals
Which age-related physiologic change makes her
more vulnerable to develop symptoms of CHF?
A. Decline in renal function
B. Hypoxia
C. Increase in atrial natriuretic peptide (ANP)
levels
D. Increase in BP
E. Tachycardia and loss of atrial kick
An 80 year old white male complains of mild shortness
of breath on exertion. He denies any chest pain,
wheezing, or cough. There is no history of hypertension
or CAD. He denies a history of smoking. On
examination, his lungs are clear with no crackles or
wheezing. X-ray of the chest and electrocardiogram
reveal normal findings. Patient is referred for pulmonary
function testing.
Which of the following describes expected agerelated changes in pulmonary function?
A. Decreased total lung capacity, decreased FEV1,
decreased residual volume
B. Increased total lung capacity, decreased FEV1
and decreased residual volume
C. Increased total lung capacity, decreased FEV1
and increased residual volume
D. Stable total lung capacity, decreased vital capacity,
decreased residual volume
E. Stable total lung capacity, decreased vital capacity,
increased residual volume
Which aspect of renal function is relatively
maintained with aging ?
A.
B.
C.
D.
E.
Ability to excrete acid load
Concentrating capacity
Diluting capacity
Erythropoietin production
Metabolism of parathyroid hormone
Aging
• Normal aging is not a disease
• Chronologic age & physiologic age are not
the same
• Individuals “age” at different rates and
there is significant variability
• Increased susceptibility to diseases
Spectrum Of Aging
• Aging, with disease and disability
• Usual aging, with the absence of overt
pathology, but with some declines in
function
• Successful aging or healthy aging, with little or no
pathology and little or no functional loss
Aging and Disease
• “Homeostenosis”: Diminished ability to maintain
homeostasis under stress
• Diseases can present atypically in old age
• Disease in old age is usually modified (presentation,
clinical course, response to treatment, outcomes) by
interaction with age-related changes
• Geriatric Syndromes are the result of interaction of
physiologic changes of aging, diseases and risk factors
Aging and Physiologic Rhythms
• Attenuation of pulsatile secretion of hormones (e.g.,
melatonin, ACTH, TSH, LH/FSH, GH)
• Reduction in circadian amplitude of physiologic
processes
– Plasma cortisol
– Sleep
– Body temperature
• Loss of complexity in physiologic functions may
contribute to impaired response to stressors
Age-related decline in heart rate variability could be due to: (1) dropout
of sinus node cells, (2) altered ß-adrenergic receptor responsiveness, and
(3) an apparent reduction in the parasympathetic tone
Aging and Homeostatic Challenges
• Blood pressure regulation
• Volume regulation
• Temperature regulation
An 80 year old male presents with complaints
of dizziness, especially in the early afternoon.
He reports that that he has "fainted" once, but
was not seriously injured at this time. His
medical history includes COPD, peripheral
vascular disease, and hypertension. His
hypertension is currently treated with
hydrochlorothiazide 25mg QD and felodipine 5
mg QD.
What age related changes are contributing to
his dizziness/syncope?
A.
B.
C.
D.
E.
Decreases fluid volume
Impaired cerebral auto regulation
Orthostatic hypotension
Postprandial hypotension
All of the above
Aging and Blood Pressure Regulation
• Baroreflex response to arterial pressure changes
progressively decline with age, resulting in increased
risk of orthostatic hypotension
• Reduced adrenergic responsiveness by the aged heart
diminishes baroreflex-mediated cardioacceleration in
response to hypotension
• Decrease in cerebral blood flow by 20%
• Cerebral autoregulation process impaired in chronic
hypertension
Clinical Implications
• Postprandial hypotension: Decline in blood
pressure after a meal is prevalent among older
persons
• Increased risk of orthostatic and postprandial
hypotension with medications, e.g. nitrates,
diuretics, antihypertensive meds
• Older patients vulnerable to cerebral ischemia
and syncope
Aging and Volume Regulation
Ms. K., 25 years old
Mrs. L., 80 years old
• Fluid deprivation for 72
hours due to sore throat
(strep plus mononucleosis)
• Sodium: No change
• BUN: No change
• Serum Creatinine: No change
• Mild hypotension with sinus
tachycardia of 130
• Fluid deprivation for 24 hours
(made NPO by an intern, no
IV fluids ordered)
• Sodium: 146 – 150
• BUN: 32 - 40
• Serum Creatinine: No change
• Cardio-vascular changes:
hypotension with sinus
tachycardia of 100
Which of the following statements about
age-related changes in sodium and water
homeostasis is not true?
A. There is impaired conservation of Na and
water
B. Hypernatremia may occur without clinical
signs of dehydration
C. Atrial natriuretic peptide (ANP) levels are
decreased
D. There is decrease in renal response to ANP
Clinical Implications
• Predisposition to Dehydration
– Decrease in total body water as a percentage of body weight
– Decreased thirst drive
– Decreased antidiuretic hormone (ADH) response to
hypovolemia
– Decreased maximum urinary concentration
– Impaired access to water due to physical or cognitive
disorders
• Hyponatremia & CHF
– Decreased ability to excrete free water load leading to
hyponatremia and fluid overload
Aging and Thermoregulation
• Basal heat production decreases by 20% from
age 30 years to age 70 years due to active
muscle loss
• With age, the ability to regulate body
temperature and to adapt to different thermal
environments declines
• Elderly are more prone to hyper- and
hypothermia
Mrs. S is an 88-year-old woman who lives alone.
She has history of osteoarthritis of her hips and
knees. One night while going to the bathroom,
she fell. Unable to get up or call for help, Mrs. S
lay on the bathroom floor until her daughter
found her the next day and called an ambulance
to bring her to the ER. She does not complain
of pain. On examination, she is lethargic and
somewhat confused. Her skin is cold and pale.
BP is 110/60, pulse 60/min., rectal temp 95 F.
X-rays reveal no fracture.
What age-related changes make her more
vulnerable to develop hypothermia?
A. Decreased production of thyroid hormone
B. Impaired blood redistribution from splanchnic
circulation
C. Impaired skin vasodilation response
D. Reduced muscle activity and less shivering
E. Decrease in basal metabolic rate
Hypothermia: Risk Factors
• Reduced muscle activity and less shivering
• Impaired vasoconstrictor response to cooling
by skin arterioles, which results in impaired
ability to conserve heat
• Reduced meal-induced thermogenesis
• Delayed perception of being cold
• Difficulty in discriminating temperature
differences
An 80 year old female is found unresponsive in
her apartment on a hot summer day. The
apartment does not have air-conditioning. She
has history of mild dementia, CHF, and
Parkinson’s disease. Her medications include
enalapril, furosemide, and levodopa/carbidopa.
In the emergency room, her BP is 85/50, pulse
100/min, and rectal temp is 105 F. Her skin is
hot and dry.
What age-related changes predispose an elderly
person to heat stroke and its consequences?
A.
B.
C.
D.
E.
Reduced muscle activity
Increased threshold to initiate sweating
Impaired vasoconstrictor response
Impaired ability to conserve heat
Increased output of eccrine sweat glands
Hyperthermia: Risk Factors
• Impaired skin vasodilatation response and impaired
blood flow redistribution from splanchnic and renal
circulations
• Decreased thirst
• Increased threshold temperature to initiate sweating
• Decreased output of eccrine sweat glands
• Drugs that impair the response to heat (such as
anticholinergic agents [hypohydrosis], diuretics
[hypovolemia], and ß-blockers [impaired cardiovascular
responsiveness]) increase the risk of heat stroke
Fever Response In The Elderly
• The ability to raise body temperature (generate fever
response) in response to pyrogens (bacterial
endotoxins) is blunted with age
• Up to 25% of older persons with sepsis do not
exhibit a febrile reaction
• Another definition of fever is a temperature increase
of > 2°F (1.1°C) over baseline (if a baseline
temperature is available)
– This definition has a sensitivity of 82.5% and specificity of
89.9% in the institutionalized older population
Which of the following is not true about
age-related cardiac changes?
A.
B.
C.
D.
Resting cardiac output unchanged
Ejection fraction reduced
Early diastolic filling reduced
End diastolic filling increased
Cardiovascular: Structure
Age-associated change
Consequence
↓ compliance of arterial tree
↑ after load on left ventricle and
LVH
↑ Systolic and pulse pressure
Myocardial cell hypertrophy, ↑
interstitial fibrosis, drop out of cardiac
myocytes
Slowing of ventricular relaxation,
↓ LV compliance, ↑ contribution
of atrial contraction to LV end
diastolic volume
Apoptosis of S-A pacemaker cells,
fibrosis and loss of his bundle cells
Slower intrinsic heart rate, varying
degrees of heart block
Cardiovascular: Structure (cont’d)
Age-associated change
Decreased responsiveness to beta
adrenergic stimulation and reactivity to
baroreceptors and chemoreceptors
Consequence
↑ circulating catecholamines
Fibrosis and calcification of heart valves Aortic valve sclerosis and stenosis
Source: The Merck Manual of Geriatrics, 3rd Edition, edited by Mark H. Beers, and Robert Berkow. Copyright 2000 by
Merck & Co., Inc., Whitehouse Station, NJ.
The early diastolic left ventricular filling rate progressively slows
after age 20, so that by age 80, the rate is reduced by up to 50%
Cardiovascular Physiology
•
•
•
•
•
↓ maximal heart rate
↓ maximal cardiac output at exercise
↓ maximal aerobic capacity
↓ cardiovascular reserve
↓ threshold for congestive heart failure and
atrial fibrillation
Clinical Implications
• Systolic HTN and widened pulse pressure are risk factors
for stroke, renal failure, and heart disease
• Age is the strongest predictor of mortality following
Acute MI
– Diagnosis more difficult due to atypical presentation
• Diastolic heart failure (EF ≥ 50%) accounts for as many
as 50% of CHF patients over age 65
• Atrial fibrillation becomes more of a physiologic burden
to the old heart because of age-related slowing of
diastolic filling due to LV stiffness and greater
dependence for adequate filling on atrial contraction
An 82 year old female presents with increasing shortness
of breath and fatigue for the last few days. She has a
history of hypertension, diabetes mellitus type 2, and
osteoarthritis of the knees. Her medications include
glyburide 5 mg daily, hydrochlorothiazide 25 mg daily,
lisinopril 10 mg daily, and Ibuprofen 200 mg once daily
as needed. BP is 110/70, resp. 20/minute, pulse is
irregular. Lungs reveal bibasilar crackles and there is
trace pedal edema. PaO2 on room air is 65. EKG
reveals
Which age-related physiologic change makes her
more vulnerable to develop symptoms of CHF?
A. Decline in renal function
B. Hypoxia
C. Increase in atrial natriuretic peptide (ANP)
levels
D. Increase in BP
E. Tachycardia and loss of atrial kick
Aging Respiratory System
• Calcification of bronchial and costal cartilage
Stiffness of chest walls
Work of breathing
• Enlargement of alveolar ducts
Alveolar surface area
• Decreased lung elasticity and elastic recoil
• Lower respiratory muscle strength and endurance
• Decrease in cough and mucociliary clearance
Effects of Aging on Lung Function
• Lower maximum expiratory flows: FEV1, FEV1/FEV loss
of approximately 15-30cc/year in FEV1 from the peak
achieved at age 25-30 years
• Increased FRC and RV, lower VC, but stable TLC
• PaO2 declines linearly with aging until age 75, at which time
it stabilizes at about 80 mm Hg in healthy nonsmokers.
– This gradual decline is mostly attributable to V/Q mismatch caused
by age-related collapse of peripheral airways, leading to shunting of
blood through nonventilated alveoli. PaO2 at any age can be
roughly estimated by the equation PaO2 = 100 - (0.3 x age)
Effects of Aging on Lung Function
• Lower diffusing capacity
• Reduced respiratory drive for hypoxia and
hypercarbia
Clinical Implications
• Higher risk for developing respiratory failure in response to
an acute illness
• Non-pulmonary conditions such as congestive heart failure,
cerebrovascular accidents, and nutritional disorders can
also precipitate respiratory failure in the elderly
• The complaint of dyspnea must be taken seriously because,
compared with younger adults, older adults may not
develop this symptom until they are at a later stage in their
illness
• The elderly have a 5-10 fold increased risk of pneumonia as
compared to younger adults and are much more likely to
die from this disease than their younger counterparts
An 80 year old white male complains of mild shortness
of breath on exertion. He denies any chest pain,
wheezing, or cough. There is no history of hypertension
or CAD. He denies a history of smoking. On
examination, his lungs are clear with no crackles or
wheezing. X-ray of the chest and electrocardiogram
reveal normal findings. Patient is referred for pulmonary
function testing.
Which of the following describes expected agerelated changes in pulmonary function?
A. Decreased total lung capacity, decreased FEV1,
decreased residual volume
B. Increased total lung capacity, decreased FEV1
and decreased residual volume
C. Increased total lung capacity, decreased FEV1
and increased residual volume
D. Stable total lung capacity, decreased vital capacity,
decreased residual volume
E. Stable total lung capacity, decreased vital capacity,
increased residual volume
Renal System
• General decline in glomerular filtration rate by about 1
ml/year after 40
– 30% showed no deterioration (BLSA)
• Progressive decline in ability to excrete a concentrated or a
dilute urine
• Delayed or slowed response to sodium deprivation or a
sodium load
• Decreased levels of renin and aldosterone
• Increased dependence on renal prostaglandins to maintain
perfusion
• Decreased Vitamin D activation
Lindeman RD, Tobin J, Shock NW. J Am Geriatr Soc 1985;33(4):278-285.
Clinical Implications
• Creatinine clearance should always be calculated before
starting or increasing doses of a medication cleared by
the kidney
• Serum creatinine values are not reliable estimates of renal
function
• Nephrotoxic drugs should be avoided whenever possible
• Use of drugs that inhibit the renin-angiotensinaldosterone system (such as ACE inhibitors and
angiotensin and aldosterone receptor antagonists) can
contribute to hyperkalemia in older adults.
• Acute renal failure develops faster, with relatively minor
stressors, and carries a higher mortality
Calculating Creatinine Clearance
• Estimate by Cockcroft - Gault formula
(140 - age [yr]) x weight [kg]
--------------------------------------- x 0.85 (if patient is female)
72 x serum cr (mg/dL)
• MDRD ( modification of diet in renal disease)
170 x [Scr]-0.999 x [age]-0.0176 x [0.762 if patient is female; 1.180
if patient is black] x [SUN]-0.0170 x [albumin]+0.318
Which aspect of renal function is relatively
maintained with aging ?
A.
B.
C.
D.
E.
Ability to excrete acid load
Concentrating capacity
Diluting capacity
Erythropoietin production
Metabolism of parathyroid hormone
Mrs. S is a 70 year old retired school teacher,
who comes for a routine follow-up of her
blood pressure. During her visit, she
comments that she is concerned about her
memory. She notes that she's having more
difficulty remembering the names of
individuals she knows when she meets them.
She also complains of misplacing her keys .
Which of the following is least
consistent with normal aging?
A. Delayed retrieval
B. Decreased speed of processing
C. Forgetfulness that interferes with
independent living
D. Decreased multitasking performance
Aging Nervous System
Memory
• Immediate memory (sensory)
– No change
• Short term memory
– No change
– It is widely believed that one type of memory, called working memory, is
most affected by age. Working memory is the retention of information
that must be manipulated or transformed in some way.
• Long-term memory
– Late in the aging process, “semantic memory” declines, referring to
memories of facts or concepts. “Procedural memory” remains
unaffected.
Aging Nervous System
Intellect
• Crystallized intelligence (learning and experience stable
or improves with age)
• Fluid intelligence (problem-solving with novel material
requiring complex relations) declines rapidly after
adolescence
Processing speed
• Mental processing and reaction time become slower
with age
Aging Nervous System
Language
• Vocabulary - increases into 50s and 60s - errors or
failures in naming occur with increasing frequency,
beginning in mid-life; encoding strategies very helpful
• Syntactic skills - combine words in meaningful sequence
- no decline with age
Attention
• No change
Executive function
• Ability to conceptualize, plan does not change
Age Associated Memory Impairment
(AAMI)
• Decreased multitasking performance
• Decreased processing speed
• Impaired or delayed retrieval
Clinical manifestations
• Retrieving the name of a vague acquaintance
• Remembering every item to buy from a grocery store
without a list
• Recalling where an object was placed
Vision and Hearing
Vision
• Decline in accommodation (presbyopia), low-contrast
acuity, glare tolerance, adaptation, and color
discrimination. These changes affect reading, balance,
and driving.
Hearing
• High frequency sensory neural hearing loss
(presbycussis). Consequences include difficulty in
localizing sound and understanding speech.
Improving Communication
•
•
•
•
•
Provide a respectful and supportive environment
Allow sufficient time for the older patient to process
new information.
Speak slowly facing the patient. Do not speak louder
Provide written materials to complement oral
instructions.
Use repetition to ensure that instructions were clear
and that your communication has been effective.
Laboratory Values In Old Age
UNCHANGED
Liver function tests
Coagulation tests
Arterial blood Gases
pH
pCO2
Serum electrolytes
Serum creatinine
Calcium, phosphorus
Total protein
T4, TSH
Complete Blood Count
DECREASED
Serum albumin
INCREASED
Alkaline phosphatase
Creatinine clearance
Sed rate
paO2
Post-prandial blood sugar
Total cholesterol
Triglycerides
Interaction of Aging and Hospitalization
Age-Related Changes
Contribution of Hospitalization
Effects
Consequences
Loss of muscle mass and
strength
Bed rest, restraints, tethers
Deconditioning
Dependency, falls
Baroreceptor insensitivity,
less thirst drive, less body
water
Inaccessibility to fluids, diseaseassociated dehydration
Postural hypotension
Falls & related injuries,
dizziness, syncope
Lower maximum expiratory
flows, reduced paO2
Reduced ventilation from bed rest
Hypoxia, respiratory
failure
Delirium, increased
mortality from
pneumonia
Reduced bladder capacity,
prostate enlargement, pelvic
floor relaxation
Barriers, unfamiliar environment
Tendency to
incontinence
Functional incontinence,
catheters
Fragile skin
Reduction in vascularity
Bed rest, shearing, incontinence
Increased pressure on
buttocks, heals
Pressure sores
Vision & hearing loss
Sensory deprivation (e.g., glasses,
hearing aid)
Sensory overstimulation (e.g., sleep
deprivation, noisy environment)
Confusion
Delirium
Restraints
Longer length of stay
Psychotropic drugs
Modified from: Creditor MC. Hazards of hospitalization of the elderly. Ann Int Med 1993;118(3):219-223
Conclusions
• Aging is associated with reduced functional reserve and
a compromised ability to cope with stressors
• Elderly are a heterogeneous group and there is great
individual variability
• Always think of interventions which may be useful in
helping patients cope with and/or overcome some of
the changes brought by normal aging
• Start building your reserves NOW