Physiology of Aging

Question 1

There is a _____ % decline in organ function per year after age 30.

Answer 1

1%

Question 2

What are some characteristics of the elderly population that are related to increased mortality in surgical cases?

Answer 2

> 80yo, male, low albumin, impaired ADLs, impaired functional status, ASA 3 or >, emergency surgery

Question 3

What are some effects of aging on body composition?

Answer 3

loss of skeletal muscle (lean body mass), increased % of body fat (decreased SQ fat), decreased skin elasticity, reduced skin and soft tissue perfusion, poor turgor; d\t collagen loss be careful with adhesives

Question 4

What are some reasons for increased incidence of post op shivering in the elderly?

Answer 4

increased O2 consumption (up to 400%), hypoxia, acidosis, cardiopulmonary compromise; these patients also have a low basal metabolic rate and could have hypothyroidism so PREVENT hypothermia

Question 5

Cardiac function declines by _____ % btw the ages of 20 and 80.

Answer 5

50%

Question 6

What are some cardiovascular changes seen in the elderly population?

Answer 6

peripheral vascular changes (increased wall thickness and diameter, stiffening of aorta and large arteries, decreased vasodilation, systemic HTN, decreased baroreceptor sensitivity), increased LV wall thickness (HTN), decreased compliance, thickening of aortic valve cusps, LVH, impaired pump function, reduced CO, prolonged circulation time, increased incidence of CAD, lower maximal HR, decreased catecholamine response

Question 7

While newborns rely on HR for adequate cardiovascular stability, the elderly population have a greater reliance on ________ and ________.

Answer 7

LVEDV and atrial contraction (atrial kick)

Question 8

What is the best indicator of postoperative functional status?

Answer 8

preoperative functional status (report of ADLs and METs)

Question 9

What are some ANS changes seen in the elderly?

Answer 9

diminished parasympathetic outflow and increased sympathetic activity; reduced responsiveness to beta adrenergic stimulation; compromised thermoregulation, decreased baroreceptor sensitivity, dehydration

Question 10

What are some respiratory changes in the elderly population?

Answer 10

15% reduction in alveolar surface by 70yo (decreased area for gas exchange d\t reduction of elastic tissue and increased collagen); increased alveolocapillary membrane thickness leading to a decline in PaO2; decreased alveolar compliance (V/Q mismatch, increased physiological shunt, decreased efficiency of O2 exchange)

Question 11

Estimate the expected PaO2 for an 80 yo.

Answer 11

100- (0.4 x age); ~68

Question 12

T/F? A decrease in FEV, FVC, TLC, diminished CNS response to hypoxia & hypercarbia, and increased closing volumes are all normal findings in the elderly patient.

Answer 12

True

Question 13

What are airway changes seen in the elderly population?

Answer 13

decreased laryngeal and pharyngeal response (decreased airway clearance and gag–aspiration), narrowed airway passages (increased WOB, more turbulent flow), edentulous, cervical arthritis (limited extension/flexion)

Question 14

What are renal changes seen in the elderly population?

Answer 14

renal atrophy (50% reduction in functioning nephrons by age 80— 1-1.5% per year decline in GFR), RBF decreases 1-2% per year after age 25 (by 65, RBF decreases 40-50%), impaired ability to concentrate urine and preserve H2O and Na (electrolyte abnormality, hypovolemia, dehydration)

Question 15

What are liver changes noted in the elderly population?

Answer 15

same crap…. reduced tissue mass, decreased hepatic BF, reduced filtration…. but few changes in hepatocellular function

Question 16

A serum albumin < than _____ g/dL is associated with malnutrition in the elderly.

Answer 16

<3

Question 17

Name some GI changes in the elderly.

Answer 17

decreased motility, increased gastric residual volume, dysfunction of sphincters (LES)—- possible RSI, avoid LMA, prophylactic antacids

Question 18

Name some endocrine change in the elderly.

Answer 18

atrophy of endocrine glands…. reduced hormone production (insulin, thyroxine, growth hormone, renin, aldosterone)…. increased postprandial blood glucose levels (decreased liberation of insulin in response to hyperglycemia, resistance to insulin effects)

Question 19

Name hematologic changes seen in the elderly.

Answer 19

diminished bone marrow function, decreased hematopoiesis (formation of blood cellular components), anemia— get baseline H&H, preop blood consent

Question 20

What are some CNS changes seen in the elderly?

Answer 20

decreased: brain mass (30% by 80), neuronal density, CMO2, CBF, neurotransmitter receptor sites, conduction velocity in peripheral nerves, synthesis of neurotransmitters, fibers in spinal cord tracts…. BUT structural changes in CNS are NOT automatically associated with decline in cognitive function

Question 21

Post op delirium in the elderly tend to manifest within ____ to ____ days post op in patients over the age of ______.

Answer 21

1-3 days; >70; DELIRIUM (drug use, electrolyte abnormality, lack of drugs, infection, reduced sensory input, intracranial problems, urinary retention, myocardial problems)

Question 22

Age impacts the circadian pattern of __________, _________, and _______ and can cause desynchronation or “internal phase drift”.

Answer 22

body temp, plasma cortisol, and sleep

Question 23

What is the concept of homeostenosis?

Answer 23

the idea that from maturity to senescence (the process of deterioration with age), diminishing physiologic reserves are available to meet challenges to homeostasis; leads to increased vulnerability to disease occurring with aging; endpoint of this process is frailty, where even the smallest challenge overwhelms the available reserves and results in disaster

Question 24

_______ is the state when physiologic reserves are maximally invoked just to maintain homeostasis and any challenge will cross some threshold.

Answer 24

frailty

Question 25

What happens to red cell lifespan, iron turnover, and blood volume with advanced age?

Answer 25

they are unchanged with age; however, bone marrow mass decreases and fat in the bone marrow increases with increasing age…. therefore functional reserves are reduced with age

Question 26

What happens to the total circulating white cells and platelets in the older person?

Answer 26

does not change in healthy older people, but function of several types of cells is reduced; # of platelets are unchanged…. but platelet responsiveness to a number of thrombotic stimulators is increased… results in a small but consistent decrease in bleeding time with age…. should be considered a procoagulant state….. overall age is an important risk factor for DVT

Question 27

What are some changes with the oropharynx in the elderly?

Answer 27

loss of esophageal muscle compliance results in increased resistance to flow across the upper esophageal sphincter…. up to 60% pts without dysphagia have abnormal transfer to the pharynx…. less effective mastication and decreased food clearance from the pharynx lead to increased risk of aspiration in older adults

Question 28

The “older” kidney is subject to the following: (T/F):

• decrease in creatinine clearance
• very little overall decline in GFR
• creatinine production decreases and tubular secretion of creatinine increases resulting in primarily stable serum creatinine overall
• without presence of complication… fluid and electrolyte homeostasis are maintained relatively well
• impairment in excreting acid load
• less likely to recover from insult

Answer 28

TRUE

Question 29

What are the changes in the elderly in regards to HR and response to catecholamines?

Answer 29

intrinsic HR decreases by five to six beats per minute each decade…. response to both parasympathetic antagonists (atropine) and beta adrenergic agonists (isoproterenol) is decreased in healthy older people; target maximum HR is calculated as 220-age…. heart rate variability, perhaps d\t decreased parasympathetic tone and decreased sympathetic responsiveness, also decreases with age

Question 30

What are some considerations for an RSI of an elderly patient?

Answer 30

medications used for RSI cause more pronounced hypopnea and hypotension in the elderly than in younger, healthy patients…. reduce dose of short-acting opioids used for pretreatment and induction agents by approx 30-50%… use standard dosing for neuromuscular blocking agents