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define the term geriatrics

refers to the study of the elderly
*many accept > 65 y/o as elderly


define octogenarian

person > or = 80 y/o


define nonagenarian

person > or = 90 y/o


define centenarian

person > or = 100 y/o


define supercentenarian

person > or = 110 y/o


what are the most frequent conditions in the elderly population?

-diagnosed arthritis (d/t yrs. of wear and tear on joints)
-all types of heart disease (CAD, myopathies, valve, etc.)
-any cancer (risk increases with age)
-DM (obesity; decreased pancreas efficiency)


what are some theories of aging?

-Free radicals (ROS) stress cell mitochondria and its enzymatic machinery of oxidative phosphorylation
-defective mitochondrial DNA impairs bioenergetics efficiency
-reduced cellular ability to scavenge by-products of aerobic metabolism
*progressive degenerative changes affect both structure and function of organism


what does increased intracellular free-radicals (ROS) lead to?

-damage to membranes, proteins, and genetic integrity
-> decreased antioxidant and scavenging capacity
-> oxidative stress
-> further increase in ROS


what else does damage to membranes, proteins, and genetic integrity d/t increased ROS lead to?

-decreased bioenergetics capacity
-> loss of tissue and organ functional reserve
-> increased susceptibility to disease, infection, and injury
-> increased probability of death


what does organ functional capacity determine?

whether a person is considered physiologically old or young
*young person with declining organ function can be considered physiologically old & vice versa
*chronological age is the person's actual number of years


what can influence alterations in a person's functional capacity?

-physical and mental activity levels
-co-morbid conditions
-social habits
-genetic background


describe functional reserve

the difference between basal and maximal organ capacity
*aging is associated with reduced functional reserve (maximal organ capacity declines with age; basal doesn't change much)
*endurance: "safety margin" allows individual to meet increased organ demands brought on by stress, disease, increased CO and CO2 production and excretion needs, poly-pharmacy and surgery
ex: basal HR 60, when running max 170; pt. with CHF max may be less than 120, leading to quicker ischemia


describe body composition of the elderly

-gender specific
-atrophy of brain, liver, and kidney
-decreased lean tissue mass (LTM)
-increased body fat
-decreased bone density in women
-decreased weight (men > women)
-total body water (TBW) decreases 10-20% d/t reduced LTM and skeletal muscle mass
-decreased intracellular water


describe changes in metabolism and thermoregulation in the elderly

-decreased LTM contributes to decline in basal metabolic rate (BMR)
-decreased heat production d/t reduced LTM: core temp reduced 2x more; direct relationship b/w re-warming time required w/ age; decreased SNS activity, thermoregulatory response


describe changes in carbohydrate metabolism

altered carbohydrate metabolic response
-decreased LTM limits storage of carbs
-reduced sensitivity of pancreatic islet cells to glucose
-increased insulin resistance d/t more fat


describe CV effects of aging

-ventricles and atria are thicker and stiffer
-decreased CO d/t decreased metabolic demands and decreased HR
-increased vagal tone ("physiological bradycardia")
-decreased beta adrenergic sensitivity (decreased response to beta blockers)
-dependent on atrial kick for ventricular filling (CO increased by LVEDV not by HR)
-decreased venous return with PPV or decreased SV with bleeding
-HTN, widening pulse pressure


how is CO best increased in the elderly?

-increasing LVEDV
*dependent on atrial kick to increase SV


what attributes to HTN and widening pulse pressure in elderly?

-aorta and larger vessels lose compliance and ability to store hydraulic energy
-greater afterload which impedes stroke volume ejection
-LV wall tension increase and LV mass increase


describe pulmonary effects of aging

-loss of elastic tissue recoil non-uniformly
-increased closing capacity (vol. small airways collapse)
-costo-chondral and thoracic joint stiffening further contributes to a reduction in lung compliance
-reduced alveolar surface area (15% less gas exchange)
-pulmonary gas exchange inefficiency
-decreased response to hypoxia and hypercarbia


what does the loss of elastic tissue recoil in the lungs lead to ?

-increased functional reserve capacity (FRC)
-increased residual volume (RV)
*elderly lungs expand but cant recoil to push all of volume back out


describe closing capacity

-volume small airways collapse
-small airways cannot be kept open by elastic forces
-closing volumes > volume of lung at rest end-exhalation


what contributes to pulmonary gas exchange insufficiency?

-ventilation perfusion mismatches: blood flow continues but not all being ventilated d/t decreased gas exchange; begins to mix with ventilated blood
-progressively worsening venous admixture


how does age effect PaO2?

PaO2 = 100 - (0.4 {age in yrs.} mmHg)


what further complicates the elderly's decreased response to hypoxia and hypercarbia?

anesthetic-induced hypoxic-pulmonary vasoconstriction (HPV) depression
-this mechanism helps by vasoconstriction to areas that are hypoxic to reduce blood flow to those areas and promote blood flow to areas with oxygenation
*anesthetics "numb" this mechanism


describe hepatic effects of aging

-reduced hepatic blood flow and portal perfusion
-organ function decreases by 1%/yr. after age 30
-liver mass decreases about 40% by age 80
-reduced nitrogen handling abilities
-reduced hepatic biotransformation and protein synthesis (decreased 1st pass metabolism)
*both increase free drug
-decreased CP450 enzymatic process


describe renal effects of aging

-decreased renal blood flow and renal mass
-decreased GFR, creatinine clearance
-unable to tolerate hypotension or decreased CO effects on metabolism
-renal Na+ handling less efficient
*susceptible to fluid overload if too much IVF or infused too rapidly


what is significant about serum creatinine levels in elderly?

-may be normal
*don't assume renal function is normal


what is the cause of less efficient renal reabsorption by the kidneys?

-decreased aldosterone leads to decreased Na+ conservation
-this leads to dehydration and hyponatremia


describe CNS effects of aging

-diminished reflexes
-decreased NT synthesis and loss of neurons
-decreased receptor density
-30% brain mass can be lost by year 80
-diminished NT conduction
-DA depleted
-reduction in cerebral blood flow
-reduced O2 consumption by neuronal tissue
-decreased cholinergic function
-increased incidence of post op delirium
-decreased sympathetic nervous system activity (HTN not d/t SNS but stiffer vessels)
-decreased thermoregulatory control mechanisms


what contributes to increased risk of post op delirium in the elderly?

-decreased cholinergic activity
-anticholinergic use