adv. princip: elderly anesthesia Flashcards
1
Q
- what is geriatric?
2. what percent of popluation (and in millions) is this?
A
- geriatric is older than 65
2. 13% of US popuation or 50 million americans
2
Q
- what decline in organ function does a 70 y/o have compared to a 30 y/o
- why dont elderly respond well to trauma, illness, anesthesia etc
- what systems change in elderly (in regards to anesthesia)?
A
- Decline in organ function (70 y/o has 40% decline in organ function vs 30 y/o)
- decreased margin of reserve/ decreased compensation ability
- cardiac, pulmonary, gI, GU/renal, autonomic system, nervous system in general
3
Q
cardiovascular changes in the elderly-name them in regards to:
- Left ventricle
- PVR/ blood pressure, C.O.
- vessel elasticity
- beta adrenergic responses
- arterial compliance (and what changes cause)
- how they maintain C.O.
- what about atrial kick?
- CHF (what increases it?)
- Vagal tone changes
- SA node changes
- common arrhythmias
A
- increase in LV thickness, leads to LVH
- systemic hypertension is common-PVR increases, C.O. decreases
- decreased elasticity of tunica media from fibrosisin periphry and coronary vessels= tighter/ less perfusion/ htn
- blunted beta adrenergic responses ( dont compensate with HR or contractility to position changes= orthostatic hypoTN
- reduced arterial compliance= increased afterload, increased systolic BP and LVH
- more reliant on increased end diastolic volume than increase in HR to increase C.O.
- higher reliance on atrial kick (which is 20% of left ventric end diastolic vol.).
- prone to CHF when given myocardial depressants (prop) and when hypotensive
- increased vagal tone and decresased sensitivity to adrenergic receptors leads to decreased HR (max HR declines 1 bpm by age 50).
- fibrosis of conduction system leads to loss of SA node function ( arrhythmias more common)
- Most prone to A-fib
4
Q
autonomic nervous system:
- regarding SNS, PNS
- Beta adrenergic receptor changes
- what do beta adrenergic changes cause?
A
- SNS is increased ; PNS is decreased
- down regulation of B adrenergic receptor
- causes compromised compensation to abrupt changes in IV fluids, pressure ventilation, position changes, compromised thermoregulation and baroreceptor
5
Q
diminished cardiac reserve in elderly is seen as what during induction?
A
exaggerated drop in blood pressure
6
Q
- circulatory changes do what in regards to iv induction?
- what might this cause one to do, causing what?
- circulatory changes with inhaled anesthetics?
- what does this cause?
A
- circulatory changes cause delay in onset of iv medications (delay in distribution is bad for iv meds)
- might cause one to give more=overdose
- circulatory changes decrease uptake of inhaled anesthetics =quicker onset (delay in distribution is good for inhaled gas)
- decreased mac (mac decreases 4-6% for every decade past age 40)
7
Q
PULMONARY changes with age:
- lung elasticity
- gas exchange
- residual volume (RV) and closing capacity- changes lead to what?
- total lung capacity (TLC) changes; what causes this?
- Pulmonary capillary blood volume
- paO2 (what is the formula)?
- alveolar-arterial difference (how is it different at 20 y/o and 70 y/o)
- arterial partial pressure
A
- lung elasticity decreases, alveoli overdistend and small airways collapse
- decreased gas exchange effeciecy
- increased residual volume and closing capacity which leads to VQ mismatch (closing volume is greater than FRC), tidal volume is distributed to less perfused areas of lungs
- Total lung capacity decreases by 10% by age 70 d/t loss of height, thoracic cage stiffness, anterior rotation of ribs and sternum
- reduction of pulmonary capillary lung volume-
- PaO2 declines based on formula PaO2=100-(0.4 x age(yrs) x mmHg)
- alveolar-arterial difference increases from 8mmHg at 20 to 20 mmHg at 70.
- arerial partial pressure decreases 0.5 mmhg per year after age 20
8
Q
- elderly require (more or less) oxygen post procedure? therefore, what conditions are common?
- what are airway reflex changes in elderly?
- when will airway issues be noticed in the elderly (in or or pacu)?
- when in doubt or elderly has major surgery or resp disease, what should you do as far as extubation?
A
- elderly require more oxygen during and after surgery, hypoxia and hypercarbia are common
- loss of protective reflexes in elderly increase change of aspiration (common occurence)
- elderly more apt to have resp impairment in pacu (usually narcotic related)
- elderly with high risk should stay intubated in pacu or phase 1
9
Q
GASTRIC/HEPATIC
- Hepatic blood flow changes
- albumin and cholinesterase production changes
- changes in liver mass
- plasma clearance of drugs changes, this leads to…
A
- decreased hepatic blood flow (probably due to decreased cardiac output)
- albumin production and cholinesterase synthesis decrease, but hepatocellular function only changes slightly
- decreased liver mass
- decreased plasma clearance of liver metabolized drugs leads to prolonged drug effects of anesthetics, NDMRs, and some narcotics (morphine, dilaudid, demorol).(fentanyl is metabolized in lungs mostly).
10
Q
in summary, aging alters what when it comes to drugs?
A
pharmakokinetics (drug absorption, tissue distrubution, metabolism and elimination) and pharmakodynamics (drug quantity vs effect)
11
Q
Pharmakokinetics:
- decrease in albumin causes what in regards to drugs?
- decreased blood plasme causes what?
- increase in body fat percentage causes what?
- decreased renal and hepatic blood flow causes what?
A
- decreased protein binding which allows more of the drug to be unbound (increased plasma levels) and cross the BBB
- decreased blood plasma = higher initial plasma concentration of drug
- increased total body lipid allows for more storage which prolongs half life
- decreased renal and hepatic blood flow slows metabolism and elimination
12
Q
pharmakodynamics: reduction of brain mass, brain blood flow, decreased axons, neurons and neurotransmitter cause what in regards to : -mac - barbiturate doses -half life of narcotics- -NDMR effect
A
- causes reduced mac (4% foe each decade past 40 yrs)
- decreased induction doses of barbiturates by 30-40%
- half life and duration of action of narcotics
- NDMR have prolonged effect
13
Q
RENAL:
- what are changes in the GFR (%)
- what are changes in renal vascular flow (%)
- what are changes in renal vascular bed
A
- GFR rate decreases 6-8% per decade (d/t reduced plasma flow d/t reduced plasma flow).
- Renal blood flow decreases 1-2% per year after 25 yrs old (has decreased by 40-50% by age 65).
- decreased size of renal vascular bed
14
Q
what NDMR is most likely to hang around in the elderly (metabolized mostly by liver)
A
Pavulon (pancuronium)
15
Q
- what happens to the nervous system of the elderly?
2. how does that affect pharmakodynamics (in terms of onset and potency)?
A
- loss of neurons, decreased conduction velocity, decreased # of fibers in spinal cord tracts
- medications deal with impulses, which are decreased, therefore medications will work slower, but when they finally do kick in, the elderly need less of a dosage.
