Unit 11 - Geriatrics Flashcards
most significant risk factor for developing cancer
old age
metabolic equivalent =
metabolic rate of a specific physical activity / metabolic rate at rest
1 MET = ____ mL O2/kg/min
3.5
a “yes” to what 2 questions indicates the patient is ok for surgery without the need for additional cardiac testing
- Can you walk up a flight of steps without stopping?
- Are you able to walk 4 blocks without stopping?
activities that = 1 MET
- self care activities
- working at computer
- walking 2 blocks slowly
activities that = 2 METs
- climbing a flight of stairs w/o stopping
- walking 1-2 blocks uphill
- light housework
- raking leaves
- gardening
approx oxygen consumption assoc with 4 METs
~1000 mL O2/min
approx oxygen consumption assoc with 4 METs
~1000 mL O2/min
METs assoc with poor, good, and outstanding functional capacity
1 MET = poor
4 METs = good
10 METs = outstanding
may be a better tool to predict functional status vs. METs
DSA - duke activity status index
how is frailty characterized
decreased reserve coupled with reduced resistance to stress (physiologic, physical, or psychosocial)
for every MET a patient can achieve, mortality decreases by:
11%
why do geriatric patients have an increased Vm
increased dead space necessitates an ↑ Vm to maintain a normal PaCo2
key resp changes in geriatric patients:
* Vm
* lung compliance
* lung elasticity
* chest wall compliance
* response to hypercarbia & hypoxia
* protective reflexes
* upper airway tone
- Vm & lung compliance increased
- the rest are decreased
why are geriatric patients at increased risk of respiratory failure
decreased PaO2, lung elasticity, and chest wall compliance all decrease pulmonary reserve
consequences of loss of elastic recoil in elderly pts
promotes small airway collapse
consequences of small airway collapse in geriatric patients
↑ dead space
↓ alveolar surface area
↑ V/Q mismatch
↑ A-a gradient
↓ PaO2
Altered lung volumes & capacities
what causes gas trapping in geriatric patients
The aged lung tissue has high compliance (it’s easy to inflate) BUT it has low elasticity (it’s harder for it to return to its original shape)
RV increases
what causes decreased chest wall compliance in geriatric pts
↑ Calcification of joints
↑ Diaphragmatic flattening
↑ A-P diameter
↓ Intervertebral disc height
↓ Respiratory muscle strength (↓ muscle mass)
↓ Lung elastic recoil
why are geriatric patients less responseive to hypercarbia & hypoxia
The chemoreceptors are less sensitive to changes is pH, PaCO2, and PaO2
why are geriatric patients at increased risk of aspiration
Reduced efficiency of cough and swallowing
* Greater stimulus is required to elicit the cough reflex
* ↑ Risk of aspiration
consequences of decreased upper airway tone in geriatric patients
Decreased respiratory muscle strength
↑ Risk of respiratory failure
↑ Risk of upper airway obstruction
Consider PAP or BiPAP in at-risk patients
why do geriatric patients have an increased FRC
- reduced elastic recoil allows lungs to overfill with gas
- increases RV and therefore FRC
RV = volime that remains in lugns after full exhalation
at what age does Closing capacity surpasses FRC in supine position
~45 yrs
at what age does CC surpass FRC when standing
~65 yrs
consequence of CC surpassing FRC in geriatric pt
small airways will collapse during tidal breathing
sets the stage for V/Q mismatch, increased anatomic dead space, and a reduction in PaO2
consequence of CC surpassing FRC in geriatric pt
small airways will collapse during tidal breathing
sets the stage for V/Q mismatch, increased anatomic dead space, and a reduction in PaO2
lung volumes that are increased in geriatric pts
RV
FRC
CC
lung volumes that are decreased in geriatric pts
VC
ERV
TLC in geriatric patients
unchanged
↑ RV + ↓ VC = 0 net change
what causes decreased VC in geriatric patients
- reduced lung elastic recoil
- increased chest wall stiffness
- weaker respiratory muscles
FRC is determined by the balance between what 2 things
- lung elastic recoil
- chest wall compliance
what causes chest wall stiffness in geriatric pts
- arthritic changes in costovertebral joints
- intercostal cartilage calcification
- atrophy of intercostal muscles
IRV in geriatric patients
decreased
↑ FRC reduces IRV
ERV in geriatric patients
decreased
↑ RV reduces ERV
ERV in geriatric patients
decreased
↑ RV reduces ERV
FEV & FEV1 in geriatric patients
decreased
most common coexisting disease in the elderly
cardiac disease
4 most common CV conditions in geriatric pts
- hypertension
- CAD
- CHF
- myocardial ischemia
2 best indicators of cardiac reserve
- Exercise tolerance
- ability to perform daily living activities
lung volumes that are decreased with age
VC
ERV
IRV
FEV
FEV1
lung volumes that are increased in geriatric pts
RV
FRC
CC
causes of increased BP in geriatric pts related to aging
- loss of elastin and increased collagin
- increased SVR and afterload
hypertrophy assoc with aging
concentric
increased LV thickness
hypertrophy assoc with aging
concentric
increased LV thickness
myocytes that die are not replaced - cells that remain increase in size
why do geriatric patients experience greater BP lability with induction or acute blood loss
vascular stiffness = decreased venous capacitance
why does diastolic dysfunction develop with age
impaired relaxation
what increases risk of A-fib in geriatric patients
Atria generate higher pressure to prime the non-compliant ventricle = atrial enlargement and risk of atrial fibrillation
why are geriatric patient at increased risk of dysrhythmias
- fibrosis of conduction system
- loss of SA node tissue
dysrhythmias geriatric pts are at increased risk for
- A-fib
- 1st degree block
- 2nd degree block
- sick sinus syndrome
BP changes in geriatric patients
- increased SBP, DBP, and PP
- Arterial stiffness increases SBP to a greater degree than DBP
why is aging assoc with reduced exercise tolerance and cardiac reserve
diminished ability to increase stroke volume
leads to decreased CO
HR changes in geriatric patients
- ↓ Responsiveness to catecholamines
- ↓ Response to hypotension, hypovolemia, and hypoxia
- Decrease in maximal HR
maximal HR calculation
220 - age
VTE risk in geriatric patients
increased - meet all 3 components of Virchow’s triad
- Venous stasis
- Hypercoagulability
- Endothelial dysfunction
response to catecholamines with age
decreased
why are geriatric pts at increased risk of orthostatic hypotension
decreased baroreceptor responsiveness
SNS and PNS tone in geriatric pts
SNS = increased
PNS = decreased
why is SNS tone increased in geriatric pts
Higher norepinephrine concentration in the plasma
This effect is blunted by reduced beta receptor sensitivity and reduced coupling with adenylate cyclase
beta receptors in geriatric population
reduced sensitivity d/t reduced receptor affinity & changes in signal transduction
change in MAC with age
decreases 6% every decade after age 40
consequences of decreased baroreceptor responsiveness in geriatric pts
increases risk of:
* Orthostatic hypotension
* Syncope
* Greater degree of hemodynamic compromise following sympathectomy
why are geriatric pts at increased risk of hypothermia
impaired thermoregulation
neurotransmitter activity changes in geriatric pts
Reduced activity of Ach, NE, DA, and GABA
Number of receptors may be reduced
neurotransmitter activity changes in geriatric pts
Reduced activity of Ach, NE, DA, and GABA
Number of receptors may be reduced
changes in peripheral nerves with age
- Reduced number of myelinated nerves
- Degeneration of nerves that remain reduces function
onset of postop delirium
early postop
most common periop CNS complication in geriatric pts
postop delirium
presentation of postop delirium
Disordered behavior, perception, memory, psychomotor skills
presentation of Postoperative Cognitive Dysfunction
Impaired concentration, comprehension, psychomotor skills
risk factors for postop delirium
DELIRIUM:
* Drugs (use rapidly metabolized drugs)
* Electrolyte imbalance
* Lack of drugs (withdrawal)
* Infection (UTI and respiratory)
* Reduced sensory input
* Intracranial dysfunction
* Urinary retention and fecal impaction
* Myocardial event, male gender
risk factors for postop cognitive dysfunction
Advanced age (most significant)
Pre-existing cognitive deficit
Cardiac surgery
Long duration of surgery
High ASA status
Low level of education
Anesthetic agents ???
treatment of postop delirium in geriatric pts
Treat underlying cause
Antipsychotics
Minimize polypharmacy
treatment of postop cognitive dysfunction
No specific treatment
Most cases are mild and tend to resolve after ~ 3 months
onset of postop cognitive dysfunction
weeks to months postop
changes in geriatric pts that affect neuraxial anesthesia
- ↓ CSF volume
- ↓ volume of epidural space
- ↓ diameter of dorsal & ventral nerve roots
- ↑ permeability of dura
peripheral changes in geriatric pts that affect neuraxial anesthesia
- ↓ inter Schwann cell distance
- ↓ conduction velocity
why are geriatric patients at risk for greater block height with epidural anesthesia
- decreased epidural space volume = greater LA spread
- dura is more permeable to LAs
why are geriatric pts at risk of greater block height with spinal anesthesia
- decreased CSF volume = greater spread
- dura more permeable to LAs
give ↓ dose
why are geriatric patients at increased risk of false negative response to epidural test dose
↓ myocardial sensitivity to catecholamines
why are geriatric pts predisposed to fluid overload and dehydration
impaired:
* sodium handling
* ability to concentrate urine
* capacity to dilute urine
serum Cr changes in elderly pts
no change
* GFR decreases with age (theoretically should ↑ serum Cr)
* Muscle mass also decreases with age (less Cr produced)
These 2 processes cancel each other out (net = unchanged Cr)
RBF changes with age
Decreases 10% per decade
what contributes to decreased renal mass in elderly
- decreased nephrons (cortex > > > medulla)
- loss of functioning glomeruli
why does ability to concentrate urine decrease with age
- Increased flow through medullary nephrons washes out solute, reducing osmolarity in this region
- ↓ Concentration gradient necessary to produce concentrated urine
reduced CrCl in elderly is a function of what 2 things
- ↓ Renal blood flow brings less creatinine to the nephron per unit time
- There are less nephrons to clear creatinine
most sensitive indicator of renal function and drug clearance in the elderly
CrCl
normal GFR in adult male
~125 mL/min
changes in GFR with age
decreases by 1 mL/min/year after age 40
why are elderly patients at increased risk of fluid overload
↓ GFR
less plasma delivered to nephrons per unit time
why do elderly patients have a reduced response to acid load
reduced capacity of the renal tubules to secrete ammonium
why does ability to conserve sodium decrease with age
decreased aldosterone sensitivity
alpha 1 glycoprotein levels in elderly
increased
Increased reservoir for basic drugs
Insignificant in clinical practice
alpha 1 glycoprotein levels in elderly
increased
Increased reservoir for basic drugs
Insignificant in clinical practice
alpha 1 glycoprotein levels in elderly
increased
Increased reservoir for basic drugs
Insignificant in clinical practice
albumin production level in elderly
decreased
Decreased reservoir for acidic drugs
Insignificant in clinical practice
hepatocellular function with age
no change
less total enzymes produced but they function normally
what causes decreased periop hepatic function
- Reduced as a function of ↓ blood flow & ↓ liver mass
- NOT because of impaired hepatocellular function
changes in first pass metabolism with age
decreased d/t reduced hepatic mass and liver blood flow
pseudocholinesterase production in elderly
decreased
Prolonged duration of succs and ester LAs
Men > women
consequences of decreased muscle mass in elderly
- ↓ Basal metabolic rate
- ↓ Total body water
- ↓ Blood volume
- ↓ Plasma volume
why do elderly patients have prolonged elimination of lipophilic drugs
↑ total body fat = ↑ increased Vd of lipophilic drugs
Vd for lipophilic and hydrophilic drugs in elderly
increased for lipophilic
decreased for hydrophilic
