Week 9 - Geriatric Anesthesia Flashcards
Does the following body composition components increase or decrease in the geriatric population?
- Skeletal muscle mass
- Percentage of body fat
- Total body water
- Oxygen consumption
- Heat production
- Skeletal muscle mass = decreases
- Percentage of body fat = increases
- Total body water = decreases
- Oxygen consumption = decreases
- Heat production = decreases
What physiologic changes occur in the central nervous system in the geriatric population?
- Loss of neural tissue (gradual decrease in brain size secondary to decrease in neuronal size)
- Decreased number of serotonin, acetylcholine, and dopamine receptors
- Reduction in cerebral blood flow
- Decline in memory, reasoning, perception
- Disturbed sleep/wake cycle
- Decreased parasympathetic nervous system tone
- Increased sympathetic neuronal activity
What physiologic changes occur in the cardiovascular system in the geriatric population?
- LV hypertrophy and decreased compliance (diastolic LV dysfunction)
- Increase in vascular rigidity (increase in SVR/SBP)
- Decreased compliance of venous vessels
- Desensitization of beta-adrenergic receptors (decrease in SV and CO, decreased max attainable HR, and exaggerated bradycardia following the admin of opioids)
How does the following pulmonary system components change in the geriatric population?
- Central airway size
- Small airway diameter
- Respiratory muscle strength
- Shape of chest
- Central airway size increases
- Small airway diameter decreases
- Respiratory muscle strength decreases
- Chest wall height decreases and the AP diameter increases
How does the following pulmonary system components change in the geriatric population?
- Chest wall compliance
- Respiratory center sensitivity
- Effectiveness of coughing and swallowing
- Functional alveolar surface area
- Chest wall compliance decreases (lung compliance increases)
- Respiratory center sensitivity decreases
- Effectiveness of coughing and swallowing decreases
- Functional alveolar surface area decreases
How does the following pulmonary system components change in the geriatric population?
- Diffusion capacity of carbon monoxide
- Peak inspiratory max and Peak expiratory max
- EVR and VC
- RV and FRC
- FVC, FEV1, FEV1/VC, and FEF at low lung volumes
- PaO2
- Closing capacity
- Diffusion capacity of carbon monoxide decreases
- Peak inspiratory max and Peak expiratory max decreases
- EVR and VC decreases
- RV and FRC increases with no change in TLC
- FVC, FEV1, FEV1/VC, and FEF at low lung volumes decrease
- PaO2 – increased A-a gradient and decreased PaO2
- Closing capacity is increased
Why is there a progressive decrease in vital lung capacity in the geriatric population?
Because of:
- the loss of elastic recoil of the lung
- increased chest wall stiffness
- decreased force generated by the respiratory muscles
What physiologic changes occur in the renal system in the geriatric population?
- Loss of tissue mass
- Decreased perfusion
- Decreased GFR
- Reduced ability to dilute and concentrate urine and conserve sodium
- Decreased drug clearance
*renal failure accounts for 20% of all periop deaths and acute renal failure in elderly pts in the postop period has a significant mortality rate
What physiologic changes occur in the hepatic system in the geriatric population?
- Decrease in tissue mass
- Decrease in blood flow
- Reductions in protein binding occurs potentially leading to an increase in free fraction of protein-bound drugs
- Decreased first-pass metabolism of some drugs
What should be included in the preop evaluation of a geriatric patient?
- Labs
- EKG
- Chest x-ray
- METs
- Hard of hearing?
- Dentures?
- Medications
- Nutrition status
*BMI of less than 18.5, serum albumin of less than 3.0 g/dL, and a weight loss of more than 10% in 6 months indicate severe nutritional risk
What are considered clinical risk factors when assessing a geriatric patient for surgery?
- Ischemic heart disease
- Compensated or prior heart failure
- Diabetes Mellitus
- Renal Insufficiency
- Cerebrovascular disease
What is frailty characterized by?
Decrease in physiologic reserve across multiple systems in excess of normal age-related decline in function
- estimated between 25-56% of elderly surgical pts
- independently associated with increased postop mortality rate, morbidity, and delirium
What are intra-op anesthetic concerns in the geriatric population?
- Volume of distribution for etomidate is reduced with aging (50% reduction in dose is recommended in pts 80 or older)
- Exaggerated hypotension with propofol
- Dose of midazolam should be reduced by 50% and repeat doses admin in increments of 0.5mg or less – AVOID long acting benzos
- Avoid prolonged periods of hypotension
- Careful fluid administration
How does MAC of inhaled anesthetics change in the geriatric population?
MAC decreases predictably by 6% every decade after age 20
What adjustments to volatile anesthetics do you need to make in elderly patients?
Decrease inspired concentration
