Exam 3: Special Populations

Question 1

normal age-related changes that cause decreased organ reserve in older ppl

Answer 1

• ↓ fn or diminished size of organs
• ↓ liver
• ↓ brain size
  
  • maintain crystal memory (songs, language)
  • ↓ concrete memory
• cardiac changes
  
  • volume-dependent (can’t really contract much stronger or faster)
  • thicker LV
  • ↑ LVEDP
  • endogenously B-blocked
  • less able to ↑ HR - and thus BP
• lungs
  
  • stiffer + thickened alveoli - ↓ ventilation/perfusion matching

Question 2

PK changes in the elderly:

body water

lean body mass

body fat

serum albumin

kidney wt

hepatic blood flow

Answer 2

body water: ↓

lean body mass: ↓ - “losing muscle”

body fat: ↑

serum albumin: ↓

kidney wt: ↓

hepatic blood flow: ↓ (55-60%)

Question 3

define ELDERLY

Answer 3

>65 yrs old

Question 4

anesthetic considerations for elderly

Answer 4

• give them more time
• ↓ doses usually
• ↓ volatile anesthetic 4-6% per decade after 40 yrs of age
• brains are more sensitive to opioids
  
  • use a BIS monitor
  • even then the BIS might be low but the surgeon claims that you need a certain minimum dose for amnestic effects
• are more sensitive to anesthetics - 2/2 ↓ neuronal fn?
• might need additional monitoring for anesth depth (BIS)
• age-related dose reductions of IV meds
  
  • longer T1/2
  • 30% decreased dose / 10 yrs?
  • plasma drug []s right after administration tend to be higher in elderly
• CYP 450 fn maintained
• ↓ plasma esterase fn in men > women (longer action of succinylcholine!)

Question 5

pain control and the elderly

Answer 5

• might be hard bc if preexisting cogn. impairment
• fear of opioid-related SEs (dosage inversely related to age)
• regional anesthesia:
  
  • anatomic changes in epidural/SA spaces
  • ↓ diameter and # of myelinated fibers - ↓ rate of nerve impulses
  • increased permeability of dura, ↓ volume of CSF, also pachy calcifications (can lead to a patchy block)
  • occlusion of intervertebral foramina with fibrous CT
  • fixed dose/volume of LA - spread of block is higher in elderly (esp ↑ cephalad spread)
• lower tolerance of “experimental pain”

remember than uncontrolled pain can lead to confusion

Question 6

muscle relaxants and the elderly

Answer 6

• ↓d skeletal muscle mass!
  
  • give the same nondepolarizing doses as non-elderly tho
• onset of action is delayed - proliferation of nAChR’s - might need to increase dose but also increase dosing interval
• DOA is extended (metabolism/elim)
• antagonism remains unchanged
• ↓ PChE
  
  • males > females

Question 7

postop delirium

Answer 7

• one of the most common postop complic’s for older adults
• upsetting for pts/families, and can be harmful if unrecognized/untreated
• delirium can be prevented in up to 40% of cases
• fluctuating consciousness, perception - can show up 1-3 post-anesthesia, after a lucid period. wtf.
  
  • ​is a neuro-inflamm process, exacerbated by faulty BBB
• cognitive dysfunction - could make it blurrier (?)

Question 8

anesethesia preop review of meds

Answer 8

• d/c meds with potential for interactions, or ↑ surg risk
• ID meds that should be d/c’d according to Beer’s criteria (list of meds unsafe for older adults)
• continue meds if potential for withdrawal
• don’t start new BZ’s, ↓ dose if at risk for post-op delirium
• avoid meds with active metab’s (morphine, meperidine)
• careful with antihistamines or anticholinergics
• start meds that ↓ periop CV events - B-blockers, statins
• adjust renally cleared meds