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Geriatric — Frailty, POCD, Drug Clearance

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Special Populations — Geriatric · 9 min read

Reduced MAC, reduced clearance, frailty drives outcomes, POCD prevention bundle. Geriatric anesthesia is its own subspecialty.

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Apply frailty screening tools.
Adjust anesthetic plan for the frail.
Prevent postop delirium + cognitive decline.
Recognize age-specific pharmacology changes.

MAC age curve + induction dose reduction

MAC decreases ~6% per decade after age 40. Sevoflurane MAC: ~2.0% at age 30~1.5% at age 80~1.3% at age 90. Same trend for all volatile agents.

Reduce induction doses 25-50% in patients >80 (propofol 1-1.5 mg/kg instead of 2-2.5; etomidate 0.15-0.2 mg/kg instead of 0.3).

Watch hemodynamics carefully — vasodilation + cardiac depression are exaggerated.

Comorbidity + frailty further reduce anesthetic requirement beyond age alone.

Use lowest effective MAC + opioid-sparing strategies — high MAC causes hypotension that worsens postop delirium.

Geriatric physiology and anesthetic considerations: decreased lean mass, organ reserve, GFR, hepatic clearance; reduced MAC (~6%/decade after 40); increased sensitivity to opioids, sedatives; risk of postop delirium.

Pharmacokinetic + pharmacodynamic shifts

KeyHepatic blood flow decreases 20-40% by age 80 reduced clearance of high-extraction drugs (propofol, morphine, fentanyl, lidocaine).

Renal function declines ~1 mL/min/year after 30 renally-cleared drugs accumulate (cisatracurium hofmann-eliminated is safest NMB choice; morphine glucuronide accumulation; aminoglycosides; digoxin).

Altered Vd

reduced lean mass + total body water
increased fat water-soluble drugs concentrated initially
fat-soluble drugs prolonged distribution

Reduced plasma albumin more free drug.

Increased pharmacodynamic sensitivity of CNS to opioids + sedatives at any given plasma level.

NET: prolonged effect of most anesthetics + slower emergence — titrate carefully, plan for longer washout.

Age-related physiologic changes in the elderly: decreased cardiac reserve, stiff lungs/lower FRC, reduced GFR, hepatic blood flow drop, smaller brain mass and altered pharmacodynamics increasing anesthetic sensitivity.

Frailty as outcome predictor

Fried criteria (≥3 of 5 = frail, 1-2 = pre-frail): unintentional weight loss >10 lbs/yr, self-reported exhaustion, low physical activity, slow gait speed (<0.8 m/s), weak grip strength.

Clinical Frailty Scale (Rockwood CFS) 1-9: 1 = very fit 9 = terminally ill.

Frailty independently predicts postoperative morbidity, mortality, prolonged length of stay, non-home discharge, and 1-yr mortality — MORE PREDICTIVE THAN AGE OR ASA STATUS ALONE.

Use frailty assessment to inform

prehabilitation (3-4 weeks pre-op nutrition + exercise)
ICU bed planning
honest family discussion of expectations + goals of care
technique selection (regional + multimodal favored)
shared decision-making about whether to proceed with elective surgery

Frailty assessment in surgical patients: gait speed, grip strength, Fried phenotype, Clinical Frailty Scale; predicts postoperative morbidity, mortality, delirium, and prolonged recovery.

Postop delirium — recognize + prevent

KeyPostoperative delirium incidence in elderly: 10-40% depending on procedure.

Risk factors

age
baseline cognitive impairment
sensory deficits
depression
alcohol use
severe illness
multiple medications

Prevention bundle

AVOID benzodiazepines (worsen delirium — exception: alcohol/benzo withdrawal)

AVOID meperidine (normeperidine neurotoxicity)

AVOID tertiary anticholinergics (atropine, scopolamine, diphenhydramine, hydroxyzine — quaternary glycopyrrolate is fine because it doesn't cross BBB)

AVOID prolonged burst suppression on EEG

AVOID opioid excess (multimodal opioid-sparing)

MAINTAIN

MAP within 10-20% of baseline (especially in chronic HTN)
normoxia
normocarbia
normothermia
hydration

NON-PHARMACOLOGIC

bring glasses + hearing aids + dentures to PACU + floor
family presence
sleep-wake cycle preservation
mobility
dehydration prevention
frequent re-orientation

Perioperative delirium risk factors and prevention: age, baseline cognitive impairment, polypharmacy, sleep disruption; prevent with reorientation, sleep hygiene, avoiding deliriogenic drugs, multimodal opioid sparing.

POCD — postoperative cognitive dysfunction

KeyDistinguished from delirium: POCD is a SUBTLE persistent cognitive change (memory, executive function) detected by neuropsych testing at 1-3 months postop, NOT acute confusion.

Incidence in elderly major surgery 10-15% at 3 months.

Mechanism debated

neuroinflammation
anesthetic-mediated neurotoxicity
perioperative hypotension/hypoxia
underlying preclinical Alzheimer's pathology unmasked by stress

Risk factors overlap with delirium.

Prevention strategies overlap.

Patient counseling: discuss in pre-op consent for elderly major surgery so families understand the recovery may include some cognitive change that usually resolves over months.

Regional vs GA in elderly

KeyREGAIN trial (NEJM 2021): regional vs GA for hip fracture surgery — equivalent outcomes for delirium, mortality, length of stay, and ambulation.

Multiple meta-analyses confirm: technique choice does NOT independently predict delirium.

What matters more

avoid hypotension
multimodal opioid-sparing
minimize benzodiazepines
normoxia + normothermia

Many anesthesiologists prefer regional/spinal for hip fracture (good analgesia + opioid sparing + early mobility for sitting up next day), but the evidence supports either approach when delivered well.

If regional, use light or no sedation (no benzo, low-dose dexmedetomidine acceptable).

If GA, target adequate but not excessive depth (EEG-guided where available).

Specific drugs to use + avoid

USE

cisatracurium (Hofmann elimination — organ-independent)
dexmedetomidine (delirium-sparing in ICU + opioid-sparing)
acetaminophen (multimodal)
regional anesthesia

CAUTION

propofol (lower dose, slower titration, hypotension risk)
morphine (active metabolite accumulation in renal impairment)
gabapentinoids (significant sedation in elderly — start very low if used at all)

AVOID where possible

benzodiazepines (especially long-acting)
meperidine
anticholinergics with CNS penetration
NSAIDs in CKD/elderly (renal risk)
polypharmacy

Each new med should be questioned: does the elderly patient really need this?

Postoperative pain management - multimodal approach: combine opioids with acetaminophen, NSAIDs, gabapentinoids, ketamine, regional/neuraxial techniques; opioid-sparing reduces side effects and chronic pain risk.

Discharge + goals-of-care

KeyGeriatric postop trajectory is longer than for younger patients.

Anticipate slower recovery + greater need for skilled nursing or rehab over direct-home discharge.

Plan family + social support BEFORE surgery, not after — discharge planning starts pre-op.

Pre-op cognitive assessment (Mini-Cog, MoCA) helps predict postop trajectory.

Frailty assessment + prehabilitation (3-4 weeks of nutrition + exercise + correction of anemia/deficiencies) where feasible.

Goals-of-care discussion in pre-op clinic: align the surgery decision with the patient's quality-of-life priorities + life expectancy + functional baseline + tolerance for adverse outcomes.

Document the conversation.

Many elective surgeries that look reasonable on paper are not the right choice for a frail elderly patient when discussed honestly.

⚠ Common pitfalls

Routine benzodiazepine premedication — worsens delirium.
Standard volatile MAC — drops ~6% per decade after 40.
Aggressive crystalloid resuscitation — leads to interstitial overload in elderly.
Skipping the cognitive screen pre-op — baseline matters for postop comparison.

💎 Clinical pearls

Clinical Frailty Score ≥5 = significantly increased surgical risk.
Multi-component prehabilitation 2-4 weeks pre-op improves outcomes — exercise + nutrition + psychosocial.
Avoid burst suppression in elderly — associated with worse postop delirium.
ERAS pathways especially benefit elderly — fewer complications + faster recovery.

Recap

Clinical Frailty Score ≥5 = significantly increased surgical risk.
Multi-component prehabilitation 2-4 weeks pre-op improves outcomes — exercise + nutrition + psychosocial.
Avoid burst suppression in elderly — associated with worse postop delirium.
ERAS pathways especially benefit elderly — fewer complications + faster recovery.

Mark each section done to complete the module.