Geriatric Anesthesia

SC 李侑珊 石博元VS 鄭雅蓉

Brief HistoryBrief History

99 y/o female with 99 y/o female with 1.1. Large bedsore for 5 months s/p debridemeLarge bedsore for 5 months s/p debrideme

ntnt2.2. Old right femoral fracture s/p Moore hemiaOld right femoral fracture s/p Moore hemia

rthroplasty on 1995rthroplasty on 19953.3. OsteoporosisOsteoporosis4.4. DementiaDementia

No other systemic illnessNo other systemic illness

CXRCXR

Anesthesia recordAnesthesia record

Anesthesia recordAnesthesia record

AgentAgent Given doseGiven dose Regular Regular dosedose

fentanylfentanyl 1 ml1 ml 2 ml2 ml

propofolpropofol 50 mg50 mg 80-90 mg80-90 mg

rocuroniumrocuronium 20 mg20 mg 40 mg40 mg

atropineatropine 0.4 mg0.4 mg 0.4 mg0.4 mg

EnlonEnlon 28 mg28 mg 32-40 mg32-40 mg

Age, Minimum Alveolar Anesthetic Age, Minimum Alveolar Anesthetic Concentration, and Minimum AlvConcentration, and Minimum Alveolar Anesthetic Concentration-eolar Anesthetic Concentration-

AwakeAwakeEger, Edmond I II, MDEger, Edmond I II, MD

Anesth Analg. 2001 Oct;93(4):947-53 Anesth Analg. 2001 Oct;93(4):947-53

Geriatric AnesthesiaGeriatric Anesthesia

Age related anatomic & Age related anatomic & Physiologic ChangesPhysiologic Changes

Cardiovascular system and Cardiovascular system and Autonomic Nervous Autonomic Nervous System (1)System (1)1.1. Decline in the responsiveness of Decline in the responsiveness of ββ- receptors- receptors

- plasma catecholamine level unchanged- plasma catecholamine level unchanged - decrease in beta-adrenergic receptors density(?)- decrease in beta-adrenergic receptors density(?) - 75y/o vs. 25y/o, 20% decrease of maximal HR - 75y/o vs. 25y/o, 20% decrease of maximal HR

2.2. Progressive replacement of supple, functional cProgressive replacement of supple, functional cardiac and vascular tissue (a. &v) by stiff, fibrotiardiac and vascular tissue (a. &v) by stiff, fibrotic materialc material-- elevated afterloadelevated afterload- elevated systolic BP- elevated systolic BP- LV hypertrophy- LV hypertrophy

Cardiovascular system and Cardiovascular system and Autonomic Nervous Autonomic Nervous System (2)System (2)3.3. Decreased cardiac outputDecreased cardiac output4.4. Decreased baroreceptor reflexDecreased baroreceptor reflex

These factors render the elderly patients These factors render the elderly patients less capable of defending their CO and BP less capable of defending their CO and BP against the usual periop challenges. against the usual periop challenges.

Respiratory System (1)Respiratory System (1)

1.1. a decline in elasticity of the bony a decline in elasticity of the bony thoraxthorax

• Increased residual volumeIncreased residual volume• Decreased vital capacityDecreased vital capacity• Increased dead spaceIncreased dead space

2.2. a loss of muscle mass with weakening a loss of muscle mass with weakening of the muscles of respirationof the muscles of respiration

• FEV1 decreases progressively with agingFEV1 decreases progressively with aging• ratio of FEV to TLC of the elderly decreases. ratio of FEV to TLC of the elderly decreases.

(70% vs. >80%)(70% vs. >80%)

Respiratory system (2)Respiratory system (2)

1.1. a decrease in alveolar gas exchange surfa decrease in alveolar gas exchange surfaceace

2.2. a decrease in central nervous system rea decrease in central nervous system responsivenesssponsiveness

• Ventilatory response to hypercapnia and hyVentilatory response to hypercapnia and hypoxia is blunted in the elderly (1/2 of 25y/o)poxia is blunted in the elderly (1/2 of 25y/o)

• Thus, we need to increase FIO2 and tidal voThus, we need to increase FIO2 and tidal volume (watch out for oxygen toxicity and barlume (watch out for oxygen toxicity and barotrauma)otrauma)

Renal SystemRenal System

1.1. Decreased renal mass, mainly in the cortDecreased renal mass, mainly in the cortexex

2.2. Decreased renal blood flowDecreased renal blood flow Due to glomerulosclerosisDue to glomerulosclerosis RPF and GFRRPF and GFR↓↓

3.3. Decreased tubular functionDecreased tubular function impaired fluid handlingimpaired fluid handling decreased concentrating abilitydecreased concentrating ability decreased diluting capacitydecreased diluting capacity impaired sodium handlingimpaired sodium handling decreased drug excretiondecreased drug excretion

LiverLiver

1.1. There is a lack of correlation There is a lack of correlation between structural and functional between structural and functional data concerning the aging liver, data concerning the aging liver, as a decline in organ volume as a decline in organ volume does not necessarily reflect does not necessarily reflect impaired metabolic function.impaired metabolic function.

2.2. Reduced hepatic drug clearance Reduced hepatic drug clearance is common in the elderly is common in the elderly

Nervous System (1)Nervous System (1)

Effects of aging on the nervous system Effects of aging on the nervous system include: include: a general loss of neuronal substancea general loss of neuronal substance a decrease in the number of peripheral nea decrease in the number of peripheral ne

uronsurons muscles innvervated by fewer axons, leadimuscles innvervated by fewer axons, leadi

ng to possible denervation atrophyng to possible denervation atrophy conduction velocity is slightly affected by conduction velocity is slightly affected by

aging (slower)aging (slower)

Nervous System (2)Nervous System (2)

increased sensitivity to opioid analgincreased sensitivity to opioid analgesicsesics

decreased cell density, lower cerebrdecreased cell density, lower cerebral oxygen consumption and lower ceal oxygen consumption and lower cerebral blood flowrebral blood flow

Geriatric AnesthesiaGeriatric Anesthesia

Age related pharmacologic Age related pharmacologic changeschanges

Pharmacokinetic and pharmacodynamic dPharmacokinetic and pharmacodynamic differences in the elderly (1)ifferences in the elderly (1)

Protein binding:Protein binding:– Circulating level of serum protein Circulating level of serum protein

(especially albumin) decreases in (especially albumin) decreases in quantityquantity

– Qualitative change of serum protein Qualitative change of serum protein reduce the binding effectiveness of the reduce the binding effectiveness of the available protein.available protein.

– This will lead to higher free drug levels This will lead to higher free drug levels and an enhanced delivery of the drug to and an enhanced delivery of the drug to the brain.the brain.

Pharmacokinetic and pharmacodynamiPharmacokinetic and pharmacodynamic differences in the elderly (2)c differences in the elderly (2)

Changes in body compartmentChanges in body compartment– Age-related changes in body Age-related changes in body

composition include a loss of skeletal composition include a loss of skeletal muscle and an increase in percentage of muscle and an increase in percentage of body fat.body fat.

– Increased availability of lipid storage Increased availability of lipid storage sites, this will leads a gradual elution of sites, this will leads a gradual elution of these agents from the storage sites.these agents from the storage sites.

Pharmacokinetic and pharmacodynPharmacokinetic and pharmacodynamic differences in the elderly (3)amic differences in the elderly (3)

Heaptic and renal functionHeaptic and renal function– Hepatic and renal function are reduced about Hepatic and renal function are reduced about

1% per year beyond 30.1% per year beyond 30.

Elimination half-lifeElimination half-life

DrugDrug Young adultYoung adult Old adultOld adult

FentanylFentanyl 250min250min 925min925min

DiazepamDiazepam 24hrs24hrs 72hrs72hrs

midazolammidazolam 2.8hrs2.8hrs 4.3hrs4.3hrs

vecuroniumvecuronium 16min16min 45min45min

Induction Agent (1)Induction Agent (1)

ThiopentalThiopental– Administration of IV barbiturates produces the Administration of IV barbiturates produces the

peripheral vasodilatation with a moderate BP peripheral vasodilatation with a moderate BP decrease.decrease.

– With a decreased baroreceptor reflex and incrWith a decreased baroreceptor reflex and increased vascular wall rigidity, the drug may causeased vascular wall rigidity, the drug may cause a dangerous drop in BP.e a dangerous drop in BP.

– In the elderly, elimination half-life is 13-25 hrsIn the elderly, elimination half-life is 13-25 hrs(6-12 hrs in the young)(6-12 hrs in the young)

– The thiopental dose requirement may decreasThe thiopental dose requirement may decrease 25-75 percent.e 25-75 percent.

Induction Agent (2)Induction Agent (2)

MethohexialMethohexial– Methohexial is rapid acting and has a hiMethohexial is rapid acting and has a hi

gher hepatic clearance rate and shorter gher hepatic clearance rate and shorter elimination time than thiopental.elimination time than thiopental.

– More suitable for outpatient surgery.More suitable for outpatient surgery.

Induction Agent (3)Induction Agent (3)

PropofolPropofol– Propofol produces greater decrease in Propofol produces greater decrease in

systemic BP than thiopental .systemic BP than thiopental .– Injecting the propofol slowly with sufficient Injecting the propofol slowly with sufficient

time can minimize the effect of time can minimize the effect of cardiovascular depression.cardiovascular depression.

– Studies show patients older than 80 exhibit Studies show patients older than 80 exhibit less post-anesthetic mental impairment less post-anesthetic mental impairment with propofol than other agents. with propofol than other agents.

– Induction: using 1.2-1.7 mg/kg in the elderly Induction: using 1.2-1.7 mg/kg in the elderly (versus 2.0-2.5 mg/kg in younger patients)(versus 2.0-2.5 mg/kg in younger patients)

Muscle Relaxant (1)Muscle Relaxant (1)

Aging affects the neuromuscular juAging affects the neuromuscular junction in many ways:nction in many ways:

1.1. The distance of the junction ↑The distance of the junction ↑2.2. The number of ACh vesicle ↓The number of ACh vesicle ↓3.3. Receptors of ACh ↓Receptors of ACh ↓4.4. Sensitivity of ACh receptors —Sensitivity of ACh receptors —

Muscle Relaxant (2)Muscle Relaxant (2)

SuccinylcholineSuccinylcholine– This agent is metabolized by pseudochoThis agent is metabolized by pseudocho

linesterase which is not affected by the linesterase which is not affected by the aging process.aging process.

– The response of succinylcholine is unaltThe response of succinylcholine is unalterd with aging.erd with aging.

Muscle Relaxant (3)Muscle Relaxant (3)

Non-depolarizing muscle relaxantNon-depolarizing muscle relaxant Long-acting agents:Long-acting agents:

– Metocurine, pancuronium (renal)↑Metocurine, pancuronium (renal)↑– Doxacurium, pipecuronium (renal) —Doxacurium, pipecuronium (renal) —

Intermediate-acting agentsIntermediate-acting agents– Vecuronium, rocuronium ↑Vecuronium, rocuronium ↑– Atracurium, cisatracurium (Hoffmann elAtracurium, cisatracurium (Hoffmann el

imination)— imination)—

Muscle Relaxant (4)Muscle Relaxant (4)

The use of the The use of the intermediate-intermediate-acting agentacting agent is prudent, is prudent, because even the duration of one because even the duration of one single dose of long-acting agent single dose of long-acting agent may be too prolonged for the may be too prolonged for the planned surgery.planned surgery.

Fewer doseFewer dose of non-depolarizing of non-depolarizing muscle relaxant will be required.muscle relaxant will be required.

Opioids (1)Opioids (1)

Increases in potency for alfentanil, feIncreases in potency for alfentanil, fentanyl, and remifentanil were demontanyl, and remifentanil were demonstrated in EEG studies.nstrated in EEG studies.

A reduction in dosage in the elderly A reduction in dosage in the elderly would be recommended.would be recommended.

Opioids (2)Opioids (2)

FentanylFentanyl– Dose should be reduced to ½ to achieve Dose should be reduced to ½ to achieve

the same effect.the same effect. AlfentanilAlfentanil

– Same recommendation as fentanyl.Same recommendation as fentanyl.

Volatile agents (1)Volatile agents (1)

Ventilation perfusion mismatch will Ventilation perfusion mismatch will decrease the rate of action.decrease the rate of action.

Decreased cardiac output will make Decreased cardiac output will make the onset of the action more rapid.the onset of the action more rapid.

Recovery from anesthesia with a Recovery from anesthesia with a volatile agent may be prolonged volatile agent may be prolonged because of an increased volume of because of an increased volume of distribution (increased body fat).distribution (increased body fat).

Volatile agents (2)Volatile agents (2)

The MAC of inhalational agents is reduceThe MAC of inhalational agents is reduced by 6% per decade of age over 40 years.d by 6% per decade of age over 40 years.

The lower lipid-solubility of sevoflurane aThe lower lipid-solubility of sevoflurane and desflurane has advantage in the elderlnd desflurane has advantage in the elderly:y:– More rapid control of anesthetic depth than higher liMore rapid control of anesthetic depth than higher li

pid-solubility agents.pid-solubility agents.– A faster emergence from anesthesia. (desflurane vs. A faster emergence from anesthesia. (desflurane vs.

isoflurane: 5.4 vs. 7 mins)isoflurane: 5.4 vs. 7 mins)

SummarySummary

Anesthesia RecordAnesthesia Record

AgentAgent Given doseGiven dose Regular Regular dosedose

fentanylfentanyl 1 ml1 ml 2 ml2 ml

propofolpropofol 50 mg50 mg 80-90 mg80-90 mg

rocuroniumrocuronium 20 mg20 mg 40 mg40 mg

atropineatropine 0.4 mg0.4 mg 0.4 mg0.4 mg

EnlonEnlon 28 mg28 mg 32-40 mg32-40 mg

Thank you for your Thank you for your AttentionAttention