1. Geriatric Anesthesia
SC 李侑珊
石博元
VS 鄭雅蓉

2. Brief History 99 y/o female with No other systemic illness
Large bedsore for 5 months s/p debridement
Old right femoral fracture s/p Moore hemiarthroplasty on 1995
Osteoporosis
Dementia
No other systemic illness

3. CXR

4. Anesthesia record

5. Anesthesia record Agent Given dose Regular dose fentanyl 1 ml 2 ml
propofol
50 mg
80-90 mg
rocuronium
20 mg
40 mg
atropine
0.4 mg
Enlon
28 mg
32-40 mg

6. Age, Minimum Alveolar Anesthetic Concentration, and Minimum Alveolar Anesthetic Concentration-Awake
Eger, Edmond I II, MD
Anesth Analg Oct;93(4):947-53

8. Age related anatomic & Physiologic Changes
Geriatric Anesthesia
Age related anatomic & Physiologic Changes

9. Cardiovascular system and Autonomic Nervous System (1)
Decline in the responsiveness of β- receptors
- plasma catecholamine level unchanged
- decrease in beta-adrenergic receptors density(?)
- 75y/o vs. 25y/o, 20% decrease of maximal HR
Progressive replacement of supple, functional cardiac and vascular tissue (a. &v) by stiff, fibrotic material
- elevated afterload
- elevated systolic BP
- LV hypertrophy

10. Cardiovascular system and Autonomic Nervous System (2)
Decreased cardiac output
Decreased baroreceptor reflex
These factors render the elderly patients
less capable of defending their CO and BP
against the usual periop challenges.

11. Respiratory System (1) a decline in elasticity of the bony thorax
Increased residual volume
Decreased vital capacity
Increased dead space
a loss of muscle mass with weakening of the muscles of respiration
FEV1 decreases progressively with aging
ratio of FEV to TLC of the elderly decreases. (70% vs. >80%)

12. Respiratory system (2) a decrease in alveolar gas exchange surface
a decrease in central nervous system responsiveness
Ventilatory response to hypercapnia and hypoxia is blunted in the elderly (1/2 of 25y/o)
Thus, we need to increase FIO2 and tidal volume (watch out for oxygen toxicity and barotrauma)

13. Renal System Decreased renal mass, mainly in the cortex
Decreased renal blood flow
Due to glomerulosclerosis
RPF and GFR↓
3. Decreased tubular function
impaired fluid handling
decreased concentrating ability
decreased diluting capacity
impaired sodium handling
decreased drug excretion

14. Liver
There is a lack of correlation between structural and functional data concerning the aging liver, as a decline in organ volume does not necessarily reflect impaired metabolic function.
Reduced hepatic drug clearance is common in the elderly

15. Nervous System (1) Effects of aging on the nervous system include:
a general loss of neuronal substance
a decrease in the number of peripheral neurons
muscles innvervated by fewer axons, leading to possible denervation atrophy
conduction velocity is slightly affected by aging (slower)

16. Nervous System (2) increased sensitivity to opioid analgesics
decreased cell density, lower cerebral oxygen consumption and lower cerebral blood flow

17. Age related pharmacologic changes
Geriatric Anesthesia
Age related pharmacologic changes

18. Pharmacokinetic and pharmacodynamic differences in the elderly (1)
Protein binding:
Circulating level of serum protein (especially albumin) decreases in quantity
Qualitative change of serum protein reduce the binding effectiveness of the available protein.
This will lead to higher free drug levels and an enhanced delivery of the drug to the brain.

19. Pharmacokinetic and pharmacodynamic differences in the elderly (2)
Changes in body compartment
Age-related changes in body composition include a loss of skeletal muscle and an increase in percentage of body fat.
Increased availability of lipid storage sites, this will leads a gradual elution of these agents from the storage sites.

20. Pharmacokinetic and pharmacodynamic differences in the elderly (3)
Heaptic and renal function
Hepatic and renal function are reduced about 1% per year beyond 30.
Elimination half-life
Drug
Young adult
Old adult
Fentanyl
250min
925min
Diazepam
24hrs
72hrs
midazolam
2.8hrs
4.3hrs
vecuronium
16min
45min

21. Induction Agent (1) Thiopental
Administration of IV barbiturates produces the peripheral vasodilatation with a moderate BP decrease.
With a decreased baroreceptor reflex and increased vascular wall rigidity, the drug may cause a dangerous drop in BP.
In the elderly, elimination half-life is hrs(6-12 hrs in the young)
The thiopental dose requirement may decrease percent.

22. Induction Agent (2) Methohexial
Methohexial is rapid acting and has a higher hepatic clearance rate and shorter elimination time than thiopental.
More suitable for outpatient surgery.

23. Induction Agent (3) Propofol
Propofol produces greater decrease in systemic BP than thiopental .
Injecting the propofol slowly with sufficient time can minimize the effect of cardiovascular depression.
Studies show patients older than 80 exhibit less post-anesthetic mental impairment with propofol than other agents.
Induction: using mg/kg in the elderly (versus mg/kg in younger patients)

24. Muscle Relaxant (1)
Aging affects the neuromuscular junction in many ways:
The distance of the junction ↑
The number of ACh vesicle ↓
Receptors of ACh ↓
Sensitivity of ACh receptors —

25. Muscle Relaxant (2) Succinylcholine
This agent is metabolized by pseudocholinesterase which is not affected by the aging process.
The response of succinylcholine is unalterd with aging.

26. Muscle Relaxant (3) Non-depolarizing muscle relaxant
Long-acting agents:
Metocurine, pancuronium (renal)↑
Doxacurium, pipecuronium (renal) —
Intermediate-acting agents
Vecuronium, rocuronium ↑
Atracurium, cisatracurium (Hoffmann elimination)—

27. Muscle Relaxant (4)
The use of the intermediate-acting agent is prudent, because even the duration of one single dose of long-acting agent may be too prolonged for the planned surgery.
Fewer dose of non-depolarizing muscle relaxant will be required.

28. Opioids (1)
Increases in potency for alfentanil, fentanyl, and remifentanil were demonstrated in EEG studies.
A reduction in dosage in the elderly would be recommended.

29. Opioids (2) Fentanyl Alfentanil
Dose should be reduced to ½ to achieve the same effect.
Alfentanil
Same recommendation as fentanyl.

30. Volatile agents (1)
Ventilation perfusion mismatch will decrease the rate of action.
Decreased cardiac output will make the onset of the action more rapid.
Recovery from anesthesia with a volatile agent may be prolonged because of an increased volume of distribution (increased body fat).

31. Volatile agents (2)
The MAC of inhalational agents is reduced by 6% per decade of age over 40 years.
The lower lipid-solubility of sevoflurane and desflurane has advantage in the elderly:
More rapid control of anesthetic depth than higher lipid-solubility agents.
A faster emergence from anesthesia. (desflurane vs. isoflurane: 5.4 vs. 7 mins)

32. Summary

33. Anesthesia Record Agent Given dose Regular dose fentanyl 1 ml 2 ml
propofol
50 mg
80-90 mg
rocuronium
20 mg
40 mg
atropine
0.4 mg
Enlon
28 mg
32-40 mg

34. Thank you for your Attention