Geriatric Anesthesia

Dr.Mohamed Taha

People over 65 years of age are 3.5 times more likely to

have surgery.

Aging results in a progressive decline in the functional

reserve of all organs; the rate at which function

diminishes is highly variable between individuals.

Aging is a progressive physiologic process characterized

by :

1- Decreased end-organ reserve

2- Decreased functional capacity

3- Increasing imbalance of homeostatic mechanisms.

4- Increasing incidence of pathologic processes.

Pathophysiology Of Aging By System

Cardiovascular

Decreased arterial elasticity:

• Increased afterload

• Left ventricular hypertrophy

• Increased systolic blood pressure, mean arterial pressure, and pulse pressure

Autonomic imbalance:

• Increased vagal tone

• Decreased sensitivity of adrenergic receptors

• Decreased baroreceptor reflex

Fibrosis of the conducting system and loss of sinoatrial

node cells .

Sclerosis calcification of valves.

High incidence of diastolic dysfunction .

Cardiac adjustments to arterial stiffening during ageing

Cardiac response to increased flow

demand in the young and the elderly

Respiratory

Decreased lung tissue elasticity (due to reorganization of collagen

and elastin):

1• Early collapse of small airways and over distension of alveoli 01/Q

mismatch).

2• Increased residual volume (total lung capacity unchanged).

3• Increased closing capacity .

4• Decreased arterial oxygen tension.

5• Loss of alveolar surface area (increased anatomic and physiologic

dead space).

Increased V/Q mismatch.

Increased chest wall rigidity leading to increased work of breathing.

Blunted response to hypercapnia, hypoxia, and mechanical stress.

Decreased protective reflexes (coughing and swallowing) increasing

the risk for aspiration.

Increased pulmonary vascular resistance and pulmonary arterial

pressure.

Blunted hypoxic pulmonary vasoconstrictive response.

Renal

Decreased renal mass:

• Mostly renal cortex secondary to decreased functioning

glomeruli.

• Progressive decline in creatinine clearance.

• Increased risk of perioperative acute renal failure.

Decreased renal blood flow:

• Decreases 10% every decade of aging.

• Serum creatinine unchanged due to loss of muscle mass.

Decreased tubular function:

• Altered sodium balance, urine concentrating ability. and drug

excretion

• Increased risk for dehydration and electrolyte abnormalities.

Decreased renin-aldosterone system resulting in impaired

potassium excretion.

S. Cr. is a poor predictor of renal function in elderly patients.

Neurologic

Decreased brain mass, particularly the cerebral cortex (frontal lobes).

Cerebral blood flow decreases lD-20%, although auto regulation stays

intact.

Decreased neurotransmitter synthesis: GABA, serotonin, dopamine,

norepinephrine, and acetylcholine system .

Variable degrees of cognitive function decline, especially short-term

memory.

Decreased general anesthesia (MAQ and local anesthetic requirement.

Neuraxial changes

a) reduction of the area of the epidural space, increased

permeability of the Dura, and decreased volume of CSF.

b) The diameter and number of myelinated fibers in the dorsal and

ventral nerve roots are decreased. c) decreased conduction

velocity in peripheral nerves.

These changes tend to make elderly individuals more sensitive to

neuraxial and PNBs.

A)Reduction of the area of the epidural space, increased

permeability of the dura , and decreased volume of CSF.

B) The diameter and number of myelinated fibers in the dorsal and

ventral nerve roots are decreased.

C) decreased conduction velocity in peripheral nerves.

These changes tend to make elderly individuals more sensitive to

neuraxial and PNBs.

Gastrointestinal

Decreased liver function secondary to reduced liver mass and

hepatic blood flow:

• Reduced biotransformation .

• Decreased albumin production.

• Decreased plasma cholinesterase.

Delayed gastric emptying .

Increased gastric pH .

Musculoskeletal

Reduced muscle mass; atrophic skin; frail veins.

Increased body fat; total body water decreases.

Arthritis can affect various joints that can complicate

positioning.

Degenerative changes of the cervical spine; intubation

potentially more difficult.

Endocrine/metabolic

Atrophy of endocrine glands leading to impaired hormone

function:

Insulin, thyroxine, growth hormone, testosterone.

Blunted neuroendocrine stress response.

Decreased heat production and alteration in hypothalamic

temperature-regulating center.

increases risk of hypothermia.

Age-related pharmacologic effects

Increased body fat and decreased total body water:

Higher plasma concentration of water-soluble drugs.

Lower plasma concentration of fat-soluble drugs.

Reduced clearance secondary to decreased hepatic and

renal function.

Altered protein binding:

Reduced albumin affects binding of acidic drugs (opioids.

barbiturates, benzodiazepines).

Increased a,-acid glycoprotein after binding of basic drugs

local anesthetics).

Pharmacodynamics changes:

Drug effects may be intensified due to decreased number of

available receptors .

Reduced anesthetic requirement (or Mac).

Preoperative Evaluation

Perform a thorough history and physical examination (based on

clinical correlate) .

Assess optimization of preexisting conditions such as CAD,

hypertension, or diabetes .

Review medication history as polypharmacy is common among

the elderly, increasing the risk of medication interaction .

The decision to operate should not be based on age alone, but

should reflect an assessment of the risk-to-benefit ratio of individual

cases.

INTRAOPERATIVE

Monitoring based on procedure type and underlying organ involvement

Careful titration of anesthetic agents with cardiac- and respiratory-

depressant effects.

Careful attention toward fluid management to avoid fluid overload; at

the same time maintain adequate hydration/tissue perfusion.

Age-related respiratory effects as well as coexisting pulmonary disease

may necessitate vigorous preoxygenation.

Avoid hypothermia.

Regional anesthesia is a reasonable choice:

Local anesthetic dose requirement is typically reduced;

reduce local anesthetic dose for spinal anesthesia by 40% .

Increased risk of hypotension from the sympathectomy

.

Age-related Effects On Anesthetic Agents

Postoperative Management

Optimal pain management to improve respiratory effort, prevent

delirium, and promote early ambulation.

Higher incidence of perioperative complications in the elderly due

to age-related .

physiologic changes as well as associated comorbidities:

* Infection

* Thromboembolism

* Respiratory: most common morbidity for reasons mentioned

above

Cardiovascular: MI and cardiac arrest more common in elderly.

Stroke: risk factors are age, atrial fibrillation, and history of previous

stroke.

Postoperative confusion, delirium, or cognitive dysfunction common

in elderly.