GERIATRICS

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GERIATRICS

• Donna Nyght, CRNA

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GERIATRIC POPULATION

• Growing faster than any other age group
• In 2000, 50 million Americans gt70
• 13 of general population

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PATIENTS OVER AGE 65

• Over half will have at least 1 surgery
  anesthetic before dying
• Aging process concomitant diseases increase
  risk of morbidity mortality
• Emergency surgery increases risk even more

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ANATOMIC PHYSILOGIC CHANGES

• Structural changes in cells organs
• Cell division fails
• Organ function shows linear decline with age
• Body fat increases
• Blood volume decreases
• Loss of protective reflexes
• Inability to retain body heat
• Reduced lean body mass
• Loss of skin elasticity
• Loss of collagen
• Intracellular water decreases

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Human Organ Function Declines with Age

• Linear decline
• After age 30, lose 1 per year functional
  capacity
• 60 y/o has 30 less function of any given organ
  system than a 30 y/o
• Healthy 30 y/o has 4-10 times the necessary organ
  function

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Administration of Anesthesia

• Body composition change has huge impact on pt.
  care
• Loss of skeletal muscle
• Blood volume reduced 20-30
• Body fat increases, so increase in lipid storage
• Prolonged effect of anesthetic

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Hypothermia

• Highly susceptible to decreases in temperature
• BMR declines with age
• Lack of autonomic peripheral vasoconstriction
• Shivering in PACU
• Postop protein catabolism

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Positioning

• Decreased range of motion
• Prevent trauma
• Use of padding

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Skin

• More sensitive to damage
• Tape
• Monitoring devices
• Collagen loss
• Elasticity of tissue decreases

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Airway

• Protective airway reflexes diminish
• Difficult mask fit
• Limited range of motion

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Cardiovascular

• Cardiac output reduced
• Impaired myocardial function
• Prolonged circulation time
• Delayed onset of drug effects
• Decreased organ perfusion
• Anesthetics cause myocardial depression and
  hypotension
• Higher incidence of CHF

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Cardiovascular

• Myocardial fiber atrophy
• Arterial vasculature loses elasticity
• LVH
• Increased peripheral vascular resistance
• Systemic hypertension
• CAD

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Cardiovascular

• Myocardium becomes thicker and stiffer in aging
  heart
• Atrial contraction becomes more important
• Loss of atrial contraction causes drop in
  systolic pressure
• Decreased response to adrenergic drugs

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Pulmonary

• Generalized reduction of elasticity
• Decrease in lung compliance
• Ventilation-perfusion mismatch
• Increased physiologic shunt
• Oxygen exchange diminished at alveoli

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Pulmonary

• Loss of skeletal muscle elasticity around alveoli
  and lung ducts
• Alveoli more distended at rest and less
  distensible during inspiration
• Closing volume increases

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Pulmonary

• Deterioration of intervertebral discs
• Loss of height
• ? total lung capacity
• Chest expansion restricted
• ? stiffness of thoracic cage
• Progressive dorsal kyphosis

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Pulmonary

• Surface area of alveoli ?
• Thickening of alveolicapillary membrane
• ? capillary blood flow
• PaO2 ? with age
• PaO2 - 100 - (0.4 age yrs mm Hg)

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Nervous System

• ? CNS activity
• Neuronal density decreased
• ? cerebral metabolic oxygen consumption
• Blood flow ?
• Neurotransmitter receptor sites ?
• Conduction velocity slows in peripheral nerves
• Reduced number of fibers in spinal cord tracts

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Nervous System

• Cognitive loss questionable
• Target organ for anesthetic agents
• Reduced requirements
• Required MAC of inhalation agent ?
• ? locals, narcotics, barbiturates,
  benzodiazepines, etc.

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Renal System

• GFR ? 6-8 per decade
• Renal blood flow ? 1-2 after age 25
• Reduced cardiac output
• Size of renal vascular bed diminished

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Renal System

• Impaired drug elimination
• Decreased ability to concentrate urine
• More susceptible to fluid overload
• ? ability to conserve water

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Hepatobiliary System

• ? blood flow
• Reduced plasma drug clearance

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Endocrine System

• Pancreatic function ?
• Higher incidence of diabetes
• Impaired ability to metabolize glucose

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Pharmacokinetics

• What the body does to the drug
• Drug absorption
• Tissue distribution
• Metabolism
• Elimination

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Pharmacokinetics

• Contracted vascular volume?high initial plasma
  concentration
• ? protein binding?availability of free drug
  increased
• ? total body adipose tissue?prolonged action of
  lipid-soluble drugs
• ? renal and hepatic blood flow?prolonged action
  of drugs dependent on kidney and liver
  elimination

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Pharmacodynamics

• What the drug does to the body
• Concentration of drug at site of action
• Intensity of effect
• Well documented that dose/MAC of anesthetic
  agents ?

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Pharmacodynamics

• ? barbiturate (pentothal) dose 30-40
• Decrease propofol dose
• More pronounced hypotension
• MAC of inhalation agents ?
• 4 ? per decade after age 40
• New agents good for geriatrics
• Less metabolism
• Low blood solubility
• Less depression of myocardium

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Pharmacodynamics

• Hepatic clearance reduced
• ? half-life and duration of narcotics
• ? half-life and duration of nondepolarizing
  muscle relaxants
• Prolonged effect of succinylcholine

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Anesthetic Management

• Consider anatomic and physiologic changes
• Need for adjustment of drug dosages
• Multiple disease processes

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History

• Extremely important!
• Need for information from family and other
  caregivers

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Patient Assessment

• Thorough history and physical exam
• Common coexisting diseases
• Hypertension
• Diabetes mellitus
• Coronary artery disease
• Chronic obstructive pulmonary disease
• Rheumatoid arthritis
• Osteoarthritis

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Patient Assessment

• Complete list of medications
• Look for drugs that prolong bleeding times
• Antihypertensive agents
• Careful assessment of allergies vs. side effects
  of drugs

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Patient Assessment

• Lab results
• Xrays
• ECG
• Other tests

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Premedication

• Lower versed dose
• Lower narcotic dose
• TITRATE!!!!

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Anesthetic Technique

• Choice of anesthetic technique based on
• Organ system function
• Effect of medications
• Surgical requirements
• Needs and susceptibilities of patient
• Hypotension
• Delayed drug clearance

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Monitoring

• Standard noninvasive monitors
• Debate about more aggressive use of invasive
  monitors in elderly

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Postanesthesia Recovery

• Cardiac and pulmonary complications are most
  common
• ? incidence of regurgitation and aspiration
• Longer duration of drugs
• More likely to develop CHF
• Unable to tolerate heat loss
• More likely to be confused and combative
• Increased risk of morbidity and mortality

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