- In the absence of coexisting disease, resting
systolic cardiac function appears to be preserved even in octogenarians.
Increased vagal tone and decreased sensitivity of adrenergic receptors
lead to a decline in heart rate.
- Elderly patients undergoing evaluation for surgery
have a high incidence of diastolic dysfunction that can be detected
with Doppler echocardiography.
- Diminished cardiac reserve in many elderly patients
may be manifested as exaggerated drops in blood pressure during
induction of general anesthesia. A prolonged circulation time delays
the onset of intravenous drugs but speeds induction with inhalational
- Elasticity is decreased in lung tissue, allowing
overdistention of alveoli and collapse of small airways. Airway
collapse increases residual volume and closing capacity. Even in
normal persons, closing capacity exceeds functional residual capacity
at age 45 in the supine position and age 65 in the sitting position.
When this happens, some airways close during part of normal tidal
breathing, resulting in a mismatch of ventilation and perfusion.
- Aging is associated with a decreasing response
to β-adrenergic agents (“endogenous β-blockade”).
- Impairment of sodium handling, concentrating
ability, and diluting capacity predisposes elderly patients to dehydration
or fluid overload. As renal function declines, so does the kidney’s
ability to excrete drugs.
- Hepatic function (reserves) declines in proportion
to the decrease in liver mass.
- Dosage requirements for local (minimum anesthetic
concentration) and general (minimum alveolar concentration) anesthetics
are reduced. Administration of a given volume of epidural anesthetic
tends to result in more extensive cephalad spread in elderly patients,
but with a shorter duration of analgesia and motor block. A longer
duration of action should be expected from a spinal anesthetic.
- Many elderly patients experience varying degrees
of an acute confusional state, delirium, or cognitive dysfunction
- Aging produces both pharmacokinetic and pharmacodynamic
changes. Disease-related changes and wide interindividual variations
even in similar populations lead to inconsistent generalizations.
- Elderly patients display a lower dose requirement
for propofol, etomidate, barbiturates, opioids, and benzodiazepines.
By the year 2040, people aged 65 or older are expected to make
up 24% of the population and account for 50% of
health care expenditures. Of these individuals half will require
surgery before they die, despite being at a 3-fold increased risk
for perioperative death compared with younger patients. Emergency
surgery, surgical site, and physical status defined by the American
Society of Anesthesiologists increase anesthetic risk (see Chapter 1). Operations associated with increased risk of perioperative mortality
and morbidity for elderly patients include thoracic, intraperitoneal
(particularly colon surgery), and major vascular procedures.
As with pediatric patients, optimal anesthetic management of
geriatric patients depends on an understanding of the normal changes
in physiology, anatomy, and response to pharmacological agents that
accompany aging. In fact, there are many similarities between elderly
and pediatric patients (Table 45–1).
Compared with pediatric patients, however, older people show a wider
range of variation in these parameters. The relatively high frequency
of serious physiological abnormalities in elderly patients demands
a particularly careful preoperative evaluation.
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