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ANESTHESIA ALERT
Now let's look at this from an anesthetic standpoint. The MAC of
inhalational agents and the dosage of intravenous anesthetics
decrease with age. Maintaining normothermia may require additional
efforts because of impaired thermoregulation. Older patients may not
be able to tolerate decreases in blood pressure, and ischemia may
ensue because of atherosclerotic cerebral and carotid vessels. You
may need additional time and patience for the pre-operative evaluation, especially if your patients present with hearing difficulties and
dementias.
Cardiovascular risks
Because elderly patients have decreased vessel elasticity, they often
demonstrate increased systolic blood pressures and decreased diastolic blood pressures. The result? Increased pulse pressures.
Moreover, resting and maximum heart rate both decrease because of
a reduction in beta-adrenergic responsiveness and cardiac contractility. A general rule of thumb is that the maximum heart rate is equal to
220 minus age in years. So, an 80-year-old would have a maximal heart
rate of 140.
Baroreflexes also become impaired, due to reduced arterial compliance, making it hard for elderly patients to maintain their cardiac output during hypotensive episodes by increasing their heart rate (cardiac
output = stroke volume x heart rate). About 65% of 70-year-olds have
hypertension, and 30% of 75-year-olds have coronary artery disease. At
age 80, 70% experience congestive heart failure, and valvular disease
has a prevalence of 40% for mild disease and 13% for severe disease in
those aged 75 to 85.
From an anesthetic standpoint, elderly patients may experience
more profound hypotensive effects from inhalational and intravenous
agents. They may also require invasive monitoring, like an arterial line,
J U N E 2013 | O U T PAT I E N T S U R G E R Y M A G A Z I N E O N L I N E
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