Chapter 45

• 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 agents.
• 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 postoperatively.
• 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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