Intraoperative Considerations

Monitored anesthesia care: Patients who are given a local anesthetic or no anesthetic should be monitored closely by an anesthesiologist. Monitored anesthesia care consists of monitoring the patient's vital signs and providing sedation as needed. It is often used with procedures such as cataract surgery, pacemaker placement, inguinal hernia repair, and extracorporeal shock wave lithotripsy.

Regional anesthesia: Spinal or epidural anesthetic techniques or blockade of major nerves (eg, of the cervical plexus for carotid endarterectomy or the brachial plexus for arm surgery) may be used to produce regional anesthesia. Spinal or epidural anesthetic techniques can be used for surgery of the lower abdomen, pelvis, or legs; they produce profound sympathetic block, which may cause hypotension, especially in patients who are hypovolemic. Local anesthetics administered epidurally have a faster onset and greater dermatomal spread in elderly persons than in younger persons.

General anesthesia: General anesthesia involves loss of consciousness, amnesia, pain relief, and a variable degree of muscle relaxation depending on the choice of volatile agent or use of a neuromuscular blocker. Most general anesthetics are potent myocardial depressants and vasodilators. Usually, an endotracheal tube is inserted into the patient's airway to control ventilation.

Doses of the induction agents etomidate, midazolam, propofol, and thiopental should be significantly lower for elderly patients than for younger patients. Ketamine and etomidate have minimal effects on the cardiovascular system and thus may be the induction agents of choice for the elderly.

The volatile anesthetics halothane, enflurane, isoflurane, sevoflurane, and desflurane impair the already attenuated chemoreceptor response in the elderly. The minimal alveolar concentration of these drugs decreases linearly with age, so that a smaller dosage is required to achieve anesthetic levels.

Neuromuscular blockers eliminated in urine or bile have a prolonged duration of action in the elderly, whereas the neuromuscular blockers atracurium, cisatracurium, and mivacurium do not. Little information is available about how aging affects succinylcholine activity, but the drug's circulatory time is thought to be longer in the elderly, allowing more time for hydrolysis of the drug. Thus, the initial dose of succinylcholine may need to be larger for elderly patients than for younger patients.

Opioids have a prolonged duration of action and decreased clearance in the elderly, who are more sensitive to them than younger persons are. The sedative and respiratory depressant effects of opioids may contribute to the postoperative pulmonary complications that frequently occur in the elderly. Remifentanil, a new, potent ultrashort-acting opioid, may be useful intraoperatively for elderly patients, because it is metabolized by nonspecific plasma esterases and, unlike other opioids, its elimination is unaffected by aging.

For elderly patients undergoing hip fracture surgery, regional or general anesthesia is appropriate. The consensus is that regional and general anesthetic techniques do not differ in effect on short-term or long-term survival in these patients and do not alter the incidence of postoperative confusion. Regional techniques provide some protection against deep venous thrombophlebitis but do not improve long-term outcome.

Other age-related operative issues (see Table 27-1): Obtaining vascular access to place monitoring devices and to administer drugs, fluids, and blood can be difficult in the elderly. Their veins are fragile, and arthritic changes may make positioning for central line placement difficult. Arthritic changes in the neck and jaw can also make intubation difficult; fiberoptic techniques may offer an advantage.

Because of age-related changes in temperature regulation, the elderly are prone to hypothermia during surgery. During anesthesia, the thermoregulatory center in the hypothalamus is anesthetized; patients are pharmacologically paralyzed and given sympathetic blocking agents. These measures further prevent heat production and promote heat loss.