(Table 33-4: Effect of Age on Selected Perioperative Complications and Associated Mortality)
- Older patients are at increased risk for complications (cardiovascular, pulmonary, renal, central nervous system [CNS], wound infection, death) in the perioperative period, reflecting comorbid diseases and a reduction in organ system reserve because of the aging process.
- Complications of the cardiovascular and pulmonary systems are associated with the greatest perioperative mortality. The higher incidences of the pulmonary complications suggest that greater mortality results from pulmonary complications than cardiac complications.
- CNS complications are also a major source of morbidity and mortality. The incidence of stroke in the general surgical population is approximately 0.5%.
- Age is a risk factor, as is atrial fibrillation, and a history of a prior stroke increases the risk of perioperative stroke by as much as 10-fold.
- Strokes typically occur well after surgery (on average, 7 days later).
- Postoperative cognitive decline and postoperative delirium are significant sources of debilitating morbidity. Although these two entities may prove to be related to each other, at present they appear to be distinct clinical syndromes.
- Postoperative delirium is an acute confusional state manifested by a sudden onset (hours to days) and vacillating levels of attention and cognitive skill. Emergence delirium does not qualify as postoperative delirium.
- The risk of postoperative delirium after major surgery in older patients is approximately 10%. The risk varies with the surgical procedure and is highest after hip surgery, with an approximate incidence of 35%.
- The cause of delirium is multifactorial (Table 33-5: Risk Factors for Delirium in Elderly Patients).
- The choice of regional versus general anesthesia does not appear to be a factor, especially if sedation is used in conjunction with the regional technique.
- Delirium is associated with an increased duration of hospitalization and its attendant costs, poorer long-term functional recovery, and an increased mortality rate.
- Postoperative cognitive dysfunction is characterized by a long-term decrease in mental abilities after surgery. It is inherently more difficult to diagnose than delirium because it usually requires sophisticated neuropsychologic testing, including baseline tests before surgery.
- Compared with nonsurgical control subjects, the cognitive decline lessens over time, with a 25% incidence at 1 week and about a 10% incidence at 3 months.
- At 6 months and beyond, there may be a prevalence of 1% of subjects with cognitive decline.
- Anesthetic management does not appear to affect cognitive decline when comparisons are made between general versus regional anesthesia, controlled hypotension versus normotension, or IV versus inhalation anesthesia.
- Patient risk factors include older age, lower levels of education, and a history of stroke even without residual deficit.
- Increased mortality at 1 year is associated with patients who demonstrate cognitive decline at both hospital discharge and at 3 months after surgery.