Delirium occurs after major surgery in 5–50% of patients over the age of 50 years and is particularly common after hip fracture repair and aortic surgery, occurring in 30–60% of such patients. Postoperative delirium has been associated with higher rates of major postoperative cardiac and pulmonary complications, poor functional recovery, an increased length of hospital stay, an increased risk of subsequent dementia and functional decline, and increased mortality. Several preoperative and postoperative factors have been associated with the development of postoperative delirium, most notably age, preoperative functional or cognitive impairment, preoperative psychotropic drug use, and derangements of serum chemistry. Patients with multiple risk factors are at especially high risk. Delirium occurred in half of the patients with at least three of the risk factors listed in Table 3–6.
Two types of delirium reducing interventions have been evaluated: focused geriatric care and psychotropic medications. In a randomized, controlled trial of hip fracture surgery patients, those who received daily visits and targeted recommendations from a geriatrician had a lower risk of postoperative delirium (32%) than the control patients (50%). The most frequent interventions to prevent delirium were maintenance of the hematocrit > 30%; minimizing the use of benzodiazepines and anticholinergic medications; maintenance of regular bowel function; and early discontinuation of urinary catheters. Other studies comparing postoperative care in specialized geriatrics units with standard wards have shown similar reductions in the incidence of delirium. Although the use of neuroleptics to prevent postoperative delirium is uncommon, limited data support their effectiveness. A randomized trial in cardiac surgery patients demonstrated that risperidone (1 mg sublingual after regaining consciousness) reduced the incidence of postoperative delirium compared with placebo (11.1% vs. 31.7%). Another trial found that prophylactic oral haloperidol in orthopedic surgery patients failed to prevent delirium but did reduce its severity and duration.
Postoperative cognitive dysfunction is defined as a reduction in memory, language comprehension, visuospatial comprehension, attention, or concentration. Postoperative cognitive dysfunction may occur in up to 25% patients after cardiopulmonary bypass and in 15% of patients after major noncardiac surgery. The symptoms are generally transient, lasting < 3 months. It is more common in older patients and occurs with equal frequency after general or regional anesthesia.
Stroke complicates < 1% of all surgical procedures but may occur in 1–6% of patients undergoing cardiac or carotid artery surgery. Most of the strokes in cardiac surgery patients are embolic in origin, and about half occur within the first postoperative day. Stroke after cardiac surgery is associated with significantly increased mortality, up o 22% in some studies. A prediction model for stroke after coronary artery bypass surgery includes the following risk factors: age > 60 years, female sex, urgent or emergency surgery, diabetes mellitus, chronic kidney disease, peripheral vascular disease, and systolic dysfunction.
Symptomatic carotid artery stenosis is associated with a high risk for stroke in patients undergoing cardiac surgery.In general, symptomatic carotid lesions should be treated prior to elective cardiac surgery. In contrast, most studiessuggest that asymptomatic carotid bruits and asymptomatic carotid stenosis are associated with little or no increased risk of stroke in surgical patients. Prophylactic carotid endarterectomy in patients with asymptomatic carotid artery disease is unlikely to be beneficial in most patients, as the stroke risk of the carotid procedure likely outweighs any risk reduction it provides in a subsequent operation. On the other hand, patients with carotid disease with independent indications for carotid endarterectomy (see Chapter 12) should probably have the carotid surgery prior to the elective surgery.
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