Chapter 84. Cognitive Dysfunction after Anesthesia and Surgery

1. Cognition represents key processes of memory, attention, perception, problem solving, and mental imagery that define who we are as individuals.

2. Cognitive functioning is key to the activities of daily living and our overall quality of life.

3. Cognitive assessment occurs by a number of well-validated measurements outlined in the field of neuropsychology. Assessment of cognitive functioning in the perioperative period is often less complete than normal; however, understanding what is measured by each individual test and how these values change over time is essential in understanding the implications to our patients of perioperative cognitive decline.

4. The incidence of postoperative cognitive dysfunction varies based on the sensitivity of the tests used and the time frame for evaluation. Correlation with appropriate control groups gives the best idea of the relative impact of surgery and anesthesia on changes in cognition and quality of life.

5. The etiology of cognitive function and/or cognitive dysfunction is complex and is associated with the severity of diseases including atherosclerosis and diabetes, as well as with surgery and anesthesia. The effect of anesthetic agents on short- and long-term cognition is controversial.

6. New studies indicate an association between patient factors including disease severity and genetic predisposition, and perioperative cognitive decline.

7. Determining the risks of perioperative cognitive decline enhances the probability of developing interventions to reduce cognitive decline and thus improve quality of life after surgery.

The brain is often a window to changes in blood flow, tissue perfusion, and early neural damage manifested by decline in higher cortical functions, including recall memory and cognitive processing. The elderly population in particular is at risk for cognitive deterioration as a consequence of reduced cognitive reserve seen with aging. These changes in cognitive function are associated with impaired activities of daily living, which substantially reduce the quality of life of the elderly. This can be magnified by physical or emotional stress in high-risk individuals.

The safety of anesthesia and surgery has progressed over several decades to the point that elderly and debilitated patients may safely undergo increasingly complex procedures with low risk of major morbidity or mortality. However, anesthesia and surgery appear to be associated with changes in cognitive functioning that outlast the effects of anesthesia or pain medications, inflammation, and the healing response. Several excellent studies have investigated changes in cognitive functioning associated with cardiac and noncardiac surgery.1-3

Understanding this decline and its etiology is complicated by the realization that anesthesia and surgery are rarely separated. This indicates that the differences may be caused by either the stress response associated with surgery or the administration of anesthetics. This chapter discusses the complex field of cognitive neurosciences and the intricate process of measuring and defining change in the perioperative period. Different types of surgery and implications for quality of life, as well as etiologic factors and how they relate to treatment are outlined.

Emergence delirium or emergence agitation, postoperative delirium (POD), postoperative cognitive dysfunction (POCD), and postoperative maladaptive ...