Postoperative delirium affects a wide range of the general surgical population, with rates reported to be between 9 and 87 percent, depending on patient age and type of operative procedure. This adverse event has been associated with poor outcomes, such as increases in length of hospital stay, likelihood of being discharged to a rehabilitation center or nursing facility rather than home, mortality and higher cost of care. Also, postoperative delirium may have long-term effects on neurocognitive function.
Anesthesiologists must identify patients at risk for the adverse event, use strategies to prevent it and diagnose and treat it effectively. Christopher G. Hughes, M.D., M.S., an Associate Professor of Anesthesiology from the Department of Anesthesiology at Vanderbilt University Medical Center, will address these issues during the session “Postoperative Delirium: The Known Knowns, Known UnKnowns, and UnKnown UnKnowns.”
Postoperative delirium is widely recognized as a risk for older patients, a rapidly growing population. However, old age is not the only “known known.”
“Older patients are definitely at high risk, but there are other populations with significant risk as well,” Dr. Hughes said. “Delirium commonly develops in patients with substantial frailty and comorbid disease, even with only minor surgical insults. Delirium also develops in a high percentage of patients who have emergency surgery, cardiac surgery or major intra-abdominal surgery.”
Precipitating clinical risk factors also exist, such as the use of benzodiazepines, oversedation and poor analgesia. Dr. Hughes encourages anesthesiologists to consider patients’ baseline cognitive status.
Given these risk factors, what is the optimum approach to preventing postoperative delirium? Unfortunately, the best strategies, including anesthetic techniques, are “known unknowns.” However, Dr. Hughes does offer some advice.
“We must be efficient with the drugs we give. In other words, use as few as possible at the lowest dose, with a specific reason for everything. Good pain control and early mobility are also really important,” he said.
Diagnosis is another challenge. Several assessment tools have been developed and validated, but no comparative trials have provided definitive data on the best tool for assessing delirium postoperatively. Dr. Hughes recommends one of the shorter tools, such as the Confusion Assessment Method for the ICU (CAM-ICU), the CAM-based scoring system for severity of delirium (CAM-S), or 4AT, because they fit better into the clinical workflow.
Dr. Hughes also will address aspects of postoperative delirium he thinks are likely to arise in the future but have not attracted much attention yet. These aspects include the importance of severity or clinical phenotype of delirium on outcomes and whether decreasing the prevalence of delirium can alter mortality rates or cognitive decline.
“For most people, preservation of their ability to think is more important than survival,” Dr. Hughes said. “The brain is at the center of what we do as anesthesiologists and anesthetists. Yet, delirium, a sign of acute brain organ dysfunction, is often treated as a predetermined consequence of our actions. That historical approach is no longer acceptable, as delirium is one of the strongest factors in determining long-term brain function and quality of life in our patients.”