VOLUME 33, ISSUE 2

Once risk factors have been assessed, proper screening will allow us to quantitatively measure their baseline mental status prior to surgery. The American Geriatric Society (AGS) and the American Society of Anesthesiologists’ Perioperative Brain Health Initiative suggest the quick and easy Mini-Cog screening tool to assess cognitive impairment in the elderly. Patients are asked to recall 3 items and to draw a clock. This evaluation can be done in conjunction with acquiring informed consent for anesthesia.^4,5 Other prediction scores such as the Acute Physiological and Chronic Health Evaluation II (APACHE) have been used in assessing medical patients. There is also the comprehensive geriatric assessment (CGA) which requires a geriatrics consult as it includes medical, psychological, social and functional review. The CGA has been shown by several studies to reduce risk of postoperative delirium by improving identification of delirium and initiation of multimodal treatments based on minimizing the risk factors in Table 1.3 Regardless of the test, it is important that high risk elderly patients or those undergoing high risk surgeries should have baseline screening, given the known adverse consequences.

As far as practice-based interventions, there has been evidence to support minimizing preoperative fasting times, utilizing a multimodal approach to pain with opioid sparing regimens, using neuraxial anesthesia, and avoiding excessive depth of anesthesia. It is also important to avoid inappropriate drugs as mentioned in the AGS Beers Criteria, such as benzodiazepines, anticholinergics, and meperidine, that are strongly associated with delirium.⁶ Two large observational studies reported that regional anesthesia was independently associated with a 20-40% lower incidence of delirium³. This needs to be further investigated, however we know regional techniques can diminish post op pain, decrease the degree of depth of anesthesia required, and reduce a patient’s stress response. A recent meta-analysis reported no significant benefit in using a total intravenous technique over a general anesthetic with volatile agents in the reduction of postoperative delirium.⁷ Several studies have shown that increased depth of anesthesia is a risk factor for postoperative delirium.⁵ Monitoring the anesthetic depth with a modified electroencephalogram depth of anesthesia monitor as well as being cognizant of the volatile anesthetic concentration can be beneficial in order to avoid deep levels of anesthesia.

While there is no Food and Drug Administration approved pharmacologic intervention for treatment of delirium, there have been promising results with the use of dexmedetomidine. Dexmedetomidine is a selective alpha 2-receptor agonist and can reduce the expression of inflammatory mediators and neuroapoptosis. A meta-analysis demonstrated that administration of dexmedetomidine perioperatively significantly reduced postoperative delirium (odds ratio of 0.35).⁸ In addition, dexmedetomidine can be helpful in regulating the sleep cycle and may lead to longer periods of deep sleep. Sleep disturbance and cognitive dysfunction have long been associated. Other mediators of sleep include melatonin and ramelteon (a synthetic melatonin receptor agonist). These agents have been effective in reducing the risk of postoperative delirium.⁹

Non-pharmacologic interventions that help with cognitive re-orientation include minimizing transitions of providers, reorientation of the patient to their surroundings, natural light, time tracking, maintaining sleep-wake cycle, family time, and use of assist devices such as glasses, hearing aids, dentures can decrease delirium by up to 40%.^{3, 4,5} In addition to decreasing delirium, reorientation methods can lead to greater patient satisfaction.

Postoperatively, the Confusion Assessment Methods (CAM-ICU, 3D- CAM) and Nursing Delirium Screening Scale (NuDESC) have shown to be 90% specific in detection of delirium.¹ We most commonly associate the CAM-ICU with critical care patients, however the 3D-CAM demonstrated strong test performance (specificity 0.88, sensitivity 1.0) and, on average, can be done in 5 minutes.¹⁰ All high-risk patients should be screened for delirium prior to discharge from the recovery room and at the end of every shift on the hospital unit for the first five days after surgery in order to better detect patients with delirium. Once a diagnosis of delirium has been made, there are sparse treatment options available. First line management of delirium should include multicomponent non-pharmacological interventions like cognitive reorientation and avoidance of antipsychotic and benzodiazepines, unless the patient is severely agitated and are at risk of harm to themselves or others.⁵

In conclusion, anesthesiologists can make a substantial difference in recognition and prevention of postoperative delirium. We need to take the lead and work in collaboration with geriatricians and perioperative teams to create and implement formal educational programs on assessment, prevention, and management of delirium. These measures can impact patient outcomes and improve immediate and long-term care of a growing population of elderly high-risk patients.