The PACU functions as a triage center where decisions are made as to whether the patient is ready for discharge, transfer to the floor, or whether continued ICU-level of care is needed. Although the 2013 ASA Practice Guidelines for Postanesthetic Care include mental status assessment as routine perioperative care to detect complications and reduce adverse outcomes in postoperative patients, it often receives less attention compared to other monitored measures such as pain and respiratory or cardiac function (Anesthesiology 2013;118:291-307).

“The absence of scoring or assessment of delirium in the PACU is a missed opportunity to identify patients who are more likely to have delirium on subsequent hospital days and mitigate associated short- and long-term complications with postoperative delirium.”

Delirium is a common postoperative complication in older adults. Patients who develop delirium in the PACU are more likely to experience postoperative delirium on the floors and have increased risk of morbidity and mortality. A single incidence of delirium is associated with long-term cognitive decline and 10% increased risk of death (JAMA Intern Med 2023;183:442-50). Delirium specifically identified in the PACU has only recently gained recognition as part of the continuum of postoperative delirium (Figure). The incidence of PACU delirium is estimated to occur in 1.3% to 45% of surgical patients and varies according to study methodology and cohort of patients studied (Br J Anaesth 2017;119:288-90). Risk factors for PACU delirium include advanced age, longer preoperative fasting times, male gender, type of surgery, and use of certain perioperative drugs such opioids, benzodiazepines, or anticholinergics (Br J Anaesth 2017;119:288-90).


The presentation of delirium in patients can vary widely and is commonly defined as an acute fluctuation in awareness, attention, and cognition. Delirium may present as hyperactive, hypoactive, or a mix of both states. Hypoactive delirium may be more common in the elderly and is associated with higher mortality at six months after surgery (Psychosomatics 2009;50:248-54). However, without standardized assessment, hypoactive delirium often goes undetected (Arch Intern Med 2001;161:2467-73). Understanding the various presentations of delirium in the PACU is challenging as PACU delirium must also be correctly differentiated from pain and oversedation, which may present similarly.

The current assessment of mental status in early recovery stages in PACU often relies on the Aldrete Score, with 9-10 points meeting eligibility for PACU discharge (Anesth Analg 1970;49:924-34). However, the Aldrete incorporates only a quick assessment of consciousness, awarding a maximum of two points for consciousness (a patient who is arousable), which enables a low threshold to meet criteria for PACU discharge. There are several simple-to-use, validated tools specific to delirium that may help improve our assessment of mental status in the PACU (Table). The 4AT and 3D-CAM have been found to be the most accurate to detect delirium in the PACU according to a recent systematic review and meta-analysis, with sensitivities and specificities of 96% and 99%, and 100% and 88%, respectively (Age Ageing 2022;51:afac051; Ann Intern Med 2014;161:554-61; Aging Clin Exp Res 2022;34:1225-35).

The PACU environment may trigger a delirium episode in vulnerable patients for several reasons, including frequent noise, patient’s bedbound status, inaccessibility of hearing and visual aids, lack of family or familiar faces, lack of clocks, and an often windowless environment. Current practice does little to utilize delirium prevention strategies and represents another area of potential improvement. To enhance care for our patients, we should integrate prevention strategies into clinical practice. These include, but are not limited to: encouraging delirium assessment with validated scales by nursing in PACU, similar to inpatient units; minimizing patient tethers by “de-alarming” patients when possible; avoiding administration of Beers medications in the PACU; and providing PACU providers with postoperative delirium education.

The absence of scoring or assessment of delirium in the PACU is a missed opportunity to identify patients who are more likely to have delirium on subsequent hospital days and mitigate associated short- and long-term complications with postoperative delirium. This is particularly important in at-risk individuals such as older adults and those with baseline cognitive impairment, in whom the presence of delirium is independently associated with further impairment in cognitive function and decrease in performance of activities of daily living at one month and one year postoperatively (J Am Geriatr Soc 2010;58:643-9). Assessing delirium in the PACU offers an opportunity to identify patients who will have problems with delirium during their hospital stay and to implement timely strategies for prevention to improve patient outcomes.