Postoperative delirium in ambulatory patients

Ambulatory surgery is expanding rapidly in an aging, comorbid population, yet delirium prevention strategies remain designed for the inpatient setting. This review provides a mechanistic and pragmatic framework for postoperative delirium (POD) in ambulatory patients and proposes an operational algorithm for its diagnosis, differential diagnosis, prevention, and management.

POD is found in approximately 17.7% of cases following noncardiac procedures overall, but appears markedly less frequent in the ambulatory setting (<2%), potentially reflecting less invasive procedures, the widespread use of regional anesthesia, and limited exposure to hospital-related precipitating factors. This apparent low frequency creates a detection gap: once the patient is home, screening depends on caregivers. The Family Confusion Assessment Method shows good agreement with clinician-rated Confusion Assessment Method and, when embedded in structured telephone or telehealth follow-up, extends surveillance to postoperative day 30. Preventive levers now supported by data include multimodal prehabilitation (11.7-8.2%), individualized blood pressure targets, electroencephalography-guided depth of anesthesia, and family-delivered multicomponent programs (t-HELP; 19.4-2.6%). Neuronal-injury biomarkers, particularly phosphorylated Tau181 (pTau181), argue for a pathway shared with neurodegeneration.

POD predominantly affects patients over 65 years of age and carries increased morbidity, mortality, and long-term cognitive decline; more than 30% of cases are preventable. In ambulatory care, the challenge is not case volume but case detection: preoperative risk stratification supported by standardized protocols for multidisciplinary collection of clinical history from relatives, systematic exclusion of reversible organic causes, and caregiver-based screening after discharge. Rather than a low-risk setting by default, the ambulatory pathway should be regarded as an active preventive strategy for frail older patients.