Extended Emergence Strategy on Post-Anesthesia Care Unit Events After Outpatient Orthopedic Surgery (PACU-EMERGE)

Extended Emergence Trajectory on Post-Anesthesia Care Units Events in Ambulatory Lower-Extremity Orthopedic Surgery: A Randomized Controlled Trial

The goal of this clinical trial is to learn if an extended emergence from anesthesia can improve recovery room (Post-Anesthesia Care Unit or PACU) outcomes in lower-leg or foot surgery with nerve blocks. The primary questions it aims to answer are:

• Does a longer wake-up help participants think more clearly soon after surgery compared with usual approaches?
• Does it lower pain scores, lower the amount of pain medications used, and shorten the time it takes to go home from recovery room?

Researchers will compare 2 groups of adults who are having similar lower-extremity orthopaedic surgeries with regional and propofol anesthesia.

Study Overview

• Status: Not yet recruiting
• Conditions: Perioperative Care; Delirium - Postoperative; EEG Power Spectra
• Intervention / Treatment: Procedure: Standard of Care EEG-Guided Emergence; Procedure: Extended EEG Emergence Trajectory

• Study Type: Interventional
• Enrollment (Estimated): 300
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • California
    • Redwood City, California, United States, 94063
      • Stanford Medicine Outpatient Center
      • Principal Investigator: Harrison S Chow, MD, Msc.
      • Sub-Investigator: Makoto Kawai, MD, Dsc.

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Participants with American Society of Anesthesiologists (ASA) physical status I-III
• Scheduled for Elective Foot/Ankle Orthopaedic surgery at Stanford Health under planned propofol-based intravenous anesthesia and regional nerve block for preoperative analgesia
• Able and willing to complete all cognitive assessments and Brice Interview in PACU

Exclusion Criteria:

• ASA physical status IV or V
• Chronic opioid therapy
• Chronic benzodiazepine use or ongoing treatment with strongly anticholinergic medications within 30 days prior to surgery.
• Known major neuro-cognitive disorder, active psychotic disorder, or other severe psychiatric condition that, in the opinion of the investigator, would interfere with valid cognitive testing.
• Active cardiac or neurological stimulators or pumps in use
• Severe uncorrected visual or hearing impairment that precludes valid cognitive battery or interview completion.
• Inability to speak and understand the study language sufficiently to provide informed consent and complete study assessments.
• Inability to provide informed consent or lack of a legally authorized representative when required.
• Concurrent participation in another interventional study that could confound PACU cognitive or delirium outcomes.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Foot and ankle surgery with standard of care EEG emergence; Participants undergoing routine foot and ankle surgery will be given a routine standard of care intraoperatively at standard Patient Status Index (PSI) readings.	Procedure: Standard of Care EEG-Guided Emergence; Participants in this arm will undergo standard-of-care emergence from general anesthesia, with anesthetic management and timing of emergence determined by the treating anesthesiologist according to usual institutional practice. Continuous frontal EEG monitoring will be available as part of routine intraoperative monitoring; however, anesthetic discontinuation, adjustment of anesthetic dose, and timing of tracheal extubation will not follow a protocolized extended EEG target (for example, there is no requirement to maintain PSI greater than 50 for a predefined duration before extubation).
Experimental: Foot and ankle surgery with extended EEG emergence trajectory; Participants undergoing routine foot and ankle surgery will be given an experimental EEG emergence trajectory at end-operation held at PSI greater than 50 for a minimum of 5 minutes.	Procedure: Extended EEG Emergence Trajectory; Participants receive protocolized extended emergence guided by continuous frontal EEG monitoring during the final phase of anesthesia. Anesthesiologists will titrate anesthetic dosing to achieve and maintain a pre-specified emergence EEG pattern characterized by a persistent, organized posterior-dominant beta rhythm and return of higher-frequency activity, corresponding to a Patient State Index (PSI) greater than 50 for at least 5 consecutive minutes before tracheal extubation. Standard intraoperative hemodynamic and respiratory management will be maintained per routine care.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Time to Meet Post Anesthesia Care Unit (PACU) Discharge Criteria	Study will measure time in minutes from PACU arrival to the first documentation of institutional PACU discharge criteria being met.	Up to 2-5 hours post-surgery with discharge criteria are met.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Trail Making Test (TMT) time to completion	TMT Parts A and B is administered preoperatively and again in the early postoperative PACU period to assess attention, processing speed, and executive function. The outcome is the change in completion time (seconds) for TMT-A and TMT-B between postoperative and preoperative assessments (postoperative minus preoperative), with higher values indicating slower performance and worse cognitive function.	preoperative baseline (at arrival to pre-induction floor) to early postoperative PACU assessment (within 2 hours of PACU arrival)
Change in Digit Symbol Substitution Test (DSST) performance	DSST will be administered preoperatively and postoperatively in the PACU to assess psychomotor speed, attention, and working memory. The outcome is the change in number of correctly matched symbols between postoperative and preoperative assessments (postoperative minus preoperative), with negative values indicating a decline in performance.	preoperative baseline (at arrival to pre-induction floor) to early postoperative PACU assessment (within 2 hours of PACU arrival)
Pain intensity during PACU stay measured by Numeric Rating Scale (NRS)	Pain intensity will be assessed using an 11-point Numeric Rating Scale (NRS; 0 = no pain, 10 = worst imaginable pain) during the PACU stay.	From PACU arrival to discharge in 15 minute increments (within 24 hours)
Total opioid consumption in the PACU in morphine milligram equivalents	All opioid medication dosages will be converted to morphine milligram equivalents (MME) using standard equianalgesic conversion factors, and summed to obtain the total opioid consumption per participant during the PACU stay.	From PACU arrival to pre-induction until PACU discharge (up to 24 hours)
Incidence of dreaming assessed by modified Brice questionnaire	A modified Brice questionnaire will be administered after anesthesia to assess intraoperative dreaming, including any explicit recall of events and reports of dream experiences.	Within 5 minutes of arrival into PACU
Incidence of awareness assessed by modified Brice questionnaire	A modified Brice questionnaire will be administered after anesthesia to assess intraoperative awareness, including any explicit recall of events and reports of dream experiences.	Within 5 minutes of arrival into PACU

Collaborators and Investigators

• Sponsor: Harrison Shong-Wen Chow
• Investigators: Principal Investigator: Harrison S Chow, MD, Msc., Stanford University; Study Director: Yuva Krishnapillai, BS, Stanford University

Publications and helpful links

General Publications

• Hesse S, Kreuzer M, Hight D, Gaskell A, Devari P, Singh D, Taylor NB, Whalin MK, Lee S, Sleigh JW, Garcia PS. Association of electroencephalogram trajectories during emergence from anaesthesia with delirium in the postanaesthesia care unit: an early sign of postoperative complications. Br J Anaesth. 2019 May;122(5):622-634. doi: 10.1016/j.bja.2018.09.016. Epub 2018 Oct 25.
• Qin X, Chen X, Zhao X, Yao L, Niu H, Li K, Zhao Y, Liang Z, Lan Z, Wang Y, Guo X, Huang J, Li X. Electroencephalogram prediction of propofol effects on neuromodulation in disorders of consciousness. Front Neurol. 2025 Sep 29;16:1637647. doi: 10.3389/fneur.2025.1637647. eCollection 2025.
• Chen Y, Zou Y, Zhao X, Zhang L. Effects of EEG-guided anesthetic depth monitoring on delirium incidence across different age groups: a systematic review and meta-analysis. BMC Anesthesiol. 2026 Jan 28;26(1):153. doi: 10.1186/s12871-026-03631-3.
• Cascella M, Fusco R, Caliendo D, Granata V, Carbone D, Muzio MR, Laurelli G, Greggi S, Falcone F, Forte CA, Cuomo A. Anesthetic dreaming, anesthesia awareness and patient satisfaction after deep sedation with propofol target controlled infusion: A prospective cohort study of patients undergoing day case breast surgery. Oncotarget. 2017 Apr 19;8(45):79248-79256. doi: 10.18632/oncotarget.17238. eCollection 2017 Oct 3.
• Zierau M, Li D, Lapointe AP, Ip KI, McKinney AM, Thompson A, Puglia MP, Vlisides PE. Cortical Oscillations and Connectivity During Postoperative Recovery. J Neurosurg Anesthesiol. 2021 Jan;33(1):87-91. doi: 10.1097/ANA.0000000000000636.
• Chander D, Garcia PS, MacColl JN, Illing S, Sleigh JW. Electroencephalographic variation during end maintenance and emergence from surgical anesthesia. PLoS One. 2014 Sep 29;9(9):e106291. doi: 10.1371/journal.pone.0106291. eCollection 2014.
• Ren X, Huiqiao L, Wu Y, Zhang T, Chen P, Li L, Zhao G, Wang F. Perioperative neurocognitive disorders: a comprehensive review of terminology, clinical implications, and future research directions. Front Neurol. 2025 Aug 26;16:1526021. doi: 10.3389/fneur.2025.1526021. eCollection 2025.
• Sikka P, Ngo MC, Hu S, Wilkerson TB, Shull M, Imbordino K, Ishii T, Kawai M, Deverett B, Chow HS, Heifets BD. Feasibility of a Multicomponent Protocol to Promote Dreaming during Surgical Anesthesia. Anesthesiology. 2026 Apr 8. doi: 10.1097/ALN.0000000000005968. Online ahead of print.

Study record dates

Study Major Dates

• Study Start (Estimated): July 1, 2026
• Primary Completion (Estimated): September 1, 2027
• Study Completion (Estimated): October 1, 2027

Study Registration Dates

• First Submitted: April 8, 2026
• First Submitted That Met QC Criteria: April 9, 2026
• First Posted (Actual): April 16, 2026

Study Record Updates

• Last Update Posted (Actual): May 22, 2026
• Last Update Submitted That Met QC Criteria: May 19, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Postoperative delirium; Post-anesthesia care unit (PACU); EEG-guided anesthesia; Neurocognitive outcomes
• Additional Relevant MeSH Terms: Neurologic Manifestations; Nervous System Diseases; Mental Disorders; Postoperative Complications; Pathologic Processes; Confusion; Neurobehavioral Manifestations; Neurocognitive Disorders; Delirium; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Emergence Delirium
• Other Study ID Numbers: 85351

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: De-identified individual participant data underlying the primary and secondary outcome analyses will be shared, including a data dictionary and coding manual. No direct identifiers will be included
• IPD Sharing Time Frame: De-identified individual participant data (IPD) and supporting documentation will be made available beginning 6-12 months after publication of the primary results manuscript and will remain available for at least 5 years thereafter.
• IPD Sharing Access Criteria: Access will be granted to qualified investigators affiliated with academic or non-profit institutions for non-commercial, IRB-approved research projects that are consistent with the consent provided by participants. Requestors will be required to submit a brief research proposal and sign a data use agreement. After approval, data will be shared via secure, password-protected transfer or an institutional data repository.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No