Intraoperative AwarenessEXPLICIT-RCLNCT05857618
Study to Determine if Patients Exposed to General Anesthesia Significant Numbers of Times Would Increase the Risk for Intraoperative Awareness.
An observational study of Intraoperative Awareness and General Anesthesia, run by University of Chicago at 1 site in United States.
Trial summary
This study will detect whether prior exposure to general anesthesia multiple times is associated with an increased incidence of awareness with explicit recall (AWR). This is especially important because patients who need to undergo multiple events of general anesthesia are medically some of the most vulnerable… Read more about this study
- Who is it for?
- Ages 7 years and older
- Conditions the study is for
- Intraoperative Awareness, General Anesthesia
- How many people
- 1,000 participants
- Where
- 1 siteUnited States
- Study dates
- 19 Jul 2017to 1 Jun 2027
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 7 years and older
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Study population: Patients from the University of Chicago Medical Center who are 7 years or older who have been exposed to general anesthesia either less than 5 times or greater than 20 times.
Who may be able to join
- Patients who have been exposed to general anesthesia greater than 20 times or who have been exposed to general anesthesia 5 or fewer times between January 1, 1985 and June 15, 2017
- Patients/their Guardians who consent to participate in the study.
- Patients for whom a determination of AWR status can be made by anesthesiologists based on a standardized criteria.
- Must be at least 7 years of age or older.
Who cannot join
- Healthy volunteers,
- Patients who cannot recall whether or not they have experienced intraoperative awareness with explicit recall
Trial locations and contacts
1 site in 1 country.
United States1 site
University of Chicago Medical Center
Chicago, Illinois, 60637
About this study
Official title: A Survey and Chart Review to Determine if Patients Exposed to General Anesthesia Significant Numbers of Times Would Increase the Risk for Intraoperative Awareness With Explicit Recall.
This study will detect whether prior exposure to general anesthesia multiple times is associated with an increased incidence of awareness with explicit recall (AWR). This is especially important because patients who need to undergo multiple events of general anesthesia are medically some of the most vulnerable populations. The study hypothesizes that patients with significant exposure to general anesthesia have a higher incidence of AWR. This study may help clinicians and patients to better understand how to manage anesthesia care so that the safety and comfort of patients can be improved.
Read the detailed description
Each year, tens of millions of Americans undergo general anesthesia. One of the biggest fears patients have regarding general anesthesia is experiencing intraoperative awareness. That means that the patients "wake" during surgery and become aware of their environment. Prior studies have shown that intraoperative awareness with explicit recall (AWR) occurs in 0.1%-0.2% of patients undergoing general anesthesia. Patients have reported different forms of AWR, including feeling the sensation of pain, difficulty breathing, or recalling conversations. AWR can leave a lasting negative effect on patients. In one study, 56.3% of patients who experienced AWR met the diagnostic criteria for PTSD with functional impairment. Another study found that PTSD was experienced by as many as 70% of patients who had AWR.5 These patients fear undergoing further medical treatment requiring anesthesia and suffer quality of life issues related to their episode(s) of AWR. The goal of this study is to determine whether there is a particular group of patients, those that have been anesthetized many times, at high risk for AWR and then to design protocols to prevent this from happening.
Rationale for Conducting this Research
While the incidence of intraoperative awareness with explicit recall (AWR) is 0.1%-0.2% in general population undergoing general anesthesia, higher incidence has been reported in the populations with special risk factors, such as obstetric, cardiac and trauma surgeries. Patients with a history of awareness are at increased risk of intraoperative awareness. However, it is not certain whether this association is related to the number of anesthesia exposure or the development of resistance to anesthetics in these patients. Prior studies have demonstrated that the incidence of AWR in females is threefold higher than in males and that AWR is higher in patients with difficult airways and in patients with drug addiction. In addition, patients with an ASA Status of III-V had a greater than 2.4 odd of AWR than patients with an ASA Status of I-II. Most recently, we took care of two young adult patients who had more than 20 surgeries requiring general anesthesia since their childhood and reported multiple incidents of AWR. One of patients had a new episode of AWR during a regular surgery a few months ago despite extra measures were taken by her anesthesiologists. In addition, we found animals that were anesthetized multiple times showed change in their sensitivity to general anesthetics. To date, there has not been a study that has looked at whether patients who have undergone general anesthesia a significant number of times (n>20) have a higher incidence of AWR.
Primary Objective
To determine whether patients who have undergone general anesthesia significant number of times have a significantly higher incidence of intraoperative awareness with explicit recall (AWR) as compared to the general population.
Secondary Objective Allows us to better understand the cause of AWR in this population. It may help us to improve clinical care and comfort for patients who are at a higher risk for intraoperative awareness.
Patients that meet the eligibility criteria will be contacted by phone to provide consent to participate in the study. Patients who refuse to consent will not be included in the study and that data will not be saved. Of the patients who consent, a standardized phone interview by trained interviewers will be carried out and this data will be collected and stored in an encrypted computer hard drive. This data will be reviewed by anesthesiologists using a standard criteria to elucidate whether the patient experienced intraoperative awareness with explicit recall. The questionnaire includes the common complaints from the report of a North American anesthesia awareness registry. In addition to the questionnaire, the study team will perform a chart review on eligible patients collecting data on thier medical and surgical history, current medications and clinical situations when AWR occurred.
- Conditions
- Intraoperative Awareness, General Anesthesia
- Keywords
- explicit recall, Intraoperative, Intraoperative awareness, General Anesthesia, Intraoperative recall
- Medical subject headings
- Intraoperative Awareness
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| Patients who have undergone exposer to General Anesthesia | Patients who have undergone general anesthesia at the University of Chicago Medical Center more than 20 times or patients who have general anesthesia 5 or fewer times in the past. |
What is being measured
The primary outcome is the main question the study is designed to answer.
Intraoperative Awareness with Explicit Recall for patients who underwent more than 20 general anesthesia events
The Number of incidences of intraoperative awareness with explicit recall with patients undergoing general anesthesia greater than 20 times using the 5-question modified Brice questionnaire
Measured: Until study completion; up to 1 year.
Secondary outcomes (1)
Intraoperative Awareness with Explicit Recall for patients who underwent less than 5 general surgeries involving general anesthesia
The Number of incidences of intraoperative awareness with explicit recall with patients undergoing general anesthesia less than 5 times using the 5-question modified Brice questionnaire
Measured: Until study completion; up to 1 year.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted12 May 2023
- Study start19 Jul 2017
- Primary completion1 Sep 2026 (estimated)
- Study completion1 Jun 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Intraoperative AwarenessStudies of the same condition, open and under way.
- More trials run by University of ChicagoThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 1,000 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Chicago
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05857618
- Sponsor's protocol ID
- IRB 17-0929
- Acronym
- EXPLICIT-RCL
- Status last verified
- Jul 2025
- First submitted
- 18 Nov 2022
- Last updated
- 9 Jan 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 9 Jan 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Survey and Chart Review to Determine if Patients Exposed to General Anesthesia Significant Numbers of Times Would Increase the Risk for Intraoperative Awareness With Explicit Recall.
- ClinicalTrials.gov ID
- NCT05857618
- Acronym / sponsor ID
- EXPLICIT-RCL / IRB 17-0929
- Conditions
- Intraoperative Awareness, General Anesthesia
- Keywords
- explicit recall, Intraoperative, Intraoperative awareness, General Anesthesia, Intraoperative recall
- Study type
- Observational
- Recruitment status
- Active, not recruiting
- Enrolment
- 1,000 participants (estimated)
- Lead sponsor
- University of ChicagoUniversity, hospital or other
- Study start
- 19 Jul 2017 (actual)
- Primary completion
- 1 Sep 2026 (estimated)
- Study completion
- 1 Jun 2027 (estimated)
- First posted
- 12 May 2023 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study will detect whether prior exposure to general anesthesia multiple times is associated with an increased incidence of awareness with explicit recall (AWR). This is especially important because patients who need to undergo multiple events of general anesthesia are medically some of the most vulnerable populations. The study hypothesizes that patients with significant exposure to general anesthesia have a higher incidence of AWR. This study may help clinicians and patients to better understand how to manage anesthesia care so that the safety and comfort of patients can be improved.
Detailed description
Each year, tens of millions of Americans undergo general anesthesia. One of the biggest fears patients have regarding general anesthesia is experiencing intraoperative awareness. That means that the patients "wake" during surgery and become aware of their environment. Prior studies have shown that intraoperative awareness with explicit recall (AWR) occurs in 0.1%-0.2% of patients undergoing general anesthesia. Patients have reported different forms of AWR, including feeling the sensation of pain, difficulty breathing, or recalling conversations. AWR can leave a lasting negative effect on patients. In one study, 56.3% of patients who experienced AWR met the diagnostic criteria for PTSD with functional impairment. Another study found that PTSD was experienced by as many as 70% of patients who had AWR.5 These patients fear undergoing further medical treatment requiring anesthesia and suffer quality of life issues related to their episode(s) of AWR. The goal of this study is to determine whether there is a particular group of patients, those that have been anesthetized many times, at high risk for AWR and then to design protocols to prevent this from happening.
Rationale for Conducting this Research
While the incidence of intraoperative awareness with explicit recall (AWR) is 0.1%-0.2% in general population undergoing general anesthesia, higher incidence has been reported in the populations with special risk factors, such as obstetric, cardiac and trauma surgeries. Patients with a history of awareness are at increased risk of intraoperative awareness. However, it is not certain whether this association is related to the number of anesthesia exposure or the development of resistance to anesthetics in these patients. Prior studies have demonstrated that the incidence of AWR in females is threefold higher than in males and that AWR is higher in patients with difficult airways and in patients with drug addiction. In addition, patients with an ASA Status of III-V had a greater than 2.4 odd of AWR than patients with an ASA Status of I-II. Most recently, we took care of two young adult patients who had more than 20 surgeries requiring general anesthesia since their childhood and reported multiple incidents of AWR. One of patients had a new episode of AWR during a regular surgery a few months ago despite extra measures were taken by her anesthesiologists. In addition, we found animals that were anesthetized multiple times showed change in their sensitivity to general anesthetics. To date, there has not been a study that has looked at whether patients who have undergone general anesthesia a significant number of times (n>20) have a higher incidence of AWR.
Primary Objective
To determine whether patients who have undergone general anesthesia significant number of times have a significantly higher incidence of intraoperative awareness with explicit recall (AWR) as compared to the general population.
Secondary Objective Allows us to better understand the cause of AWR in this population. It may help us to improve clinical care and comfort for patients who are at a higher risk for intraoperative awareness.
Patients that meet the eligibility criteria will be contacted by phone to provide consent to participate in the study. Patients who refuse to consent will not be included in the study and that data will not be saved. Of the patients who consent, a standardized phone interview by trained interviewers will be carried out and this data will be collected and stored in an encrypted computer hard drive. This data will be reviewed by anesthesiologists using a standard criteria to elucidate whether the patient experienced intraoperative awareness with explicit recall. The questionnaire includes the common complaints from the report of a North American anesthesia awareness registry. In addition to the questionnaire, the study team will perform a chart review on eligible patients collecting data on thier medical and surgical history, current medications and clinical situations when AWR occurred.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Patients who have undergone exposer to General Anesthesia | – | –Patients who have undergone general anesthesia at the University of Chicago Medical Center more than 20 times or patients who have general anesthesia 5 or fewer times in the past. |
Who may qualify
- Ages
- 7 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
- Study population
- Patients from the University of Chicago Medical Center who are 7 years or older who have been exposed to general anesthesia either less than 5 times or greater than 20 times.
Key inclusion criteria (4 listed)
- Patients who have been exposed to general anesthesia greater than 20 times or who have been exposed to general anesthesia 5 or fewer times between January 1, 1985 and June 15, 2017
- Patients/their Guardians who consent to participate in the study.
- Patients for whom a determination of AWR status can be made by anesthesiologists based on a standardized criteria.
- Must be at least 7 years of age or older.
Key exclusion criteria (2 listed)
- Healthy volunteers,
- Patients who cannot recall whether or not they have experienced intraoperative awareness with explicit recall
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
Intraoperative Awareness with Explicit Recall for patients who underwent more than 20 general anesthesia events
Time frame: Until study completion; up to 1 year.
The Number of incidences of intraoperative awareness with explicit recall with patients undergoing general anesthesia greater than 20 times using the 5-question modified Brice questionnaire
1 secondary outcome
Intraoperative Awareness with Explicit Recall for patients who underwent less than 5 general surgeries involving general anesthesia
Time frame: Until study completion; up to 1 year.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 9 Jan 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Intraoperative Awareness and General Anesthesia, run by University of Chicago at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 2 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: under way, not looking for participants, as of the sponsor's last update on 9 Jan 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Intraoperative Awareness with Explicit Recall for patients who underwent more than 20 general anesthesia events (time frame: Until study completion; up to 1 year.). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 9 Jan 2026.