Anesthesia, GeneralNCT00584324
Depth of Anesthesia on Implicit Memory
A study testing BIS 40 and BIS 60 in people with Anesthesia, General and Memory, run by University of Oklahoma at 1 site in United States.
Trial summary
Purpose of this study is to see if different levels of anesthesia have an effect on hearing spoken words without awareness of having heard them or anxiety after surgery. Read more about this study
- Who is it for?
- Ages 55 to 90 years
- Conditions the study is for
- Anesthesia, General, Memory
- What is being tested?
- BIS 40 and BIS 60
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 70 participants
- Where
- 1 siteUnited States
- Study dates
- Mar 2006to Jan 2012
- Phase
- Interventional
- Are there results?
- None posted in the registry
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 55 to 90 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Persons signing informed consent
- Elective general surgery for orthopedics (external or internal fixation) or urologic (transurethral)
- Literate
- Native English speaking
Who cannot join
- Hearing impaired
- History of cognitive dysfunction
- Subjects requiring post-operative sedation for any indication
Trial locations and contacts
1 site in 1 country.
United States1 site
University of Oklahoma Health Sciences Center
Oklahoma City, Oklahoma, 73104
About this study
Official title: The Effect of Depth of Anesthesia on Implicit Memory
Purpose of this study is to see if different levels of anesthesia have an effect on hearing spoken words without awareness of having heard them or anxiety after surgery.
Read the detailed description
Amnesia (lack of recall) is one of the most important goals of general anesthesia. Inadvertent free recall during a major surgical procedure is not only inhumane, but also predisposes the patient to morbidity such as post-traumatic stress disorder. Therefore, it is standard practice among anesthesiologists to inquire about free (explicit) recall during a post-anesthetic visit.
Free recall requires a functional long term memory. Historically, lack of free recall during general anesthesia has been regarded as complete absence of long term memory activity. However, recent evidence suggests that the relationship between general anesthesia and memory is more complex than previously thought.
Objectives of the proposed are twofold: (1) to test the presence of implicit memory under two different planes of surgical general anesthesia in elderly males (55-90 years old) during a uniform surgical procedure (urologic procedures via transurethral approach) (2) to compare the pre and postoperative anxiety levels as a marker of clinical significance of operational implicit memory function.
The study is divided into three phases: pre-operative, operative, and post-operative.
Pre-operative phase will consist of a cognitive function test (mini-mental state exam). This will be administered at the urology or pre-operative anesthesia clinic visit, after obtaining the informed consent of the patient.
Operative phase will start with a baseline anxiety test (Spielberger state-trait anxiety test) just before being taken to the operating room. This will be followed by playing an audio file (a list of spoken words) via headphones under general anesthesia during the surgical procedure.
Post-operative phase will have of a spoken word-stem completion test (just before discharge from the hospital) and a repeat of the anxiety test mentioned above (2 to 3 weeks post-operatively).
- Conditions
- Anesthesia, General, Memory
- Being tested
- BIS 40, BIS 60
- Keywords
- elective surgery, general anesthesia, implicit memory
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
BIS 40Combination product
Also called Mini-mental state exam, Spielberger State-Trait anxiety test, Spoken word-stem completion test, Bispectral Index Monitor
Mini-mental state exam: For subjects > 60, this exam will be administered pre-operatively.
Spielberger State-Trait anxiety test: Spielberger test just before being taken to the operating room.
Spoken word-stem completion test: After discharge from recovery but within 24 hrs. post surgery, this test along with the anxiety test will be administered.
Bispectral Index Monitor: The physiologic monitor is used intraoperatively to assess surgical anesthesia.
Audio File: Playing an audio file (a list of spoken words) via headphones under general anesthesia during the surgical procedure.
BIS 60Combination product
Also called Mini-mental state exam, Spielberger State-Trait anxiety test, Spoken word-stem completion test, Bispectral Index Monitor
Mini-mental state exam: For subjects > 60, this exam will be administered pre-operatively.
Spielberger State-Trait anxiety test: Spielberger test just before being taken to the operating room.
Spoken word-stem completion test: After discharge from recovery but within 24 hrs. post surgery, this test along with the anxiety test will be administered.
Bispectral Index Monitor: The physiologic monitor is used intraoperatively to assess surgical anesthesia.
Audio File: Playing an audio file (a list of spoken words) via headphones under general anesthesia during the surgical procedure.
| Study group | Role | What they receive |
|---|---|---|
| Bispectral Index (BIS) 40 | Experimental | Target BIS 40 Receives: Combination Product: BIS 40; Combination Product: BIS 60 |
| Bispectral Index (BIS) 60 | Experimental | Target BIS 60 Receives: Combination Product: BIS 40; Combination Product: BIS 60 |
What is being measured
The primary outcome is the main question the study is designed to answer.
To test the presence of implicit memory under two different planes of surgical general anesthesia in patients undergoing urologic (transurethral) or orthopedic (internal and external fixation) procedures
Measured: 3 years
Secondary outcomes (1)
To compare the pre and postoperative anxiety levels as a marker of clinical significance of operational implicit memory function.
Measured: 3
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted2 Jan 2008 (estimated)
- Study startMar 2006
- Primary completionJan 2012
- Study completionJan 2012
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Anesthesia, GeneralStudies of the same condition, open and under way.
- More trials run by University of OklahomaThe 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
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Supportive care
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 70 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Oklahoma
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Mehmet S. Ozcan, MD, Principal investigator, University of Oklahoma
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT00584324
- Sponsor's protocol ID
- 12634NotACT
- Status last verified
- Apr 2026
- First submitted
- 20 Dec 2007
- Last updated
- 7 Apr 2026
- Results posted
- No
- Data monitoring committee
- Yes
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 7 Apr 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Effect of Depth of Anesthesia on Implicit Memory
- ClinicalTrials.gov ID
- NCT00584324
- Acronym / sponsor ID
- 12634NotACT
- Conditions
- Anesthesia, General, Memory
- Keywords
- elective surgery, general anesthesia, implicit memory
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 70 participants (actual)
- Lead sponsor
- University of OklahomaUniversity, hospital or other
- Study start
- Mar 2006
- Primary completion
- Jan 2012 (actual)
- Study completion
- Jan 2012 (actual)
- First posted
- 2 Jan 2008 (estimated)
- 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.
Purpose of this study is to see if different levels of anesthesia have an effect on hearing spoken words without awareness of having heard them or anxiety after surgery.
Detailed description
Amnesia (lack of recall) is one of the most important goals of general anesthesia. Inadvertent free recall during a major surgical procedure is not only inhumane, but also predisposes the patient to morbidity such as post-traumatic stress disorder. Therefore, it is standard practice among anesthesiologists to inquire about free (explicit) recall during a post-anesthetic visit.
Free recall requires a functional long term memory. Historically, lack of free recall during general anesthesia has been regarded as complete absence of long term memory activity. However, recent evidence suggests that the relationship between general anesthesia and memory is more complex than previously thought.
Objectives of the proposed are twofold: (1) to test the presence of implicit memory under two different planes of surgical general anesthesia in elderly males (55-90 years old) during a uniform surgical procedure (urologic procedures via transurethral approach) (2) to compare the pre and postoperative anxiety levels as a marker of clinical significance of operational implicit memory function.
The study is divided into three phases: pre-operative, operative, and post-operative.
Pre-operative phase will consist of a cognitive function test (mini-mental state exam). This will be administered at the urology or pre-operative anesthesia clinic visit, after obtaining the informed consent of the patient.
Operative phase will start with a baseline anxiety test (Spielberger state-trait anxiety test) just before being taken to the operating room. This will be followed by playing an audio file (a list of spoken words) via headphones under general anesthesia during the surgical procedure.
Post-operative phase will have of a spoken word-stem completion test (just before discharge from the hospital) and a repeat of the anxiety test mentioned above (2 to 3 weeks post-operatively).
Study design
- Primary purpose
- Supportive care
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (participant, investigator)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Bispectral Index (BIS) 40 | Experimental | Combination Product: BIS 40, Combination Product: BIS 60Target BIS 40 |
| Bispectral Index (BIS) 60 | Experimental | Combination Product: BIS 40, Combination Product: BIS 60Target BIS 60 |
Who may qualify
- Ages
- 55 to 90 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- Persons signing informed consent
- Elective general surgery for orthopedics (external or internal fixation) or urologic (transurethral)
- Literate
- Native English speaking
Key exclusion criteria (3 listed)
- Hearing impaired
- History of cognitive dysfunction
- Subjects requiring post-operative sedation for any indication
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| BIS 40Also: Mini-mental state exam, Spielberger State-Trait anxiety test, Spoken word-stem completion test, Bispectral Index MonitorMini-mental state exam: For subjects > 60, this exam will be administered pre-operatively. Spielberger State-Trait anxiety test: Spielberger test just before being taken to the operating room. Spoken word-stem completion test: After discharge from recovery but within 24 hrs. post surgery, this test along with the anxiety test will be administered. Bispectral Index Monitor: The physiologic monitor is used intraoperatively to assess surgical anesthesia. Audio File: Playing an audio file (a list of spoken words) via headphones under general anesthesia during the surgical procedure. | Combination product | Bispectral Index (BIS) 40, Bispectral Index (BIS) 60 |
| BIS 60Also: Mini-mental state exam, Spielberger State-Trait anxiety test, Spoken word-stem completion test, Bispectral Index MonitorMini-mental state exam: For subjects > 60, this exam will be administered pre-operatively. Spielberger State-Trait anxiety test: Spielberger test just before being taken to the operating room. Spoken word-stem completion test: After discharge from recovery but within 24 hrs. post surgery, this test along with the anxiety test will be administered. Bispectral Index Monitor: The physiologic monitor is used intraoperatively to assess surgical anesthesia. Audio File: Playing an audio file (a list of spoken words) via headphones under general anesthesia during the surgical procedure. | Combination product | Bispectral Index (BIS) 40, Bispectral Index (BIS) 60 |
Primary outcome
To test the presence of implicit memory under two different planes of surgical general anesthesia in patients undergoing urologic (transurethral) or orthopedic (internal and external fixation) procedures
Time frame: 3 years
1 secondary outcome
To compare the pre and postoperative anxiety levels as a marker of clinical significance of operational implicit memory function.
Time frame: 3
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 7 Apr 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.
Mehmet S. Ozcan, MD principal investigator
University of Oklahoma
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing BIS 40 and BIS 60 in people with Anesthesia, General and Memory, run by University of Oklahoma 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 3 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: finished, as of the sponsor's last update on 7 Apr 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?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
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?
To test the presence of implicit memory under two different planes of surgical general anesthesia in patients undergoing urologic (transurethral) or orthopedic (internal and external fixation) procedures (time frame: 3 years). 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 7 Apr 2026.