Depth of Anesthesia on Implicit Memory

Study Overview
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Brief Summary
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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
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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).

Official Title
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The Effect of Depth of Anesthesia on Implicit Memory

Conditions
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Anesthesia, General, Memory

Intervention / Treatment
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* Combination Product: BIS 40
* Combination Product: BIS 60


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Persons signing informed consent Elective general surgery for orthopedics (external or internal fixation) or urologic (transurethral) Literate Native English speaking Exclusion Criteria: Hearing impaired History of cognitive dysfunction Subjects requiring post-operative sedation for any indication

Ages Eligible for Study
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Minimum Age: 55 Years
Maximum Age: 90 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Supportive Care
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Bispectral Index (BIS) 40<br>Target BIS 40 | Combination Product: BIS 40<br>* 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.<br>* Other names: Audio File;Combination Product: BIS 60<br>* 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.<br>* Other names: Audio File;|
| Experimental: Bispectral Index (BIS) 60<br>Target BIS 60 | Combination Product: BIS 40<br>* 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.<br>* Other names: Audio File;Combination Product: BIS 60<br>* 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.<br>* Other names: Audio File;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| 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 |  | 3 years | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| To compare the pre and postoperative anxiety levels as a marker of clinical significance of operational implicit memory function. |  | 3 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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elective surgery, general anesthesia, implicit memory