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Intraoperative M-Entropy Measurements

This study has been completed.
Information provided by (Responsible Party):
University of Oklahoma Identifier:
First received: December 20, 2007
Last updated: April 12, 2017
Last verified: April 2017
The purpose of this study is to learn more about an Entropy monitor that the anesthesiologist will be using.

Condition Intervention
General Anesthesia Device: study cases

Study Type: Observational
Study Design: Observational Model: Case-Only
Time Perspective: Prospective
Official Title: Same-patient Reproducibility of Intraoperative M-Entropy Measurements

Resource links provided by NLM:

Further study details as provided by University of Oklahoma:

Primary Outcome Measures:
  • The investigators hypothesize that simultaneous M-Entropy measurements from the left and right side of the forehead of a person do not differ during general anesthesia. [ Time Frame: 1 year ]

Enrollment: 24
Study Start Date: September 2007
Study Completion Date: April 2009
Primary Completion Date: June 2008 (Final data collection date for primary outcome measure)
Groups/Cohorts Assigned Interventions
Study cases
Application of a second M-Entropy probe on the forehead of the patient; at the end the patient will have 2 probes on the forehead, one in the right and one in the left.
Device: study cases
Application of a second M-Entropy probe on the forehead of the patient, which will happen in the OR along with the application of other monitors immediately before induction of general anesthesia.
Other Name: M-entropy module (Datex-Ohmeda S/5 EntropyTM Module)

Detailed Description:

Depth of anesthesia monitors are increasingly used in clinical anesthesia practice. Bispectral Index (BIS) and M-Entropy are examples to these devices, both of which are available at our institution. Both BIS and M-Entropy use a unilateral, single channel of EEG to derive a number indicating the anesthetic depth. These devices have similar disposable skin probes that can be applied on either side of the forehead. Since the depth of anesthesia for an individual is the same over the whole brain cortex at a given point in time, BIS numbers obtained over the left and right side of the forehead should agree. The same should be true for M-Entropy as well.

A recent study, however, showed that two separate BIS probes, applied over the left and right forehead of the same patient at the same time, can give significantly different numbers. This has not been studied for M-Entropy. BIS and M-Entropy use different mathematical algorithms that process the raw EEG signal to compute a numeric value. Therefore, it is possible that M-Entropy may show different results in a similar study setup.

The aim is to investigate the same-patient reproducibility of M-Entropy by monitoring and recording Entropy variables over both the left and the right side of the forehead of patients under general anesthesia.


Ages Eligible for Study:   18 Years to 90 Years   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Sampling Method:   Non-Probability Sample
Study Population
Patients that are scheduled to have surgery under general anesthesia for which an intraoperative M-Entropy monitoring is planned. Suitable candidates will be identified by speaking to the attending anesthesiologists working at OU Presbyterian hospital.

Inclusion Criteria:

  • Patients scheduled to have surgery under general anesthesia, with a minimum of 60 minutes expected duration.

Exclusion Criteria:

  • Non-English speaker
  • Patients younger than 18 years of age
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT00599066

United States, Oklahoma
OU MEDICAL CENTER, Presbyterian Tower, OR
Oklahoma City, Oklahoma, United States, 73104
Sponsors and Collaborators
University of Oklahoma
Principal Investigator: Mehemet Ozcan, MD The University of Oklahoma Health Sciences Center, Department of Anesthesiology
  More Information

Responsible Party: University of Oklahoma Identifier: NCT00599066     History of Changes
Other Study ID Numbers: IRB No: 13577
Study First Received: December 20, 2007
Last Updated: April 12, 2017
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No

Keywords provided by University of Oklahoma:
M-Entropy processed this record on August 16, 2017