Minimum Alveolar Concentrations of Sevoflurane for Maintaining Bispectral Index Below 50 in Morbidly Obese Patients

Study Overview
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Brief Summary
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the target of this study is to assess the minimum alveolar concentration of sevoflurane to maintain theBispectral Index below 50.The minimum alveolar concentration (MAC) for maintaining Bispectral Index below 50 (MACBIS50) of sevoflurane has been reported previously in adult with Body Mass Index ( BMI) < 40 to be 0.97 and in enfant to be 2.83%, However, there is no study assessed theBispectral Index below 50 (MACBIS50 ) in morbidly obese patient (BMI > 40). The first aim of our study is to assess the MACBIS50 of sevoflurane in morbidly obese patients BMI 40 - 70 using the Continuous Reassessment Method (CRM) in 80 % of patients.

Detailed Description
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After ethical committee approval and written informed consent, 30 morbidly obese adult patients , BMI 40- 70Kg/m², ASA physical status 1 and 2 , aged 18-49 yr, , undergoing elective bariatric surgery under general anesthesia using sevoflurane, were included in this study. Monitoring consisted of noninvasive blood pressure, Electrocardiogram (ECG) , pulse oximetry, and BIS. All subjects received a standard dose of 2 mcg/kg fentanyl approximately 20 min before induction of general anesthesia. a standard BIS® monitor strip was applied before fentanyl administration and induction of general anesthesia. Induction was performed in all patients with 2m/kg propofol, 0.2 mg/kg cisatracuruim, followed by direct laryngoscopy and tracheal intubation. Therefore, when BIS reached > 65 , sevoflurane was started immediately at the predetermined dose. The endtidal sevoflurane concentration was adjusted with starting dose for the first cohort patients 1% and maintained for 10 min to ensure equilibration with the cerebral anesthetic partial pressure followed by a 1-min assessment of BIS taken at 10-s intervals. Briefly, a first dose is given to the first patient and the next doses are given according to the following rule: if the subject responds positively (BIS<50), the dose is decreased one step for the next subject, and conversely, if the subject does not respond (BIS>50), the dose is increased one step. The dose adjustment is 0.2% for sevoflurane. The CRM is used to calculate the dose adjustment for every cohort with the number of patients for every cohort .

Official Title
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Minimum Alveolar Concentrations of Sevoflurane for Maintaining Bispectral Index Below 50 in Morbidly Obese Patients

Conditions
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Anesthesia

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: morbidly obese patient BMI 40-70 age : 20-40 year Exclusion Criteria: Age< 20 and > 40 BMI < 40 and > 70 comorbidity

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 40 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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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Morbidly obese patients<br>BMI 40-50 k/m2 | |
| Morbidly obese<br>BMI 50-60 k/m2 | |
| Morbidly obeses<br>BMI 60-70 k/m2 | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Minimal alveolar concentration of Sevoflurane for Maintaining BIS Below 50 |  | 24 hours |