Propofol for Supreme LMA Insertion With and Without Remifentanil

Study Overview
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Brief Summary
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The aims of this study were to determine the clinically required concentration of propofol for LMA Supreme insertion, and to examine to what extent remifentanil reduces the dose of propofol and improves conditions for it's insertion.

Detailed Description
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The single-use Laryngeal Mask Airway SupremeTM (SLMA, Laryngeal Mask Company Limited, Singapore) is a new single use supraglottic airway device introduced recently that present combined features of the LMA ProSealTM (PLMA, Laryngeal Mask Company Limited) and the LMA FastrachTM (FLMA, Laryngeal Mask Company Limited). The mask has an anatomically shaped airway tube, elliptical in cross-section that facilitates easy insertion and minimizes accidental rotation. The cuff bowl is designed to prevent airway kinking and offer higher airway seal pressures around the laryngeal opening than the LMA ClassicTM (CLMA, Laryngeal Mask Company Limited) It has a drain tube that provides functional separation of the respiratory and digestive tracts to prevent gastric aspiration. Even though insertion of the SLMA is associated with a higher initial success rate, fewer airway manipulations and a safe and effective airway during anaesthesia, the anaesthetic techniques for its insertion were not standardised. Most available data on the requirements of anaesthetic drugs and co-induction agents used for insertion of SLMA originate from research involving other assessments of the SLMA such as the seal with respiratory and gastrointestinal tract.We tested for differences in the predicted concentration of propofol with and without remifentanil for insertion of the SLMA. Methods: 50 patients ASA class I or II aged 18-75 years undergoing ambulatory elective surgery will be randomized to one of two groups: those who receive propofol + saline (control group: n = 25) or propofol + remifentanil (propofol-remifentanil group: n=25). We will use target-controled infusions (Alaris®PK) for both drugs: propofol (Marsh et al.´s pharmacokinetic model) and remifentanil (Minto et al.´s pharmacokinetic model). The patients wil be premedicated with midazolam 1 mg iv before surgery. The target concentration for each patient was determined using the Dixon´s up-and-down method. Predetermined propofol and remifentanil blood and effect site concentrations were held constant for at least 10 min. After equilibration of plasma and effect site propofol concentrations, the SLMA will be inserted, and secured according to the manufacture´s recommendations, without the use of muscle relaxants. In control group, propofol concentrations will start at 4 μg ml-1, with 0,5 μg ml-1 as the step size, with the coadministration of saline. In propofol-remifentanil group, propofol + remifentanil at a target-controlled infusion 5 ng/mL will be coadministered. A single measurement will be obtained from each patient. If the patient reacted with movement, the propofol concentration for the next patient was increased by 0.5 μg ml-1 ±1 ; if there was no movement, it was decreased by 0.5 μg ml-1 ±1 . Movement was defined as bucking or gross purposeful muscular movement within 1 min of LMA insertion. Values of Cp 50 wil be determined by calculating the midpoint concentration after at least seven crossover points (movement/non movement) will be obtained in each group.

Official Title
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ED 50 of Propofol for Supreme LMA Insertion With and Without Remifentanil. A Randomized Trial

Conditions
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Patients Requiring Ambulatory Surgery Under General Anesthesia

Intervention / Treatment
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* Drug: propofol
* Drug: propofol and remifentanil


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: ASA II-II patients Scheduled to ambulatory surgery Need of general anaesthesia General anaesthesia usually performed with laryngeal mask Negative pregnancy test in women. Signed informed consent. Exclusion Criteria: Patients with a potentially difficult airway o (Mallampati III or IV, a limited mouth opening and/or cervical spine disease) Patients with reactive airway disease Signs of upper respiratory infection, Patients who had a risk of gastric aspiration
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

Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: propofol<br>In control group, propofol concentrations will start at 4 μg ml-1, with 0,5 μg ml-1 as the step size, with the coadministration of saline. | Drug: propofol<br> <br> |
| Experimental: propofol and remifentanil<br>In propofol-remifentanil group, propofol + remifentanil at a target-controlled infusion 5 ng/mL will be coadministered. | Drug: propofol and remifentanil<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The concentration of propofol with and without remifentanil for insertion of the SLMA | Comparison of he concentration of propofol with and without remifentanil for insertion of the SLMA | at insertion of SLMA | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| changes in Systolic Blood Pressure, Diastolic Blood Pressure and Heart Rate |  | basal and every 3 minutes until 6 minutes after insertion of the SLMA | 
| BIS | BIS data after SLMA insertion with both anaesthetic techniques | before and after SLMA insertion(every min until min 6) | 
| Fibrescope evaluation | Fibrescope evaluation of the SLMA Of the view of the glottis | after SLMA insertion | 
| blood pressure(Hypertension or hypotension) |  | before and after SLMA insertion(every min until min 6) | 
| heart rate (tachycardia or bradycardia) | tachycardia or bradycardia requiring treatment | before and after SLMA insertion(every min until min 6) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Laryngeal Mask Airway Supreme, propofol, remifentanil, effective dose of intravenous propofol, ED50