Reduction in MACbar of Sevoflurane by Dexmedetomidine in Children

Study Overview
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Brief Summary
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The study was designed to define the interaction of intravenous infusion of dexmedetomidine, an a2-adrenergic agonist, and sevoflurane in children having surgery by using the minimum alveolar concentration which can block adrenergic and cardiovascular responses to incision(MACbar) of sevoflurane as the measure of anesthetic potency.

Detailed Description
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The investigators observed the effects of different doses of dexmedetomidine on the minimum alveolar concentration of sevoflurane to blockade adrenergic response to surgical incision in 50% of children (MACBAR). And to explore the safety of use of dexmedetomidine in pediatric patients.

Official Title
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Dexmedetomidine Augments Block of Sympathetic Responses to Skin Incision During Sevoflurane Anesthesia in Children

Conditions
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Children

Intervention / Treatment
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* Drug: dexmedetomidine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: aged 2 to 6 yr American Society of anesthesiologists I or II scheduled to have general anesthesia and to have skin incisions on the abdomen Exclusion Criteria: anemia or abnormal preoperative electrolyte concentrations a history of cardiovascular or central nervous system diseases a history of pulmonary disease known hepatic or renal disease a body weight exceeding 50% of the upper limit of ideal body weight for height taking drugs with cardiovascular or central nervous system effects use of any experimental drug within the past 30 days allergy to any drug that may be administered during the study exposure to general anesthesia within the previous 7 days second- or third-degree atrioventricular block taking drugs preoperatively that would interfere with MAC determination(e.g.,opioids or sedatives)

Ages Eligible for Study
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Minimum Age: 2 Years
Maximum Age: 6 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

Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| No Intervention: control group<br>children undergoing selective lower abdominal surgery received saline before induction | |
| Experimental: D1 group<br>children undergoing selective lower abdominal surgery received a bolus dose of 0.5 µg/kg dexmedetomidine followed by a continuous infusion of 0.5 µg/kg /h before induction | Drug: dexmedetomidine<br>* children received intravenous infusion with a bolus dose dexmedetomidine and followed by a continuous infusion before induction. use sevoflurane for induction and a steady-state end-tidal sevoflurane concentration was maintained for at least 15 min before skin incision.<br>* Other names: precedex;|
| Experimental: D2 group<br>children undergoing selective lower abdominal surgery received a bolus dose of 1.0µg/kg dexmedetomidine followed by a continuous infusion of 1.0 µg/kg /h before induction | Drug: dexmedetomidine<br>* children received intravenous infusion with a bolus dose dexmedetomidine and followed by a continuous infusion before induction. use sevoflurane for induction and a steady-state end-tidal sevoflurane concentration was maintained for at least 15 min before skin incision.<br>* Other names: precedex;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| the end-tidal sevoflurane concentration to blockade adrenergic response to surgical incision in 50% of children (MACBAR) | A predetermined steady-state end-tidal sevoflurane concentration(4%) was maintained for at least 15 min before skin incision.we observed the change in Mean Blood Pressure or Heart rate to determined the next end-tidal sevoflurane concentration.Followed the modified Dixon up and down method to obtain MACBAR of every child.The MACBAR of sevoflurane and its 95% confidence interval were calculated by Sum Average method. | at once before incision and 5 min period after incision | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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dexmedetomidine, sevoflurane, MAC bar, drug interaction, anesthesia