Transesophageal Echocardiographic Evaluation of the Effect of Dexmedetomidine Infusion as an Adjuvant to General Anesthesia on the Cardiac Function

Study Overview
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Brief Summary
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Dexmedetomidine is a selective alpha-2 adrenergic agonist that can be considered as an adjuvant to propofol or inhalational anesthetics. Dexmedetomidine mediate its cardiovascular effect through activation of receptors in central and peripheral nervous system. The classic cardiovascular response of dexmedetomidine is the biphasic with initial short-term increase in blood pressure followed by long-lasting decrease in BP and HR. There were several reports about these hemodynamic changes of dexmedetomidine, but not the evaluation of direct effects on cardiac function. The purpose of this study is to evaluate the effects of dexmedetomidine as an anesthetic adjuvant on cardiac function by using the transesophageal echocardiography.

Conditions
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Anesthesia

Intervention / Treatment
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* Drug: Dexmedetomidine, Transesophageal echocardiography(TEE)
* Drug: Saline will be infused for 60 minutes at the same rates as dexmedetomidine group.


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Above 20 years of age. American Society of Anesthesiologists (ASA) Physical Status I, II, III. general anesthesia Exclusion Criteria: severe functional liver or kidney disease diagnosed HF ( NYHA class >3) arrhythmia or received treatment with antiarrythmic drug . severe bradycardia (HR < 45 bpm) and AV block pathologic esophageal lesion (esophageal stricture or varix ) pregnancy

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 80 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: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Dexmedetomidine group<br>Dexmedetomidine will be infused at a rate of 6 mcg/kg/hr for 10 minutes; resulting in a loading dose of 1 mcg/kg, followed by an infusion of 0.5 μg/kg/hr for 50 minutes. | Drug: Dexmedetomidine, Transesophageal echocardiography(TEE)<br>* Dexmedetomidine will be infused at a rate of 6 mcg/kg/hr for 10 minutes; resulting in a loading dose of 1 mcg/kg, followed by an infusion of 0.5 μg/kg/hr for 50 minutes.<br>* Other names: Precedex;|
| Placebo Comparator: Control group<br>Saline will be infused at a rate of 6 mcg/kg/hr for 10 minutes; resulting in a loading dose of 1 mcg/kg, followed by an infusion of 0.5 μg/kg/hr for 50 minutes. | Drug: Saline will be infused for 60 minutes at the same rates as dexmedetomidine group.<br> <br> * Other names: Saline;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| systolic function by TEE (fractional area change and ejection fraction) | Systolic function measured transesophageal echocardiographically by fractional area change and ejection fraction. | The participants will be followed for 1 hour after study drug is administered. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| diastolic function by TEE (ratio between early transmitral flow (E) and mitral annular tissue velocity (E') | Diastolic function measured transesophageal echocardiographically by ratio between early transmitral flow (E) and mitral annular tissue velocity (E'). | The participants will be followed for 1 hour after study drug is administered. |