Dexmedetomidine on Optic Nerve Sheath Diameter

Study Overview
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Brief Summary
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Dexmedetomidine, might attenuate the sympathetic activation and contribute to stable hemodynamics. The investigator hypothesized that continuous infusion of dexmedetomidine during laparoscopic lower abdominal surgery, might help to attenuate the increment of intracranial pressure and the investigator would observe the optic nerve sheath diameter using ultrasonography.

Detailed Description
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Laparoscopic lower abdominal surgery requires the Trendelenburg position with pneumoperitoneum for a prolonged time, but this can cause significant increase in intracranial pressure. Dexmedetomidine, a selective alpha2 receptor agonist might attenuate the sympathetic activation and contribute to stable hemodynamics. The investigator hypothesized that continuous infusion of dexmedetomidine during laparoscopic lower abdominal surgery, might help to attenuate the increment of intracranial pressure and the investigator would observe the optic nerve sheath diameter using ultrasonography.

Official Title
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Effect of Dexmedetomidine on Optic Nerve Sheath Diameter During Laparoscopic Anterior Resection

Conditions
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Intracranial Hypertension

Intervention / Treatment
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* Drug: Dexmedetomidine
* Drug: normal saline


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: clinical diagnosis of colorectal cancer planed for laparoscopic low anterior resection Exclusion Criteria: morbid obesity (body mass index > 30 kg.m-2) history of cerebrovascular disease history of respiratory disease uncontrolled cardiovascular disease

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 65 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

Primary Purpose: Supportive Care
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Control<br>Infusion of normal saline | Drug: normal saline<br>* infusion of normal saline<br>* Other names: NS;|
| Active Comparator: Dexmedetomidine<br>infusion of dexmedetomidine 0.5ug/kg/h for 10 min and after that, infusion of dexmedetomidine 0.4ug/kg/h until the end of surgery | Drug: Dexmedetomidine<br>* infusion of dexmedetomidine 0.5ug/kg/h for 10 min and after that, infusion of dexmedetomidine 0.4ug/kg/h until the end of surgery<br>* Other names: dex;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Optic nerve sheath diameter | mm | Change from Baseline optic nerve sheath diameter at pneumoperitoneum 30 min | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Respiratory and mean arterial pressure | mmHg | Change from Baseline Respiratory and mean arterial pressure at pneumoperitoneum 30 min |