Cervical Vagus Nerve Block Prevents Ocularvagal Reflex

Study Overview
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Brief Summary
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In ophthalmic surgery, surgical operations such as pulling certain eye tissues or compressing the eyeball often leads to bradycardia, arrhythmia even cardiac arrest, bradypnea, nausea and vomiting and elevated blood sugar level. The condition is called the ocularvagal reflex (OVR). Traditionally, when the bradycardia or arrhythmia happens, the operation has to be suspended, and atropine or isoproterenol is given intravenously to treat the bradycardia. Vagus nerve block may be an effective way to prevent and alleviate this vagal reflex. However it is difficult to perform the nerve block with anatomical landmark (blind) methods. In this study, the investigators used ultrasound-guided right cervical vagus nerve block to reduce the incidence of the OVR. The researchers hypothesized that low concentrations of lidocaine or ropivacaine can block the right cervical vagus nerve and reduce the incidence of intraoperative OVR. Researchers evaluated the changes of heart rate, blood pressure, oxygen saturation, and airway pressure in patients undergoing high-risk OVR surgery.

Official Title
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Ultrasound-guided Cervical Vagus Nerve Block Prevents Ocularvagal Reflex in Ophthalmic Surgery

Conditions
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Reflex, Oculocardiac

Intervention / Treatment
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* Procedure: Ultrasound guided vagus nerve block
* Drug: Bradycardia Treatment


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients received surgeries with high-risk OVR, including the strabismus surgery, the posterior scleral reinforcement, and the insertion of ocular implant. Exclusion Criteria: Those who have pre-existed vocal cord damage before surgery (such as hoarseness, electronic laryngoscopy shows fixed vocal cords or arytenoid cartilage dislocation). Those with a history of surgery on the both sides of the neck (eg, thyroidectomy, carotid endarterectomy). American Society of Anesthesiologist (ASA) Grade > 3 Patients with infection at the neck puncture site, or severe coagulation abnormalities before surgery, or a history of local anesthetic allergy, or who have a pacemaker.

Ages Eligible for Study
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Minimum Age: 16 Years
Maximum Age: 70 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: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Sham Comparator: Control group<br>Conventional monitor and treatment The surgery is performed after patient is under general anesthesia. If patient's heart rate significantly slows down or bradycardia/arrhythmia happens, the surgeon will be asked to suspend the operation. Meanwhile, atropine (0.01-0.02mg/kg) is given intravenously to increase the heart rate. If atropine fails to increase the heart rate, isoproterenol (1-2 μg/per time) will be given intravenously to increase the heart rate. | Drug: Bradycardia Treatment<br>* If the OVR happens because the surgical stimulation, the operation suspends and atropine (0.01-0.02mg/kg) or isoproterenol (1-2 μg/per time)is given intravenously to increase the heart rate.<br>|
| Experimental: Nerve block group<br>After the patient is under general anesthesia, an attending physicians perform the ultrasound-guided cervical vagus nerve block (using a 50mm Braun nerve stimulation needle, and the patients were injected with 10ml of lidocaine or ropivacaine ). Then the operation starts. If patient's heart rate significantly slows down or bradycardia/arrhythmia happens, the surgeon will be asked to suspend the operation. Meanwhile, atropine (0.01-0.02mg/kg) is given intravenously to increase the heart rate. If atropine fails to increase the heart rate, isoproterenol (1-2 μg/per time) will be given intravenously to increase the heart rate. After endotracheal tube is removed, the patient will be followed up for next 24 hours. | Procedure: Ultrasound guided vagus nerve block<br>* Before the operation starts, patients received the ultrasound guided vagus nerve block. A 50mm Braun nerve stimulation needle is guided by the ultrasonic beam to insert into the carotid sheath and 10ml of lidocaine or ropivacaine is injected.<br>Drug: Bradycardia Treatment<br>* If the OVR happens because the surgical stimulation, the operation suspends and atropine (0.01-0.02mg/kg) or isoproterenol (1-2 μg/per time)is given intravenously to increase the heart rate.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes of heart rate | Changes of heart rate in beat per minute from Baseline | during the operation | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes of Blood pressure | Changes of systolic blood pressure in mmHg from Baseline | during the operation | 
| Changes of Peak airway pressure | Changes of Blood pressure in mmHg from Baseline | during the operation | 
| Changes of SpO2 | Changes of SpO2 in percentage in mmHg from Baseline | during the operation | 
| Nausea and vomiting in times |  | 24 hours after the operation | 
| Voice changes in grades (0-3) | Changes of Voice changes in grades (0-3) from Baseline. 0 means good, 2 means moderate change of voice, 3 means hoarse voice | 24 hours after the operation |