The Effects of Horner's Syndrome Developing After Interscalene Brachial Plexus Block on Autonomic Nervous Activity

Study Overview
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Brief Summary
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This study evaluates the effects of Horner's syndrome on cardiac autonomic nervous activity after interscalene brachial plexus block. Cardiac autonomic nervous activity and bilateral pupil diameters will be measured in a scotopic light condition, 30 minutes after interscalene brachial plexus block under ultrasound guidance and 15 minutes after the subsequent sitting position.

Detailed Description
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Stellate ganglia provide sympathetic fibers to the heart. Ipsilateral stellate ganglion block accompanied by interscalene brachial plexus block causes Horner's syndrome presenting with miosis, ptosis, and anhidrosis. The extent of Horner's syndrome can be represented by the difference in pupil diameter between bilateral eyes. Cardiac autonomic nervous activity affected by stellate ganglion block can be measured by calculation of heart rate variability parameters.

Official Title
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The Effects of Difference in Pupil Size Between Bilateral Eyes on Cardiac Sympathetic Nervous Activity Following Interscalene Brachial Plexus Block

Conditions
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Brachial Plexus Block, Horner Syndrome, Autonomic Imbalance

Intervention / Treatment
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* Procedure: Interscalene brachial plexus block
* Drug: 0.75% ropivacaine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: American Society of Anesthesiologists physical status 1 Arthroscopic shoulder surgery under interscalene brachial plexus block Exclusion Criteria: Coagulopathy Infection at the site of brachial plexus block Peripheral neuropathy or neurologic sequelae on the operative limb Allergy to local anesthetics or history of allergic shock Psychiatric diseases Patient refusal Difficulty communicating with medical personnel Arrhythmias Ischemic heart disease Hypertension Diabetes mellitus Thyroid dysfunction Conduction abnormalities on electrocardiogram Electrolyte imbalance Medications affecting cardiac conduction Contralateral vocal cord palsy Contralateral hemidiaphragmatic paresis or paralysis Contralateral pneumothorax or hemothorax

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 60 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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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Interscalene brachial plexus block<br>Ultrasound-guided interscalene brachial plexus block with 25 ml to 30 ml of 0.75% ropivacaine | Procedure: Interscalene brachial plexus block<br>* Under ultrasound guidance, the 5th to 7th cervical nerve roots are identified between anterior and middle scalene muscles and subsequently blocked.<br>Drug: 0.75% ropivacaine<br>* Placement of 25 to 30 ml of 0.75% ropivacaine around the 5th to 7th cervical nerve roots<br>* Other names: Naropin;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Post-sitting sympathetic nervous activity | Natural-log transformed low frequency power of heart rate variability calculated using R wave to R wave intervals obtained for 5 minutes between 10 and 15 minutes after the sitting position following interscalene brachial plexus block | 15 minutes after the sitting position following interscalene brachial plexus block | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Post-sitting ipsilateral pupil diameter | Ipsilateral pupil diameter measured under a mesopic condition 15 minutes after the sitting position following interscalene brachial plexus block | 15 minutes after the sitting position following interscalene brachial plexus block | 
| Post-sitting contralateral pupil diameter | Contralateral pupil diameter measured under a mesopic condition 15 minutes after the sitting position following interscalene brachial plexus block | 15 minutes after the sitting position following interscalene brachial plexus block | 
| Post-anesthetic ipsilateral pupil diameter | Ipsilateral pupil diameter measured under a mesopic condition 30 minutes after interscalene brachial plexus block | 30 minutes after interscalene brachial plexus block | 
| Post-anesthetic contralateral pupil diameter | Contralateral pupil diameter measured under a mesopic condition 30 minutes after interscalene brachial plexus block | 30 minutes after interscalene brachial plexus block | 
| Pre-anesthetic ipsilateral pupil diameter | Ipsilateral pupil diameter measured under a mesopic condition 15 minutes after baseline acclimation | 15 minutes after baseline acclimation | 
| Pre-anesthetic contralateral pupil diameter | Contralateral pupil diameter measured under a mesopic condition 15 minutes after baseline acclimation | 15 minutes after baseline acclimation | 
| Post-sitting parasympathetic nervous activity | Natural-log transformed high frequency power of heart rate variability calculated using R wave to R wave intervals obtained for 5 minutes between 10 and 15 minutes after the sitting position following interscalene brachial plexus block | 15 minutes after the sitting position following interscalene brachial plexus block | 
| Post-sitting sympathovagal balance | Low-to-high frequency power ratio of heart rate variability obtained for 5 minutes between 10 and 15 minutes after the sitting position following interscalene brachial plexus block | 15 minutes after the sitting position following interscalene brachial plexus block | 
| Post-sitting overall variability of autonomic nervous system | Natural-log transformed total power of heart rate variability obtained for 5 minutes between 10 and 15 minutes after the sitting position following interscalene brachial plexus block | 15 minutes after the sitting position following interscalene brachial plexus block | 
| Post-anesthetic sympathetic nervous activity | Natural-log transformed low frequency power of heart rate variability between 25 and 30 minutes after interscalene brachial plexus block | Between 25 and 30 minutes after interscalene brachial plexus block | 
| Post-anesthetic parasympathetic nervous activity | Natural-log transformed high frequency power of heart rate variability between 25 and 30 minutes after interscalene brachial plexus block | Between 25 and 30 minutes after interscalene brachial plexus block | 
| Post-anesthetic sympathovagal balance | Low-to-high frequency power ratio of heart rate variability between 25 and 30 minutes after interscalene brachial plexus block | Between 25 and 30 minutes after interscalene brachial plexus block | 
| Post-anesthetic overall variability of autonomic nervous system | Natural-log transformed total power of heart rate variability between 25 and 30 minutes after interscalene brachial plexus block | Between 25 and 30 minutes after interscalene brachial plexus block | 
| Pre-anesthetic sympathetic nervous activity | Natural-log transformed low frequency power of heart rate variability 15 minutes after baseline acclimation | 15 minutes after baseline acclimiation | 
| Pre-anesthetic parasympathetic nervous activity | Natural-log transformed high frequency power of heart rate variability 15 minutes after baseline acclimation | 15 minutes after baseline acclimiation | 
| Pre-anesthetic sympathovagal balance | Low-to-high frequency power ratio of heart rate variability 15 minutes after baseline acclimation | 15 minutes after baseline acclimiation | 
| Pre-anesthetic overall variability of autonomic nervous system | Natural-log transformed total power of heart rate variability 15 minutes after baseline acclimation | 15 minutes after baseline acclimation | 
| Sensory blockade | C5 to T1 dermatomal blockade of the shoulder graded from 0 to 2 (0 = no cold sensation, 1 = reduced cold sensation, and 2 = normal cold sensation) by applying ice to the shoulder | 30 minutes after interscalene brachial plexus block | 
| Motor blockade | Motor blockade of the radial, ulnar, median, musculocutaneous, and axillary nerves graded from 0 to 2 (0 = no block 1 = partial block, and 2 = complete block) | 30 minutes after interscalene brachial plexus block | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Heart rate variability, Mesopic pupil size