Assessment of the C8 Dermatomal Block With Photoplethysmographic Amplitude After Interscalene Brachial Plexus Block

Study Overview
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Brief Summary
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The goal of this clinical trial is to investigate the effectiveness of photoplethysmographic amplitude in assessing the extent of anesthesia in the 8th cervical dermatome in patients undergoing interscalene brachial plexus block (ISBPB). The main question it aims to answer is Is there any difference in the post-block changes in photoplethysmographic amplitude measured from the ipsilateral 5th finger (supplied by the 8th cervical nerve root) between ISBPBs targeting the C5-to-C6 nerve roots and the C5-to-C8 nerve roots? Do the changes in photoplethysmographic amplitude represent the extent of anesthesia in the 8th cervical dermatome? Participants will receive either ISBPB targeting the C5-to-C6 nerve roots or the C5-to-C8 nerve roots, and then the changes in photoplethysmographic amplitude will be measured from the 5th finger ipsilateral to ISBPB.

Official Title
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Objective Assessment of Extent of Anesthesia in the 8th Cervical Dermatome Using Photoplethysmographic Amplitude in Patients Undergoing Interscalene Brachial Plexus Block

Conditions
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Brachial Plexus Block, Oximetry

Intervention / Treatment
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* Procedure: Interscalene brachial plexus block targeting the C5-to-C6 nerve roots
* Procedure: Interscalene brachial plexus block targeting the C5-to-C8 nerve roots


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: American Society of Anesthesiologists physical status 1 or 2 Schedule to receive interscalene brachial plexus block for arthroscopic shoulder surgery Exclusion Criteria: Coagulopathy Peripheral vascular diseases Arrhythmias Cardiac conduction abnormalities A history of medication affecting cardiac conduction Ischemic heart disease Hypertension Diabetes mellitus Thyroid dysfunction Other medical conditions affecting autonomic nervous activity Infection at the skin area for interscalene brachial plexus block Peripheral neuropathy or neurologic sequelae in the upper limb ipsilateral to the surgery Allergy to local anesthetics or a history of allergic shock Contralateral vocal cord palsy, hemidiaphragmatic paresis/paralysis or pneumo/hemo thorax Severe restrictive pulmonary disorder Electrolyte imbalance Difficulty in communicating with medical personnel Patients refusal

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: Diagnostic
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: C5-C6 group<br>The C5-to-C6 nerve roots and supraclavicular nerves are blocked with 25 ml of 0.75% ropivacaine under ultrasound guidance. | Procedure: Interscalene brachial plexus block targeting the C5-to-C6 nerve roots<br>* With the head rotated contralateral to interscalene brachial plexus block (ISBPB), the compactly arranged brachial plexus is visualized lateral to the pulsating subclavian artery under ultrasound guidance. The linear ultrasound transducer is moved cephalad until the C5-to-C8 nerve roots are visualized between the anterior and middle scalene muscles. A block needle is introduced from lateral to medial direction. A nerve root is blocked by placing at least 5 ml of 0.75% ropivacaine around it. The most caudal cervical nerve root (C6 nerve root) is blocked first, and the most cephalad one (C5 nerve root) is blocked last. Then, 3 ml of 0.75% ropivacaine is placed between the scalene and sternocleidomastoid muscles to block the supraclavicular nerves. An equivalent volume of a standard study drug is planned to be used (A total of 25 ml of 0.75% ropivacaine).<br>|
| Experimental: C5-C8 group<br>The C5-to-C8 nerve roots and supraclavicular nerves are blocked with 25 ml of 0.75% ropivacaine under ultrasound guidance. | Procedure: Interscalene brachial plexus block targeting the C5-to-C8 nerve roots<br>* With the head rotated contralateral to interscalene brachial plexus block (ISBPB), the compactly arranged brachial plexus is visualized lateral to the pulsating subclavian artery under ultrasound guidance. The linear ultrasound transducer is moved cephalad until the C5-to-C8 nerve roots are visualized between the anterior and middle scalene muscles. A block needle is introduced from lateral to medial direction. A nerve root is blocked by placing at least 5 ml of 0.75% ropivacaine around it. The most caudal cervical nerve root (C8 nerve root) is blocked first, and the most cephalad one (C5 nerve root) is blocked last. Then, 3 ml of 0.75% ropivacaine is placed between the scalene and sternocleidomastoid muscles to block the supraclavicular nerves. An equivalent volume of a standard study drug is planned to be used (A total of 25 ml of 0.75% ropivacaine).<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Time to achieve 50% of maximum photoplethysmographic amplitude measured from the 5th finger | During the whole study period, the photoplethysmographic waveform obtained from the 1st and 5th fingers ipsilateral to interscalene brachial plexus block is recorded at 100 Hz. The photoplethysmographic amplitude is calculated by subtracting the valley amplitude from the peak amplitude of one heartbeat in photoplethysmographic waveform. Using all the photoplethysmographic amplitudes between 0 and 25 minutes after the introduction of a block needle, a sigmoid Emax model is built. From the model, the time point, when 50% of maximum photoplethysmographic amplitude is achieved, can be derived. | 25 minutes after the introduction of a block needle | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Time to achieve 5% of maximum photoplethysmographic amplitude measured from the 5th finger | During the whole study period, the photoplethysmographic waveform obtained from the 1st and 5th fingers ipsilateral to interscalene brachial plexus block is recorded at 100 Hz. The photoplethysmographic amplitude is calculated by subtracting the valley amplitude from the peak amplitude of one heartbeat in photoplethysmographic waveform. Using all the photoplethysmographic amplitudes between 0 and 25 minutes after the introduction of a block needle, a sigmoid Emax model is built. From the model, the time point, when 5% of maximum photoplethysmographic amplitude is achieved, can be derived. | 25 minutes after the introduction of a block needle | 
| Time to achieve 10% of maximum photoplethysmographic amplitude measured from the 5th finger | During the whole study period, the photoplethysmographic waveform obtained from the 1st and 5th fingers ipsilateral to interscalene brachial plexus block is recorded at 100 Hz. The photoplethysmographic amplitude is calculated by subtracting the valley amplitude from the peak amplitude of one heartbeat in photoplethysmographic waveform. Using all the photoplethysmographic amplitudes between 0 and 25 minutes after the introduction of a block needle, a sigmoid Emax model is built. From the model, the time point, when 10% of maximum photoplethysmographic amplitude is achieved, can be derived. | 25 minutes after the introduction of a block needle | 
| Time to achieve 90% of maximum photoplethysmographic amplitude measured from the 5th finger | During the whole study period, the photoplethysmographic waveform obtained from the 1st and 5th fingers ipsilateral to interscalene brachial plexus block is recorded at 100 Hz. The photoplethysmographic amplitude is calculated by subtracting the valley amplitude from the peak amplitude of one heartbeat in photoplethysmographic waveform. Using all the photoplethysmographic amplitudes between 0 and 25 minutes after the introduction of a block needle, a sigmoid Emax model is built. From the model, the time point, when 90% of maximum photoplethysmographic amplitude is achieved, can be derived. | 25 minutes after the introduction of a block needle | 
| Time to achieve 95% of maximum photoplethysmographic amplitude measured from the 5th finger | During the whole study period, the photoplethysmographic waveform obtained from the 1st and 5th fingers ipsilateral to interscalene brachial plexus block is recorded at 100 Hz. The photoplethysmographic amplitude is calculated by subtracting the valley amplitude from the peak amplitude of one heartbeat in photoplethysmographic waveform. Using all the photoplethysmographic amplitudes between 0 and 25 minutes after the introduction of a block needle, a sigmoid Emax model is built. From the model, the time point, when 95% of maximum photoplethysmographic amplitude is achieved, can be derived. | 25 minutes after the introduction of a block needle | 
| Time to achieve 99% of maximum photoplethysmographic amplitude measured from the 5th finger | During the whole study period, the photoplethysmographic waveform obtained from the 1st and 5th fingers ipsilateral to interscalene brachial plexus block is recorded at 100 Hz. The photoplethysmographic amplitude is calculated by subtracting the valley amplitude from the peak amplitude of one heartbeat in photoplethysmographic waveform. Using all the photoplethysmographic amplitudes between 0 and 25 minutes after the introduction of a block needle, a sigmoid Emax model is built. From the model, the time point, when 99% of maximum photoplethysmographic amplitude is achieved, can be derived. | 25 minutes after the introduction of a block needle | 
| Time to achieve 5% of maximum photoplethysmographic amplitude measured from the 1st finger | During the whole study period, the photoplethysmographic waveform obtained from the 1st and 5th fingers ipsilateral to interscalene brachial plexus block is recorded at 100 Hz. The photoplethysmographic amplitude is calculated by subtracting the valley amplitude from the peak amplitude of one heartbeat in photoplethysmographic waveform. Using all the photoplethysmographic amplitudes between 0 and 25 minutes after the introduction of a block needle, a sigmoid Emax model is built. From the model, the time point, when 5% of maximum photoplethysmographic amplitude is achieved, can be derived. | 25 minutes after the introduction of a block needle | 
| Time to achieve 10% of maximum photoplethysmographic amplitude measured from the 1st finger | During the whole study period, the photoplethysmographic waveform obtained from the 1st and 5th fingers ipsilateral to interscalene brachial plexus block is recorded at 100 Hz. The photoplethysmographic amplitude is calculated by subtracting the valley amplitude from the peak amplitude of one heartbeat in photoplethysmographic waveform. Using all the photoplethysmographic amplitudes between 0 and 25 minutes after the introduction of a block needle, a sigmoid Emax model is built. From the model, the time point, when 10% of maximum photoplethysmographic amplitude is achieved, can be derived. | 25 minutes after the introduction of a block needle | 
| Time to achieve 50% of maximum photoplethysmographic amplitude measured from the 1st finger | During the whole study period, the photoplethysmographic waveform obtained from the 1st and 5th fingers ipsilateral to interscalene brachial plexus block is recorded at 100 Hz. The photoplethysmographic amplitude is calculated by subtracting the valley amplitude from the peak amplitude of one heartbeat in photoplethysmographic waveform. Using all the photoplethysmographic amplitudes between 0 and 25 minutes after the introduction of a block needle, a sigmoid Emax model is built. From the model, the time point, when 50% of maximum photoplethysmographic amplitude is achieved, can be derived. | 25 minutes after the introduction of a block needle | 
| Time to achieve 90% of maximum photoplethysmographic amplitude measured from the 1st finger | During the whole study period, the photoplethysmographic waveform obtained from the 1st and 5th fingers ipsilateral to interscalene brachial plexus block is recorded at 100 Hz. The photoplethysmographic amplitude is calculated by subtracting the valley amplitude from the peak amplitude of one heartbeat in photoplethysmographic waveform. Using all the photoplethysmographic amplitudes between 0 and 25 minutes after the introduction of a block needle, a sigmoid Emax model is built. From the model, the time point, when 90% of maximum photoplethysmographic amplitude is achieved, can be derived. | 25 minutes after the introduction of a block needle | 
| Time to achieve 95% of maximum photoplethysmographic amplitude measured from the 1st finger | During the whole study period, the photoplethysmographic waveform obtained from the 1st and 5th fingers ipsilateral to interscalene brachial plexus block is recorded at 100 Hz. The photoplethysmographic amplitude is calculated by subtracting the valley amplitude from the peak amplitude of one heartbeat in photoplethysmographic waveform. Using all the photoplethysmographic amplitudes between 0 and 25 minutes after the introduction of a block needle, a sigmoid Emax model is built. From the model, the time point, when 95% of maximum photoplethysmographic amplitude is achieved, can be derived. | 25 minutes after the introduction of a block needle | 
| Time to achieve 99% of maximum photoplethysmographic amplitude measured from the 1st finger | During the whole study period, the photoplethysmographic waveform obtained from the 1st and 5th fingers ipsilateral to interscalene brachial plexus block is recorded at 100 Hz. The photoplethysmographic amplitude is calculated by subtracting the valley amplitude from the peak amplitude of one heartbeat in photoplethysmographic waveform. Using all the photoplethysmographic amplitudes between 0 and 25 minutes after the introduction of a block needle, a sigmoid Emax model is built. From the model, the time point, when 99% of maximum photoplethysmographic amplitude is achieved, can be derived. | 25 minutes after the introduction of a block needle | 
| Baseline blood flow measured from the brachial artery ipsilateral to interscalene brachial plexus block | The linear ultrasound transducer is placed parallel with the brachial artery at the antecubital fossa. Using pulse wave Doppler ultrasound, time velocity integral per heartbeat is calculated. The cross-sectional diameter of the artery is measured with the transducer placed transversely to the artery. The blood flow of the artery (ml/min) is the product of the averaged time velocity integral (cm), cross-sectional area of the artery (cm2), and heart rate (beats/min). | 15 minutes before the introduction of a block needle | 
| Baseline blood flow measured from the radial artery ipsilateral to interscalene brachial plexus block | The linear ultrasound transducer is placed parallel with the radial artery at the distal forearm area. Using pulse wave Doppler ultrasound, time velocity integral per heartbeat is calculated. The cross-sectional diameter of the artery is measured with the transducer placed transversely to the artery. The blood flow of the artery (ml/min) is the product of the averaged time velocity integral (cm), cross-sectional area of the artery (cm2), and heart rate (beats/min). | 15 minutes before the introduction of a block needle | 
| Baseline blood flow measured from the ulnar artery ipsilateral to interscalene brachial plexus block | The linear ultrasound transducer is placed parallel with the ulnar artery at the distal forearm area. Using pulse wave Doppler ultrasound, time velocity integral per heartbeat is calculated. The cross-sectional diameter of the artery is measured with the transducer placed transversely to the artery. The blood flow of the artery (ml/min) is the product of the averaged time velocity integral (cm), cross-sectional area of the artery (cm2), and heart rate (beats/min). | 15 minutes before the introduction of a block needle | 
| Post-block blood flow measured from the brachial artery ipsilateral to interscalene brachial plexus block | The linear ultrasound transducer is placed parallel with the brachial artery at the antecubital fossa. Using pulse wave Doppler ultrasound, time velocity integral per heartbeat is calculated. The cross-sectional diameter of the artery is measured with the transducer placed transversely to the artery. The blood flow of the artery (ml/min) is the product of the averaged time velocity integral (cm), cross-sectional area of the artery (cm2), and heart rate (beats/min). | 25 minutes after the introduction of a block needle | 
| Post-block blood flow measured from the radial artery ipsilateral to interscalene brachial plexus block | The linear ultrasound transducer is placed parallel with the radial artery at the distal forearm area. Using pulse wave Doppler ultrasound, time velocity integral per heartbeat is calculated. The cross-sectional diameter of the artery is measured with the transducer placed transversely to the artery. The blood flow of the artery (ml/min) is the product of the averaged time velocity integral (cm), cross-sectional area of the artery (cm2), and heart rate (beats/min). | 25 minutes after the introduction of a block needle | 
| Post-block blood flow measured from the ulnar artery ipsilateral to interscalene brachial plexus block | The linear ultrasound transducer is placed parallel with the ulnar artery at the distal forearm area. Using pulse wave Doppler ultrasound, time velocity integral per heartbeat is calculated. The cross-sectional diameter of the artery is measured with the transducer placed transversely to the artery. The blood flow of the artery (ml/min) is the product of the averaged time velocity integral (cm), cross-sectional area of the artery (cm2), and heart rate (beats/min). | 25 minutes after the introduction of a block needle | 
| Sensory blockade of the C5 dermatome | Using an alcohol swab, the sensory blockade of each dermatome is graded as 0 (no cold sensation), 1 (reduced cold sensation), 2 (normal cold sensation). | 30 minutes after the introduction of a block needle | 
| Sensory blockade of the C6 dermatome | Using an alcohol swab, the sensory blockade of each dermatome is graded as 0 (no cold sensation), 1 (reduced cold sensation), 2 (normal cold sensation). | 30 minutes after the introduction of a block needle | 
| Sensory blockade of the C7 dermatome | Using an alcohol swab, the sensory blockade of each dermatome is graded as 0 (no cold sensation), 1 (reduced cold sensation), 2 (normal cold sensation). | 30 minutes after the introduction of a block needle | 
| Sensory blockade of the C8 dermatome | Using an alcohol swab, the sensory blockade of each dermatome is graded as 0 (no cold sensation), 1 (reduced cold sensation), 2 (normal cold sensation). | 30 minutes after the introduction of a block needle | 
| Sensory blockade of the T1 dermatome | Using an alcohol swab, the sensory blockade of each dermatome is graded as 0 (no cold sensation), 1 (reduced cold sensation), 2 (normal cold sensation). | 30 minutes after the introduction of a block needle | 
| Motor blockade of shoulder abduction | Motor blockade is assessed by rating the force of movement corresponding to each nerve as 0 (complete block), 1 (partial block), or 2 (no block). | 30 minutes after the introduction of a block needle | 
| Motor blockade of elbow flexion | Motor blockade is assessed by rating the force of movement corresponding to each nerve as 0 (complete block), 1 (partial block), or 2 (no block). | 30 minutes after the introduction of a block needle | 
| Motor blockade of forearm supination | Motor blockade is assessed by rating the force of movement corresponding to each nerve as 0 (complete block), 1 (partial block), or 2 (no block). | 30 minutes after the introduction of a block needle | 
| Motor blockade of forearm pronation | Motor blockade is assessed by rating the force of movement corresponding to each nerve as 0 (complete block), 1 (partial block), or 2 (no block). | 30 minutes after the introduction of a block needle | 
| Motor blockade of finger abduction | Motor blockade is assessed by rating the force of movement corresponding to each nerve as 0 (complete block), 1 (partial block), or 2 (no block). | 30 minutes after the introduction of a block needle | 
| Motor blockade of thumb abduction | Motor blockade is assessed by rating the force of movement corresponding to each nerve as 0 (complete block), 1 (partial block), or 2 (no block). | 30 minutes after the introduction of a block needle | 
| Motor blockade of thumb adduction | Motor blockade is assessed by rating the force of movement corresponding to each nerve as 0 (complete block), 1 (partial block), or 2 (no block). | 30 minutes after the introduction of a block needle | 
| Motor blockade of thumb opposition | Motor blockade is assessed by rating the force of movement corresponding to each nerve as 0 (complete block), 1 (partial block), or 2 (no block). | 30 minutes after the introduction of a block needle | 
| Baseline pupil diameter ipsilateral to interscalene brachial plexus block | Three minutes after the adaptation in low mesopic conditions, the pupil diameter is measured for 2 seconds at 30 Hz using a portable pupillometer. The pupil diameter is obtained by averaging 60 measurement values. | 5 minutes before the introduction of a block needle | 
| Baseline pupil diameter contralateral to interscalene brachial plexus block | Three minutes after the adaptation in low mesopic conditions, the pupil diameter is measured for 2 seconds at 30 Hz using a portable pupillometer. The pupil diameter is obtained by averaging 60 measurement values. | 5 minutes before the introduction of a block needle | 
| Post-block pupil diameter ipsilateral to interscalene brachial plexus block | Three minutes after the adaptation in low mesopic conditions, the pupil diameter is measured for 2 seconds at 30 Hz using a portable pupillometer. The pupil diameter is obtained by averaging 60 measurement values. | 35 minutes after the introduction of a block needle | 
| Post-block pupil diameter contralateral to interscalene brachial plexus block | Three minutes after the adaptation in low mesopic conditions, the pupil diameter is measured for 2 seconds at 30 Hz using a portable pupillometer. The pupil diameter is obtained by averaging 60 measurement values. | 35 minutes after the introduction of a block needle | 
| Pain upon a pinch at the skin area for posterior portal placement (1.5-3 cm inferior and medial to the posterolateral tip of the acromion) | The pain intensity is rated as 0 (no pain), 1 (mild pain), and 2 (severe pain). | 1 minute before the surgical incision | 
| Pain upon surgical incision (1.5-3 cm inferior and medial to the posterolateral tip of the acromion) | The pain intensity is rated as 0 (no pain), 1 (mild pain), and 2 (severe pain). | An average of 1 hour after the introduction of a block needle | 
| Pain upon posterior portal placement (1.5-3 cm inferior and medial to the posterolateral tip of the acromion) | The pain intensity is rated as 0 (no pain), 1 (mild pain), and 2 (severe pain). | 1 minute after surgical incision |