Changes in Pulse Wave Transit Time and Its Variability After Placement of Interscalene Brachial Plexus Block

Study Overview
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Brief Summary
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Pulse wave transit time (PWTT) increases due to decreased arterial vascular tone resulting from sympathetic blockade caused by regional anesthesia. Its oscillation (PWTT variability) also contains information on the interaction between autonomic nervous system and the cardiovascular system. The changes in PWTT and its variability have not been investigated in patients receiving interscalene brachial plexus block (ISBPB). It was hypothesized that ISBPB increases PWTT and reduces low frequency power of PWTT variability.

Official Title
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Changes in Pulse Wave Transit Time and Its Variability Measured From the Ipsilateral First Finger After Placement of Interscalene Brachial Plexus Block

Conditions
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Interscalene Brachial Plexus Block

Intervention / Treatment
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* Procedure: Interscalene brachial plexus block


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: American Society of Anesthesiologists status of 1 Scheduled to receive interscalene brachial plexus block for arthroscopic shoulder surgery Exclusion Criteria: Coagulopathy Infection of 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 Arrhythmias Cardiac conduction abnormalities A history of medication affecting cardiac conduction Ischemic heart disease Hypertension Diabetes mellitus Thyroid disfunction Other medical conditions affecting autonomic nervous activity

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 |
| --- | --- |
| ISBPB group<br>Interscalene brachial plexus block involving the C5 to C8 nerve roots | Procedure: Interscalene brachial plexus block<br>* Using a linear ultrasound transducer connected to an ultrasound machine, the compactly arranged brachial plexus is visualized lateral to the pulsating subclavian artery. The transducer is moved cephalad to visualize the 5th to 8th cervical (C5 to C8) nerve roots located between the anterior and middle scalene muscles. Using an in-plane technique, a block needle is inserted close to a nerve root in a lateral-to-medial direction. The needle is moved to place 0.75% ropivacaine around each nerve root. The C8 nerve root is blocked first, and the C5 nerve root is blocked last. After blocking the four cervical nerve roots, ropivacaine is placed in the intermuscular plane between the sternocleidomastoid and scalene muscles to block the supraclavicular nerves. A total of 26 ml of 0.75% ropivacaine is used for the interscalene brachial plexus block (6 ml per nerve root and 2 ml for the supraclavicular nerves).<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Natural-log-transformed low frequency power of pulse wave transit time variability | Calculated by integrating the power spectra of pulse wave transit time variability between 0.04 and 0.15 Hz. | Between 15 and 20 minutes after block needle insertion | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Natural-log-transformed low frequency power of pulse wave transit time variability | Calculated by integrating the power spectra of pulse wave transit time variability between 0.04 and 0.15 Hz. | During 5 minutes before the end of the acclimatization period | 
| Natural-log-transformed low frequency power of pulse wave transit time variability | Calculated by integrating the power spectra of pulse wave transit time variability between 0.04 and 0.15 Hz. | Between 5 and 10 minutes after block needle insertion | 
| Natural-log-transformed high frequency power of pulse wave transit time variability | Calculated by integrating the power spectra of pulse wave transit time variability between 0.15 and 0.4 Hz. | During 5 minutes before the end of the acclimatization period | 
| Natural-log-transformed high frequency power of pulse wave transit time variability | Calculated by integrating the power spectra of pulse wave transit time variability between 0.15 and 0.4 Hz. | Between 5 and 10 minutes after block needle insertion | 
| Natural-log-transformed high frequency power of pulse wave transit time variability | Calculated by integrating the power spectra of pulse wave transit time variability between 0.15 and 0.4 Hz. | Between 15 and 20 minutes after block needle insertion | 
| Pulse wave transit time | Time difference in milliseconds between the R peak of the electrocardiographic waveform and the peak of the 2nd-derivative photoplethysmographic waveform. | During 5 minutes before the end of the acclimatization period | 
| Pulse wave transit time | Time difference in milliseconds between the R peak of the electrocardiographic waveform and the peak of the 2nd-derivative photoplethysmographic waveform. | Between 5 and 10 minutes after block needle insertion | 
| Pulse wave transit time | Time difference in milliseconds between the R peak of the electrocardiographic waveform and the peak of the 2nd-derivative photoplethysmographic waveform. | Between 15 and 20 minutes after block needle insertion | 
| Sensory blockade | Assessed by grading the coldness with a 3-level scale consisting of 0 (no cold sensation), 1 (reduced cold sensation), and 2 (normal cold sensation) after applying an alcohol swab to the upper limb dermatomal areas innervated by the C5 to T1 nerve roots. | 20 minutes after block needle insertion | 
| Motor blockade | The muscle contraction power is rated as 0 (complete block), 1 (partial block), and 2 (no block) for shoulder abduction (axillary nerve), elbow flexion (musculocutaneous nerve), forearm supination (radial nerve), forearm pronation (median nerve), wrist extension (radial nerve), wrist flexion (median nerve), finger abduction (ulnar nerve), thumb abduction (radial nerve), thumb adduction (ulnar nerve), and thumb opposition (median nerve). | 20 minutes after block needle insertion | 
| Bilateral pupil diameters | Measured using a portable automated monocular infrared pupillometer (PLR-3000, NeurOptics Inc., Irvine, CA, the United States) at 30 Hz for 2 seconds. | Within 1 minute after acclimatization | 
| Bilateral pupil diameters | Measured using a portable automated monocular infrared pupillometer (PLR-3000, NeurOptics Inc., Irvine, CA, the United States) at 30 Hz for 2 seconds. | 20 minutes after block needle insertion | 
| Incidence of side effects related to interscalene brachial plexus block | Horner's syndrome, subjective dyspnea, and hoarseness | 20 minutes after block needle insertion |