Perfusion Index for Predicting Brachial Plexus Block Success Under General Anesthesia

Study Overview
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Brief Summary
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This study was designed to determine whether the success or failure of interscalene brachial plexus block under general anesthesia can be predicted using perfusion index (PI).

Detailed Description
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The success of peripheral nerve blocks is usually evaluated by assessment of sensory and motor function; however, this method cannot be applied in the patient who has uncheckable mental status, e.g. general anesthesia, or who is uncommunicable, e.g. different language user. The perfusion index (PI) is a numerical value for the ratio between pulsatile and non-pulsatile blood flow measured by a special pulse oximeter, and PI had been proved as a useful tool for evaluation of successful supraclavicular nerve block in awake patients as an objective method. With the use of ultrasound guidance in skilled hands, it is a reasonable option to perform neuraxial and peripheral regional blocks in sedated or anesthetized patients. However, there has been no evidence of applying PI for predicting the success of nerve block in general anesthetized patients.

Official Title
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Usefulness of Pulse Oximeter Perfusion Index for Predicting the Success of Interscalene Brachial Plexus Blockade Under General Anesthesia

Conditions
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Disorder of Shoulder

Intervention / Treatment
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* Procedure: Interscalene brachial plexus blocks with ultrasound guidance under general anesthesia


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 20-70 years old, BMI 20-35 kg.m-2, elective shoulder surgery, ASA physical status I-III Exclusion Criteria: refusal of the patient, comorbid with serious vascular disease, diabetes, allergy to local anesthetics, patients on regular opioids, peripheral neuropathy.

Ages Eligible for Study
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Minimum Age: 20 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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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| BPB success<br>The study included patients aged between 20 and 70 yr who are to undergo elective shoulder surgery under general anesthesia. Patients undergo general anesthesia induction before the interscalene block is performed. Ultrasound-guided interscalene brachial plexus block will be performed in anesthetized patients before surgery. PI monitor will be applied to both blocked and non-blocked limbs using two separate oximeters. And the SUCCESS (or failure) of the block will be confirmed by (1) 30% change of heart rate and blood pressure after incision during operation, and (2) pain score, motor and sensory function test after surgery in the post-anesthesia recovery unit. | Procedure: Interscalene brachial plexus blocks with ultrasound guidance under general anesthesia<br>* Ultrasound-guidance, interscalene brachial plexus blocks, in-plane technique, perineural injection, 0.5% ropivacaine 12.5ml and 0.2% lidocaine 12.5ml<br>|
| BPB failure<br>The study included patients aged between 20 and 70 yr who are to undergo elective shoulder surgery under general anesthesia. Patients undergo general anesthesia induction before the interscalene block is performed. Ultrasound-guided interscalene brachial plexus block will be performed in anesthetized patients before surgery. PI monitor will be applied to both blocked and non-blocked limbs using two separate oximeters. And the (success or) FAILURE of the block will be confirmed by (1) 30% change of heart rate and blood pressure after incision during operation, and (2) pain score, motor and sensory function test after surgery in the post-anesthesia recovery unit. | Procedure: Interscalene brachial plexus blocks with ultrasound guidance under general anesthesia<br>* Ultrasound-guidance, interscalene brachial plexus blocks, in-plane technique, perineural injection, 0.5% ropivacaine 12.5ml and 0.2% lidocaine 12.5ml<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Perfusion Index | perfusion index measured applied to both blocked and non-blocked limbs using two separate oximeters | change between before and 15 minutes after brachial plexus block | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Heart rate | heart rate in bpm during operation | change between before and 5 minutes after incision of surgical procedure | 
| Blood pressure | blood pressure in mmHg during operation | change between before and 5 minutes after incision of surgical procedure | 
| Pain score | Numeric rating scale for pain on a 0-10 scale where 0=no pain and 10=unbearable pain | 1 hour after surgery | 
| Sensory function test on supraclavicular nerve and axillary nerve | 0-2 scale where 0=no block; 1=analgesia (patient can feel touch, not cold); 2=anesthesia (patient cannot feel touch) | 1 hour after surgery | 
| Motor function test on supraclavicular nerve and axillary nerve and | 0-2 scale where 0 = no block; 1 = paresis; 2 = paralysis | 1 hour after surgery |