Regional Changes in Upper Limb Perfusion Following Brachial Plexus Block: A Pilot Study

Study Overview
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Brief Summary
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Ultrasound-guided regional anesthesia is increasingly being used in the modern surgical environment to provide specific intraoperative anesthesia and postoperative analgesia. Infiltration of local anesthesics around peripheral nerves firs blocks sympathetic, then sensory, then motor nerve function. Sympathectomy-induced vasodilation following brachial plexus block results in increased skin temperature and arterial flow within minutes. Although it has not been shown to reliably increase diameter or cross-sectional area of distal arteries, brachial plexus block does change the pattern and quantity of blood flow to the hand. Given that the magnitude of change of flow cannot be attributed to vessel radius, the investigators suspect that the more laminar fluid dynamics are due to vascular tone. The investigators study aims to quantify alterations in physiology and peripheral vasodilator response. The investigators anticipate that axially block will significantly improve regional blood flow.

Official Title
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Regional Changes in Upper Limb Perfusion Following Brachial Plexus Block: A Pilot Study

Conditions
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Anesthesia, Conduction, Nerve Block, Sympathectomy, Regional Blood Flow

Intervention / Treatment
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* Other: Monitoring


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: ASA physical status I, II, III BMI less than or equal to 39 Presenting for elective upper limb surgery Does not meet any exclusion criteria Exclusion Criteria: Age over 80 ASA physical status IV or V BMI greater or equal to 40 Language barrier precluding ability to give informed consent History of coagulopathy INR < 1.4 Platelet count < 100 Allergy to local anesthetics Known peripheral vascular disease of the upper limbs Amputation of one or both upper limbs, not including digits Peripheral neurological disease Does not consent to participate in study

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 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 |
| --- | --- |
| Patients<br> | Other: Monitoring<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in regional blood flow and perfusion characteristics in the upper arm arteries from baseline to 20 minutes after unilateral axillary block. | Physiologic parameter | 30 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in the caliber of the arteries of the arm between arms from baseline to 20 minutes after unilateral axillary block. | Physiologic parameter | 30 minutes | 
| Changes in skin temperature between hands from baseline to 20 minutes after unilateral axillary block. | Physiologic parameter | 30 minutes | 
| Sensory loss in radial, ulnar, and median nerve distribution between hands from baseline to 20 minutes after unilateral axillary block. | Physical examination | 30 minutes | 
| Motor weakness in radial, ulnar, and median nerve distributions between hands from baseline to 20 minutes after unilateral axillary block | Physical examination | 30 Minutes |