Dosage of Mepivacaine in Ultrasound Axillary Block

Study Description

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Brief Summary:

The use of ultrasonography as an adjunct to regional anesthesia has significantly increased in recent years. Brachial plexus blockade by an axillary approach is amenable to the use of ultrasound guidance. Real time sonography of nerve structures ensures an optimal distribution of the block solution. When compared to other methods of nerve localization, sonography decreases: failure rate procedure time and the onset time for blockade. Furthermore, the use of ultrasound for peripheral nerve blockade demonstrates decreased procedure related complications such as nerve injury and unintentional vascular puncture.

Traditional axillary block techniques relying on surface anatomical landmarks require large volumes of local anesthetic, generally 40mL and greater. Utilizing the increased accuracy offered by ultrasound, some studies have shown that low volumes of local anesthetic can yield successful axillary plexus blockade. Therefore, the tradition of using large volumes of local anesthetic for axillary blocks, even without ultrasound, may not be warranted.

Although recent investigations support using a low volume of local anesthetic for brachial plexus blockade, there is a lack of outcome data from blinded randomised trials. The primary objective of this study was to evaluate 2 different volumes of local anesthetic for axillary blockade: 1) 20mL or 2) 30 mL. For the 2 different volumes used in this study, a 1.5% solution of mepivacaine was chosen due to its widespread clinical use in axillary blocks, which is secondary to: rapid onset of action, intermediate duration of effect, and relative low cost. The primary outcome was block success rate for outpatients undergoing distal upper limb surgery. Secondary objectives included comparing the 2 volumes with respect to: time required to perform the block, and onset of sensory and motor blockade.

Condition or disease	Intervention/treatment	Phase
Nerve Block; Neuromuscular Blockade; Anesthesia	Drug: Mepivacaine	Not Applicable

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Study Design

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Study Type :	Interventional (Clinical Trial)
Actual Enrollment :	64 participants
Intervention Model:	Single Group Assignment
Masking:	Triple (Participant, Investigator, Outcomes Assessor)
Primary Purpose:	Treatment
Official Title:	Effective Low Dosage of Mepivacaine in Ultrasound Guided Axillary Block in Patients Undergoing Distal Upper Extremity Surgery
Study Start Date :	April 2010
Actual Primary Completion Date :	August 2010
Actual Study Completion Date :	September 2010

Arms and Interventions

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Study Description Study Design Arms and Interventions Outcome Measures Eligibility Criteria Contacts and Locations More Information

Arm	Intervention/treatment
Experimental: Mepivacaine, Ultrasound Axillary Block; Group 1) 20mL 1.5% mepivacaine Group 2) 30mL 1.5% mepivacaine	Drug: Mepivacaine; Group 1) 20mL 1.5% mepivacaine, one dose Group 2) 30mL 1.5% mepivacaine, one dose

Outcome Measures

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Primary Outcome Measures :

1. Successful Block [ Time Frame: 30 minutes ]

   Definitions of successful block Functional successful block: Sensory score of 0-1 in all 4 territories and motor score of 0-1 in 3 of 4 territories within 30 minutes of needle extraction.

   Surgical successful block: no required intraoperative supplemental local anesthetic, light sedation <25mcg/kg/min propofol and absence of general endotracheal anesthesia.

Secondary Outcome Measures :

1. Time required until onset of sensory blockade. [ Time Frame: 30 minutes ]

   Onset of Sensory blockade: Examined every 5 minutes following needle extraction using a blunt needle at 4 specific anatomic locations corresponding to radial, ulnar, median, and musculocutaneous distributions and compared with contralateral side using same stimulus.

   Onset of Motor Blockade: Examined every 5 minutes following needle extraction. Wrist flexion: median nerve; wrist extension: radial nerve; abduction of 5th finger or straight finger adduction: ulnar nerve; elbow flexion (with forearm supinated): musculocutaneous nerve.

2. Time taken until Onset of Motor Blockade [ Time Frame: 30 minutes ]
   Onset of Motor Blockade: Examined every 5 minutes following needle extraction. Wrist flexion: median nerve; wrist extension: radial nerve; abduction of 5th finger or straight finger adduction: ulnar nerve; elbow flexion (with forearm supinated): musculocutaneous nerve.

Eligibility Criteria

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Ages Eligible for Study:	18 Years to 80 Years (Adult, Senior)
Sexes Eligible for Study:	All
Accepts Healthy Volunteers:	Yes

Criteria

Inclusion Criteria:

• Orthopedic forearm, wrist and hand surgery
• ASA I-III
• block procedure time less than 6 minutes
• pre-block sedation using less than 2 mcg fentanyl and less than .04 mg midazolam,
• patient consent to light pre-op sedation

Exclusion Criteria:

• Elbow/arm surgery longer than 2 hours
• ASA IV
• BMI greater than 35
• Pregnant patients
• history of CVA or scarring in the axillary to elbow area
• history of neurological impairment of either upper extremity
• Any allergies to local anesthetics coagulopathy,
• infection at the site of block
• patients requiring opioid therapy for chronic pain

Contacts and Locations

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Sponsors and Collaborators

Wayne State University

Investigators

Principal Investigator:	Samuel Perov, M.D.	Wayne State University, Department of Anesthesiology

More Information

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Study Description Study Design Arms and Interventions Outcome Measures Eligibility Criteria Contacts and Locations More Information

Responsible Party:	Samuel Perov, Dr Samuel Perov, Wayne State University
ClinicalTrials.gov Identifier:	NCT01485653 History of Changes
Other Study ID Numbers:	WSU irb# 0902006824; need to get ( Other Identifier: WSU IRB )
First Posted:	December 5, 2011
Last Update Posted:	December 8, 2011
Last Verified:	December 2011

Keywords provided by Samuel Perov, Wayne State University:

Brachial Plexus; Mepivacaine; Ultrasound; Axillary; Block

Additional relevant MeSH terms:

Mepivacaine; Anesthetics, Local; Anesthetics; Central Nervous System Depressants	Physiological Effects of Drugs; Sensory System Agents; Peripheral Nervous System Agents