Minimum Effective Volume of Ropivacaine 7.5 mg/ml for the Lateral and Sagittal Infraclavicular Brachial Plexus Block

Minimum Effective Volume of Ropivacaine 7.5 mg/ml for the Lateral and Sagittal Infraclavicular Brachial Plexus Block When Using Guidance by Both Ultrasound and Nerve Stimulation.

Systemic LA toxicity is an important complication of regional anesthesia. Lowering the LA dose is one of the strategies to reduce this risk. For upper limb blocks it is well documented that ultrasound guidance allows a significant lower dose of LA for interscalene and axillary blocks than with guidance by peripheral nerve stimulation. However, a corresponding difference has not yet been found for supraclavicular and infraclavicular blocks. The aim of the present study is to define the minimum effective volume of ropivacaine 7.5 mg/ml when using the LSIB method.

Study Overview

• Status: Completed
• Conditions: Pain
• Intervention / Treatment: Drug: Ropivacaine

Detailed Description

The blocks will be performed as previously described, by an anesthesiologist with LSIB expertise. The lateral, medial and posterior cords are the target of infra-clavicular brachial plexus blocks. During a prescan we will record if they can be visualized by ultrasound and indicate their positions periarterially. The deep location of the cords may hamper their identification, especially that of the medial cord. We describe the cord positions with reference to the short-axis (cross-sectional) view of the axillary artery, which is compared to a clockface having 12 o'clock ventrally. In a former MRI study it was found that the cords were usually located in a sector from 3-11 o'clock (the 3-11 sector) and within a distance of 2 cm from the midaxis of the axillary artery. The point closest to the cords was at 8 o'clock, immediately outside the arterial wall. Point of needle insertion is at the intersection between the lower edge of the clavicle and the medial surface of the coracoid process. We direct the needle tip to the 8 o'clock position and observe the spread of LA from this position. On demand we adjust the needle position to secure a complete fill of the 3-11 sector with LA (multiple injections).

The block needle has an electrical cable. Prior to LA injections we test if a minimal electric output (0.2 mA/0.1 msec duration) elicits a motor response. If such a response is obtained, the needle is withdrawn (in steps of 1 mm), until the motor response disappears. This is to reduce the risk of intraneural injection.

• Study Type: Interventional
• Enrollment (Anticipated): 25
• Phase: Phase 4

Contacts and Locations

Study Locations

• Norway
  • Troms
    • Tromsø, Troms, Norway, 9038
      • University Hospital of North Norway

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 65 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Patients of American Society of Anesthesiologists physical status (ASA) I-II
• Scheduled for surgery distal to the elbow.
• Duration of surgery >1 hour.
• Age 18-65 years,
• Body mass index 20-35 kg/m2

Exclusion Criteria:

• Pregnancy
• Any contraindication to regional anesthesia
• Patients on major opioids because of chronic pain
• Atrioventricular block
• Pacemaker
• Diabetes
• Peripheral neuropathy

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: Single

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
The primary outcome measure is the minimum effective volume of ropivacaine 7.5 mg/ml providing a successful infraclavicular block (LSIB) in 50% of the patients (MEAV50).	30 minutes

Collaborators and Investigators

• Sponsor: University Hospital of North Norway
• Investigators: Principal Investigator: Lars M Ytrebo, Professor, University Hospital of North Norway

Study record dates

Study Major Dates

• Study Start: February 1, 2012
• Primary Completion (Actual): June 1, 2012
• Study Completion (Actual): July 1, 2012

Study Registration Dates

• First Submitted: December 14, 2011
• First Submitted That Met QC Criteria: December 15, 2011
• First Posted (Estimate): December 16, 2011

Study Record Updates

• Last Update Posted (Estimate): September 11, 2012
• Last Update Submitted That Met QC Criteria: September 9, 2012
• Last Verified: September 1, 2012

More Information

Terms related to this study

• Keywords: Ropivacaine; Brachial plexus
• Additional Relevant MeSH Terms: Physiological Effects of Drugs; Central Nervous System Depressants; Peripheral Nervous System Agents; Sensory System Agents; Anesthetics; Anesthetics, Local; Ropivacaine
• Other Study ID Numbers: UNorthNorway (UNorthNorway)