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

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.

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Key information

Conditions

Pain Neurologic Manifestations Pathological Conditions, Signs and Symptoms Signs and Symptoms

Age range

18 year–65 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 4

Primary location

University Hospital of North Norway

Tromsø, Troms, 9038, Norway

About this study

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 If such a response is obtained, the needle is withdrawn (in steps of 1 mm), until the motor response disappears.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.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Ropivacaine

Drug

Dosage. Onset time

Other names: Naropin

Primary outcomes

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).

Time frame: 30 minutes

Sponsors and collaborators

Lead sponsor

University Hospital of North Norway

Other

Registry information

Official study title

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.

Important dates

Study start: 2012
Primary completion: 2012
Study completion: 2012
First posted: Dec 16, 2011
Registry last updated: Sep 11, 2012

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Published trials that share one or more normalized conditions with this study.

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