Clinical trial NCT01493986: Minimum Effective Volume of Ropivacaine 7.5 mg/ml for the Lateral and Sagittal Infraclavicular Brachial Plexus Block
Official 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.
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: PHASE4
Conditions: Pain
Keywords: Ropivacaine
Brachial plexus
Lead sponsor: University Hospital of North Norway
Sponsor class: OTHER
First posted: 2011-12-16
Enrollment: 25
Sex: ALL
Minimum age (years): 18
Maximum age (years): 65
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: NA
Intervention model: SINGLE_GROUP
Primary purpose: TREATMENT

Brief summary: 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.

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.

Eligibility criteria: 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

Primary outcomes:
measure: 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).
timeFrame: 30 minutes
Secondary outcomes:
Other outcomes:
Locations:
city: Tromsø
country: Norway
facility: University Hospital of North Norway
state: Troms
Study officials:
affiliation: University Hospital of North Norway
name: Lars M Ytrebo, Professor
role: PRINCIPAL_INVESTIGATOR
References: