ESP Volunteer LA Spread Controlled by MRI

Background and Objectives: The Thoracic Erector Spinae Plane Blockade (ESPB) is a regional anesthesia technique recently described by Forero M in November 2016 , whereby local anesthetic (LA) is injected in the inter Fascial space between posteriorly the fascia of Erector Spinae Muscles (IFS-ESP) (the iliocostalis, longissimus, and spinalis muscles ) and anteriorly the inter-transverse ligament to achieve multi-metameric analgesia for thoracic or upper abdominal surgery. Recent studies published showed controversies on the spread of the local anesthetic and also the clinical efficiency . The clarification of mechanism of the paravertebral block is one example for the effectiveness of Magnetic Resonance imaging (MRI) in this context We therefore designed a prospective study in volunteers to examine the spread of LA via MRI investigation in correlation with the extent of somatic block after a standardized ultrasound (US) guided ESPB. Our study will study the spread at T4 or T5 level which is the level used for most of thoracic, cardiac and breast surgeries to determine if dye would spread anteriorly to the involve or igins of the ventral and dorsal branches of the spinal nerves. Methods: After ethical committee approval we will select 10 Healthy volunteers to perform Unilateral ESP single shot block with a very low dose of Local anesthetic (LA) (Ropivacaine 0.5% 1 mg/kg (Maximal dose recommended = 3 mg/kg ) mixed with 0,1ml gadolinium After injection an ultrasound image of the spread of the LA with an easy 3 Dimension will be acquired. 10 and 30 minutes after injection a MRI will be performed to analyze the ultrasound spread. An Evaluation of the extension of Sensory Blockade. Patient will be kept under monitoring for 1,5 hours to assess any complication Sensory block will be assessed. At 1 week after the study day, all volunteers will undergo an investigation of the puncture sites to exclude puncture- related infection or hematoma. Statistical analysis will be