Dispersion of Local Anesthetic on the Erector Spinae Plane Block in Cadavers

Study Overview
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Brief Summary
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This study aims to better understand the dispersion of local anesthetic on the Erector Spinae Block, a new technique developed for analgesia. It consists on injection of local anesthetic around the posterior muscles of the Spine. In this study, the investigators will make the injection with coloring solution on cadavers and by dissection will note the dispersion of the solution according to injectate volume. The investigators hypothesize more volume allows bigger spread and will allow new indications of this technique in perioperative analgesia and treatment of chronic Pain

Detailed Description
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The study's methodology will include performing ultrasound guided erector spinae block in cadavers included in the study according to eligibility criteria. After signing of written consent form, the participants will be randomized on the height of the block (vertebral level - T3, T12 and L4) and the volume to be injected (10, 20 and 30ml). The block will be performed by experienced physicians on the technique by ultrasound guidance and fixed pressure measured with an in-line pressure monitor (15 psi) with the cadaver in the lateral position. The cadavers will be submitted to autopsy by standard thoracoabdominal midline incision, with the viscera removed for analysis. The cadavers will have their paraspinal muscles removed (quadratus lumborum and psoas major), the medial parietal pleura opened and the number of levels with colored solution registered, noting the spread to ventral rami of spinal nerves and to the paravertebral space.

Official Title
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Determination of Relationship Between Volume and Dispersion of Local Anesthetic on Ultrasound-guided Erector Spinae Plane Block in Cadavers

Conditions
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Nerve Block

Intervention / Treatment
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* Procedure: Erector Spinae Plane Block


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Fresh Cadavers (not subject to formaldehyde fixation process or frozen > 24h) Age > 18 years Written informed consent signed by responsible party Height > 150cm and < 190cm Exclusion Criteria: Previous spinal surgery Severe spinal deformity BMI > 35 kg/m2 Absence of a responsible party to sign the written informed consent

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: The cadavers will be randomized to receive the intervention (Erector Spinae Plane Block) on different levels (Vertebral level - T3, T12 and L4) and different volumes (10, 20 and 30ml)
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: T3 10ml<br>The cadaver will receive an ultrasound-guided Erector Spinae Plane Block with 10ml of coloring solution at the T3 vertebral level | Procedure: Erector Spinae Plane Block<br>* Ultrasound guided injection of coloring solution (methylene blue diluted in water) with a 18G echogenic tuohy needle deep to the plane of the erector spinae muscles.<br>|
| Experimental: T3 20ml<br>The cadaver will receive an ultrasound-guided Erector Spinae Plane Block with 20ml of coloring solution at the T3 vertebral level | Procedure: Erector Spinae Plane Block<br>* Ultrasound guided injection of coloring solution (methylene blue diluted in water) with a 18G echogenic tuohy needle deep to the plane of the erector spinae muscles.<br>|
| Experimental: T3 30ml<br>The cadaver will receive an ultrasound-guided Erector Spinae Plane Block with 30ml of coloring solution at the T3 vertebral level | Procedure: Erector Spinae Plane Block<br>* Ultrasound guided injection of coloring solution (methylene blue diluted in water) with a 18G echogenic tuohy needle deep to the plane of the erector spinae muscles.<br>|
| Experimental: T12 10ml<br>The cadaver will receive an ultrasound-guided Erector Spinae Plane Block with 10ml of coloring solution at the T12 vertebral level | Procedure: Erector Spinae Plane Block<br>* Ultrasound guided injection of coloring solution (methylene blue diluted in water) with a 18G echogenic tuohy needle deep to the plane of the erector spinae muscles.<br>|
| Experimental: T12 20ml<br>The cadaver will receive an ultrasound-guided Erector Spinae Plane Block with 20ml of coloring solution at the T12 vertebral level | Procedure: Erector Spinae Plane Block<br>* Ultrasound guided injection of coloring solution (methylene blue diluted in water) with a 18G echogenic tuohy needle deep to the plane of the erector spinae muscles.<br>|
| Experimental: T12 30ml<br>The cadaver will receive an ultrasound-guided Erector Spinae Plane Block with 30ml of coloring solution at the T12 vertebral level | Procedure: Erector Spinae Plane Block<br>* Ultrasound guided injection of coloring solution (methylene blue diluted in water) with a 18G echogenic tuohy needle deep to the plane of the erector spinae muscles.<br>|
| Experimental: L4 10ml<br>The cadaver will receive an ultrasound-guided Erector Spinae Plane Block with 10ml of coloring solution at the L4 vertebral level | Procedure: Erector Spinae Plane Block<br>* Ultrasound guided injection of coloring solution (methylene blue diluted in water) with a 18G echogenic tuohy needle deep to the plane of the erector spinae muscles.<br>|
| Experimental: L4 20ml<br>The cadaver will receive an ultrasound-guided Erector Spinae Plane Block with 20ml of coloring solution at the L4 vertebral level | Procedure: Erector Spinae Plane Block<br>* Ultrasound guided injection of coloring solution (methylene blue diluted in water) with a 18G echogenic tuohy needle deep to the plane of the erector spinae muscles.<br>|
| Experimental: L4 30ml<br>The cadaver will receive an ultrasound-guided Erector Spinae Plane Block with 30ml of coloring solution at the L4 vertebral level | Procedure: Erector Spinae Plane Block<br>* Ultrasound guided injection of coloring solution (methylene blue diluted in water) with a 18G echogenic tuohy needle deep to the plane of the erector spinae muscles.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Spread of Coloring Solution secondary to volume injected and vertebral level of injection | Observation of coloring solution around the spinal nerves as they exit the vertebral foramen. Comparison of number of spinal nerves colored according to the volume injected and injection site. | 3 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Spread of coloring solution to paravertebral space | Observation of coloring solution on the paravertebral space. Comparison of number of levels of the paravertebral space colored according to volume injected and injection site. | 3 hours |