Thoracic Intervertebral Foramen Block

Study Overview
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Brief Summary
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The investigators hypothesize an alternative way to perform thoracic paravertebral block, by placing the needle tip over and behind the transverse process of vertebra, via the thoracic intervertebral foramen. This anesthetic procedure is called thoracic intervertebral foramen block. The study aims to verify the spread of dye on to the the nervous structures of retropleural space (the ventral rami, the communicating rami, and the sympathetic trunk), and into the thoracic paravertebral space and epidural space. To accomplish this, a prospective cadaveric study was designed.

Detailed Description
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This is a prospective cadaveric study. The anesthetic procedure is performed on 2 corpses for which autopsy is requested, in accordance with Italian Low. Before performing the autopsy, the corps is placed in the left and then in the right lateral position, to perform bilateral block. The anesthetic procedure is performed at second (T2), fifth (T5), ninth (T9), and twelfth (T12) thoracic vertebra. The ultrasonography is performed by using a high-frequency linear-array US transducer. A Tuohy needle is inserted in-plane to the ultrasound beam in a lateral-to-medial direction gently to contact the spinous process, into the skeletal muscle plane of the erector spinae muscle. Then, the needle tip is moved to reach the angle between the transverse process and spinous process. Subsequently, the needle tip is gently inserted and advanced for 2 mm along with the superior limit of the vertebral pedicle, until losing contact with the bone. Five ml methylene blue 1% dye (MB) were subsequently injected. The anesthetic procedure is bilaterally performed. Two continuous catheter sets are used and threaded 1 cm from the needle tip, for a bilateral continuous block. The catheters are inserted from the caudal to the cephalic direction. At the end of the anesthetic procedure, a second look ultrasound scan of thoracic paravertebral space was performed. Subsequently, the corps is put in supine position, and autopsy is started.

Official Title
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Thoracic Intervertebral Foramen Block: a Prospective Cadaveric Study

Conditions
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Anesthesia; Functional, Anesthesia, Local, Spinal Cord

Intervention / Treatment
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* Procedure: Thoracic intervertebral foramen block


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: corps for which autopsy is required Exclusion Criteria: corps under Legal custody of Italian Low
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: Other
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Thoracic intervertebral foramen block<br>The thoracic intervertebral foramen block is performed at second (T2), fifth (T5), ninth (T9), and twelfth (T12) thoracic vertebra. The ultrasonography is performed by using a high-frequency linear-array ultrasound transducer. A Tuohy needle is inserted in-plane to the ultrasound beam in a lateral-to-medial direction gently to contact the spinous process, into the skeletal muscle plane of the erector spinae muscle. Then, the needle tip is moved to reach the angle between the transverse process and spinous process. Subsequently, the needle tip is gently inserted and advanced for 2 mm along with the superior limit of the vertebral pedicle, until losing contact with the bone. Five ml methylene blue 1% dye (MB) are subsequently injected. The anesthetic procedure is bilaterally performed. Two continuous catheter sets were used and threaded 1 cm from the needle tip, for a bilateral continuous block. The catheters are inserted from the caudal to the cephalic direction. | Procedure: Thoracic intervertebral foramen block<br>* The thoracic intervertebral foramen block is performed by placing the needle tip over and behind the transverse process of vertebra, via the thoracic intervertebral foramen.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Retropleural spread | Assess mL of dye on to the nervous structures of retropleural space (the ventral rami, the communicating rami, and the sympathetic trunk) | During autopsy | 
| Thoracic paravertebral spread | Assess mL of dye on to the thoracic paravertebral space | During autopsy | 
| Epidural spread | Assess mL of dye on the epidural space | During autopsy | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Iatrogenic damages | Number of punctures of vertebral blood vessels, spinal nerve roots, and pleura | During autopsy | 
| Distance (mm) between the catheter tip and the thoracic intervertebral foramen content is also evaluated | Distance (mm) between the catheter tip and the thoracic intervertebral foramen content is evaluated | During autopsy | 
| Second look ultrasound scan | Area (square cm) of anechoic shadow on the paravertebral space | After the anesthetic procedure |