Comparison of US-Guided Paravertebral and Proximal Intercostal Nerve Blocks

Study Overview
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Brief Summary
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The purpose of this study is to compare the proximal intercostal block to the more medial (classic) ultrasound-guided paravertebral block. The investigators hypothesize that the proximal intercostal block will allow for improved needle visualization, shorter block time, and improved safety profile compared to the classic paravertebral bock.

Detailed Description
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Although previous studies have made advances towards applying ultrasound guidance to the performance of paravertebral blocks (PVB), a technique combining both safety and technical ease remains elusive. The ideal technique (1) permits continuous visualization of the entire needle shaft and tip, (2) avoids aiming the needle tip and injectate directly toward the neuraxis or lung, and (3) is easy to perform. Visualization of all structures by ultrasound is essential to minimize the risk of vascular puncture, nerve root or spinal cord injury, and pneumothorax. Failure to consistently and quickly identify the transverse process and pleura, as occurs when using older techniques, results in several needle redirections, causing pain and discomfort to patients, and increases the potential risk of pneumothorax. The technical difficulty of applying previously-described US-guided techniques takes an inordinate amount of time and is clinically less practical within a busy surgical practice. In the current study, the investigators describe a novel, modified approach to real-time ultrasound-guided single shot paravertebral blockade, the proximal intercostal block (PICB), which utilizes a sagittal paramedian US probe placement to identify the intercostal space and PVS. In this method, instead of placing the probe at a fixed traditional distance of 2.5 cm from the spinous processes, the probe is moved laterally to obtain a comprehensive image, with a clear view of the ribs, internal intercostal membrane, and the parietal pleura. The investigators propose that moving the probe laterally towards the proximal intercostal space allows clearer simultaneous visualization of both pleura and needle as it advances towards the PVS, while achieving comparable injectate spread and, ultimately, similar or better clinical results. Such improved visualization will reduce the number of needle passes, increase confidence in the user, decrease block placement time, and improve overall block success. This technique combines the advantages of more lateral approaches (better visualization of structures, in particular the pleura) with the advantage of the more medial approaches (in-plane, closer, and not directed at the neuraxis).

Official Title
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A Prospective, Randomized Comparison Between the Ultrasound Guided Paravertebral Block and the Ultrasound Guided Proximal Intercostal Nerve Block

Conditions
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Pain

Intervention / Treatment
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* Procedure: Proximal Intercostal Block
* Procedure: Paravertebral Block


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Females age 18-85 years old ASA 1-3 Patient scheduled for unilateral or bilateral mastectomy with or without reconstruction Exclusion Criteria: Coagulopathy Patient refusal Allergy to local anesthetics

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 85 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Proximal Intercostal Block<br>See Intervention Section | Procedure: Proximal Intercostal Block<br>* After identifying the correct intercostal space, the ultrasound probe will be moved medially to identify the transverse processes, then again laterally from the transverse processes to rest over the ribs so as to obtain the best view of ribs and pleura. A 10cm, 21G needle will be inserted in-plane at the caudal border of the probe. An attempt will be made to keep the needle tip and the target injection position (just under the internal intercostal membrane (IIM)) in view. Correct needle tip placement will be demonstrated by depression of the pleura/endothoracic fascia upon local anesthetic injection and by lack of retrograde spread of LA over the muscles or the ribs. The LA will be injected in 4 cc aliquots after negative aspiration of air, CSF and blood.<br>* Other names: PICB;|
| Active Comparator: Paravertebral Block<br>See Intervention Section | Procedure: Paravertebral Block<br>* After identifying the correct intercostal space, the ultrasound probe will be placed between the adjacent transverse processes in a longitudinal/parasagittal plane measuring 2.5cm from the midline. The best possible view of the transverse processes, the superior costotransverse ligament and pleura will be obtained. An attempt will be made to keep the needle tip and the target injection position (immediately beneath the costotransverse ligament) in view. Correct placement of the needle tip will be demonstrated by depression of the pleura upon injection of local anesthetic and by lack of retrograde spread of LA over the muscles or transverse processes. The LA will be injected in 4 cc aliquots after confirming negative aspiration of air, CSF and blood.<br>* Other names: PVB;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Ultrasound Image Quality Score | The following will be assessed for each image and video, and saved during each block performed: Best possible image of block anatomy (including the pleura, transverse process/rib, costotransverse ligament/internal intercostal membrane, as appropriate) as well as needle location. Video of the space during injection, reflecting the injectate spread. The images will be rated by a separate regional anesthesiologist not involved in study, but proficient with both types of blocks and ultrasound imaging. The following score 3 point scale will be used to rate visibility: 0=not visible, 1=hardly visible, 2=well visible, 3=very well visible. Maximum score possible=18 including both pieces of media. | Evaluated at time of block | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Block Performance Time | Defined as the sum of imaging and needling times | Evaluated at time of block | 
| Imaging Time | Defined as the time interval between contact of the ultrasound probe with the patient, and the acquisition of a satisfactory image (which will be saved and analyzed later by a regional anesthesiologist blinded to the particular aims of the study). | Established during block performance | 
| Needling Time | Defined as the time interval between the start of the skin wheal and the end of local anesthetic injection through the block needle. | Established during block performance | 
| Number of Needle Passes | Initial needle insertion will be counted as first pass. Any subsequent needle advancement, preceded by a retraction of more than 2 cm, will be counted as an additional pass. | Established during block performance | 
| Distance of Injection Sites from Midline | Measured and recorded (one of our clinical aims) | Established during block performance | 
| Presence of Perioperative Block-Related Complications | The presence of the following complications will be recorded: Horner's syndrome Pneumothorax Local anesthetic systemic toxicity (LAST) Pain on injection Evidence of contralateral block (for unilateral procedures) | Within 24 hours of block placement | 
| Effectiveness of the Block | Patients will be asked to provide a verbal rating score of pain (0-10) at two time points: one hour following extubation, and 24h following block placement. At the 1 hour following extubation time point, we will be checking the coverage of the block in terms of dermatomal spread (see below). | One hour following extubation, and at 24 hours following block placement | 
| Dermatomal spread | Number of dermatomal block levels, determined by loss of sensation to cold (ice) or to loss of pinprick sensation in the PACU one hour after extubation. | One hour following extubation | 
| Opioid requirement | Opioid requirement, including intraoperative, PACU, and during the entire hospital admission, normalized to morphine equivalents. | Evaluated at 1 hour after extubation, and then at 24 hours following the block | 
| Prolonged postoperative pain | Postoperative contact via secure e-mail at will assess for the incidence of chronic pain. | 6 and 12 months after surgery | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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NERVE BLOCK, ANESTHESIA RECOVERY PERIOD, PAIN MANAGEMENT