Benedetta Galli, Dario Cappiello and Massimiliano Carassiti*
Department of Anaesthesia, Institution Campus Bio Medico, University School of Medicine, Rome, Italy
Received Date: July 23, 2014 Accepted Date: November 27, 2015 Published Date: November 30, 2015
Citation: Carassiti M,Cappiello D,Galli B (2015) One Shot Six Centres: A New Strategy in Ultrasound Guided Paravertebral Block. J Anesth Clin Res 6:580. doi: 10.4172/2155-6148.1000580
Copyright: © 2015 Galli B, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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The paravertebral block (PVB) is the technique of injecting local anaesthetic alongside the vertebral body close to where the spinal nerves emerge from the intervertebral foramen. This produces unilateral, segmental, somatic, and sympathetic nerve blockade in multiple contiguous thoracic dermatomes which is effective for managing acute and chronic pain. Recently PVB has also been used for surgical anaesthesia in patients undergoing several surgical procedures with improved postoperative outcomes. Unfortunately the spread of local anaesthetic and the anaesthetic effect is sometime unpredictable, even with a standardized ultrasound-guided technique. The aim of this study is to show a new approach for the Paravertebral block ultrasound-guided and confirmed by ENS using a single injection. This new approach allows an easy visualization and accurate puncture of the paravertebral space, ensuring good anaesthesia of reproducibility, productivity and effectiveness. In this study we obtained six dermatomes anaesthesia, with a single shot injection in all patients.
Paravertebral block; Ultrasound in regional anesthesia
Paravertebral blocks were initially described in the early twentieth century and their use was reintroduced in1979 by Eason and Wyatt [1,2]. Over the past 15 years paravertebral block has generated significant interest for the management of patients undergoing thoracic and abdominal surgical procedures. Several studies support the hypothesis that PVB are effective as epidural blocks for perioperative pain management without many of the side effects of neur-axial techniques [3-6]. Moreover the use of paravertebral block has been shown to delay the recurrence of tumours and the development of metastases in a retrospective analysis . The thoracic paravertebral space (TPVS) is a wedge-shaped space located on either side of the vertebral column. Anterolateral it is limited by the pleura (PP) while the superior costotransverse ligament (SCL), forms the posterior border. The base of the wedge is formed by the posterolateral surface of the vertebral body, intervertebral disk, and the intervertebral foramen. Interposed between the PP and the SCL there is a fibro elastic structure: the “endo thoracic fascia”. The TPVS communicates with the contiguous space above and below, the epidural space medially, the intercostal space laterally, the contralateral paravertebral space via the prevertebral and epidural route, and inferiorly with the retroperitoneal space posterior to the fascia transversalis. The most frequent indication for paravertebral blocks is perioperative management of pain for breast surgery [8-11] lithotripsy , minor abdominal surgery  and pelvic surgery , major abdominal surgery [15-17], VATS  and open thoracotomy [18-20]. Other than the data described , the author is not aware of any other published data describing different techniques to perform a real-time US pvb in the clinical setting. An ultrasound scan for PVB can be performed in the transverse (axial scan) or longitudinal (sagittal scan) axis with the patient in the sitting, lateral decubitus, or prone position. The prone position is useful in patients presenting for a chronic pain procedure when fluoroscopy may also be used in conjunction with ultrasound imaging. Currently, there are no data demonstrating an optimal axis for the scan or the intervention. It is often a matter of individual preference and experience. In our daily practice we have developed a new technique that allows us an optimal vision of the structures of the paravertebral region using an in-plane approach and rotating the probe gently until it is parallel to the coasts (Figure 1), as already described in a study on cadavers . Our aim was also to predict the distribution of the anaesthetic, a previously unsolved problem, using the technique of mixed US\ENS, to get a block that is as reproducible as possible.
After obtaining Institutional Ethical Committee approval and the patients' written informed consent, 34 patients aged between 50 and 80 years, ASA physical status ASA I- III who were scheduled to undergo thermo ablation for liver metastasis, quadrantectomy and open lung surgery were enrolled in the study. After application of routine monitoring and supplemental oxygen, all patients received midazolam 1 mg IV. A dose of 0.4 ml/kg of LA was prepared by of using 0.5% ropivacaine. Skin asepsis and sterile draping were performed, and the US probe was sheathed. All blocks were performed by one experienced anaesthesiologist. The probe (Esaote MyLab 25, transducer LA523E with frequency band 5-10 MHz) was placed at the spinous process, where it was possible to recognize the transverse process by the typical cone shadow. After localizing the pleura, the probe was rotated 30 degrees, parallel to the ribs. Then the lateral costo-transverse ligament was visualized above the pleura. A 21 Stimuplex needle (B. Braun Medical Milano S.P.A. Italy) was inserted and visualized in-plane. Once the lateral costo-transverse ligament was passed, the electroneuro-stimulator (stimuplex HNS12 B Braun) was turned on, and when muscle contractions were aroused at 0.5 mA, ropivacaine was injected. The correct diffusion of the local anaesthetic was visualized through ultrasounds when the typical detachment of the parietal pleura from the rib cage was obtained. The block extension was assessed by ice test and prick tests. The timing block (visualization and injection), success rate, onset time, dose of local anaesthetic, nausea and vomiting and any other complications were recorded. The timing block was defined as the time from the placement of the US probe on the patient (the time for skin preparation, draping, and probe sheathing was not included) to complete the anaesthetic injection around the nerve. Before discharge, the patients fill in a multiple choice questionnaire on the degree of satisfaction on a scale from 1-6(1 being “not satisfied” and 6 “Extremely satisfied”).
34 Pvt Blocks were registered. Patient demographics are summarized in Table 1. In all patients a correct visualization of the space and of the needle was obtained in less than 4 min (228 ± 132 sec). The median dose of local anaesthetic was (123 mg ± 21.1). The procedure was always well tolerated, with a complete anaesthesia 30 minutes after the injection in all cases (100%). Complete anaesthesia of six dermatomers was reached in 100% of patients. We have experienced an accidental bilateral block in one patient, without any consequences. No patient experienced nausea and vomiting. None of the patients complained about pain or discomfort and all were overall extremely satisfied. Complications associated to the paravertebral block were one vagal crisis during procedure (2.9%), and one episode of bilateral block (2.9%).
|Age (Mean ± yr)||Weight (kg)||Height (cm)|
|69 ± 9.3||70 ± 11.6||164.2 ± 7.7|
Table 1: Demographics data
In this investigation, our group has demonstrated objectively that the ultrasound visibility of the SCL, the paravertebral space, and the pleura is better when the ultrasound beam is oriented in a slightly oblique axis, i.e., with the ultrasound transducer tilted slightly laterally or outward . Although the spread of LA was reproducible , the anaesthetic effect was unpredictable, even with a standardized ultrasound-guided technique in volunteers. While it can be assumed that approximately four vertebral levels are covered by 20 ml LA, the somatic distribution of the pvt remains unpredictable . In a significant number of cases, the LA distributes into the epidural space, prevertebral, or to the contralateral side. That's why we use US/Ens guided technique to predict the distribution of the anaesthetic and the puncture behind the endo-thoracic fascia to get a longitudinal anaesthetic distribution [23,24]. We obtained reproducible anaesthesia in six dermatomers with a single injection in all patients. Previous studies showed that the most common difficulty performing ultrasound guided block is the visualization of the needle tip during its progress. For this reason, in our study we chose to direct the probe rotated to 30 degrees, aligning it with the ribs. Rotating the probe allows an easier visualization of the costo-transverse ligament and of the top of the paravertebral space, granting an optimal visual field for the in-plane approach with a latero-medial direction. Although the needle was always perfectly visualized with this approach, we stimulated a local response through the ENS technique. Electro-neuro-stimulation allows a more objective evaluation of the needle distance from the spinal nerves and, according with Naya, we may suppose that the voltage <0.5 mA indicates the needle is positioned ventral to the endothoracic fascia; so we are able to foresee the anaesthetic multi segmental longitudinal distribution pattern and, as a consequence, to reduce the rate of failure and dis homogeneous distribution. Finally, the 30 degrees echo graphic section provides a better acoustic window, granting a higher safety while approaching with the needle. Our study allowed us to obtain an adequate anaesthesia and analgesia in 100% of the patients, through a single paravertebral puncture. In conclusion, we successfully developed a technique for an Ens/ultrasound-guided puncture of the paravertebral space. This new approach allows an easy visualization and accurate puncture of the paravertebral space, ensuring good reproducibility, productivity and effectiveness, with rare and minor complications.
The authors declare that there is no conflict of interest.