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Frequent epidural spread can be prevented when performing an ultrasound guided approach to the paravertebral space.
- Jacques E. Chelly, MD, PhD, MBA, Andrea Fanelli, MD (16 June 2009)
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Ultrasound for paravertebral block
- Sean Q M Tighe (7 May 2009)
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Jacques E. Chelly, MD, PhD, MBA, Professor of Anesthesiology (with Tenure) and Orthopedic Surgery, Vice Chair of Clinical Research University of Pittsburgh Medical Center Department of Anesthesiology, Andrea Fanelli, MD
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To the Editor We read with interest the Luyet et al’ article describing an ultrasound-guided approach to the paravertebral space.1 Based on anatomical dissections, the authors proposed a latero-medial approach with a site of introduction of the needle 2.5 – 4 cm away from the spinous process. Since the proposed landmarks very much resemble the landmarks used for a paramedial approach to the epidural space, it is not surprising that they also reported 30% epidural spray and even epidural placement of catheters. In fact Purcell-Jones et al’ using the same approach reported 70% of epidural spread.2 The technique described by these authors contrasts with our daily approach to the paravertebral block.3 From December of 2003 to March 2009, we have performed 24,808 single and continuous paravertebral blocks using a site of introduction of the needle 2.5 cm away from the spinous process (at the level of the transverse process) with the needle kept strictly parallel to the spinous process with an injection of no more than 5 ml of local anesthetic through the needle. With this technique, we have found epidural spread to be an exception. The same approach can be applied using ultrasound guidance. Accordingly, an ultrasound probe (2 – 5 MHz curved array transducer) connected to a S-Nerve (Sonosite, Bothell, WA) is positioned 2.5 cm parallel to the spinous process View Image . With this approach, it is also possible to easily identify the transverse processes (T) as well as the costo-transverse ligament (CTL) and the pleura View Image.View Image. Once the anatomical landmarks have been clearly identified, a 22 gauge (single paravertebral) or 18 gauge Tuohy needle (continuous paravertebral catheter) can be introduced toward the costo-transverse ligament. After the needle is positioned in the paravertebral space (between the costo- transverse ligament and the pleura) 5 ml of the local anesthetic solution is slowly injected. This produces an anterior displacement of the pleura. In conclusion, we believe that the approach proposed by Luyet et al’ should not be considered, because of the associated high risk of epidural spread and epidural placement of the catheter. We would like to suggest that our described approach be used instead to minimize the risks of epidural spray and epidural placement of the catheter. Andrea Fanelli, MD Regional Anesthesia Fellow University of Pittsburgh Medical Center Shadyside Hospital Jacques E. Chelly, MD, PhD, MBA Professor of Anesthesiology (with Tenure) and Orthopedic Surgery Vice Chair of Clinical Research Director of the Regional and Orthopedic Fellowships Director of the Division of Acute Interventional Perioperative Pain and Regional Anesthesia Department of Anesthesiology University of Pittsburgh Medical Center Director of Orthopedic Anesthesia, UPMC Shadyside Hospital Director of Acute Interventional Perioperative Pain UPMC Presbyterian-Shadyside Hospital Telephone: (412) 623-4135 Fax: (412) 623-4188 Email: chelje@anes.upmc.edu References 1. Ultrasound-guided paravertebral puncture and placement of catheters in human cadavers: an imaging study. Luyet C, Eichenberger U, Greif R, Vogt A, Szücs Farkas Z, Moriggl B. Br J Anaesth. 2009; 102:534-9. 2. Purcell-Jones G, Pitcher CE, Justins DM. Paravertebral somatic nerve blocks: a clinical radiographic, and computed tomographic study in chronic pain patients. Anesth Analg 1989; 68:32-9. 3. Chelly JE, Uskova A, Merman R, Elliott MN, Ben-David B, Matusic B. Factors influencing the paravertebral depth: A multifactorial approach to the paravertebral depth. Br. J Anaesth. 2008; 101:250-4. Conflict of Interest:None declared |
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Sean Q M Tighe, Consultant Anaesthetist Countess of Chester Hospital Foundation NHS Trust
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I applaud Luyet et al for a most illuminating cadaver study on the use of ultrasound guidance for paravertebral block (PVB) with an oblique, in-plane,cranio-caudal approach and a curvilinear transducer (1). However, there are other approaches that might be safer. A linear transducer can be used at a frequency of 7-8 MHZ in the cranio- caudal direction, with slight lateral angulation. There are then two choices; ultrasound assisted or ultrasound guided PVB. In ultrasound assisted PVB, the transverse process (TP) is marked and the depth measured to guide subsequent conventional needle insertion in the axial plane, without ultrasound. The depth of the pleura is also measured to limit needle insertion (2). This is a particularly useful technique in large or obese adults, in whom it is often difficult to locate the TP blindly. View Image In ultrasound guided PVB, an 18G epidural needle is introduced just lateral to the laterally tilted probe, perpendicular to the skin surface, in an "out-of-plane" axial approach. The tip can be guided onto the TP and then caudally or cranially into the paravertebral space (PVS). Local anaesthetic injection demonstrates pleural deflection anteriorly. A catheter can be passed and seen in the space. The PVS spread can be scanned cranially and caudally to decide if additional levels should be blocked. Although the oblique approach recommended by Luyet et al is innovative, the medial angulation of the needle risks penetration of the neuraxis and the frequent epidural extension they noted. The "out of plane" approach described above minimises this complication. However, I am unconvinced of the practical use of ultrasound guided PVB in adults, as the views are often poor, particularly in the deeper lower thoracic and lumbar regions. Ultrasound guided block also takes considerably more time than the conventional approach, with a similar success rate and incidence of complications, in my experience. Nevertheless, it is very useful for confirming correct catheter placement on the rare occasions this is indicated. A lateral in-plane approach can also be used, placing the probe medio- laterally. The pleural reflection is clearly seen, as well as the shadow of the TP. However, the needle tip is lost from view as it passes under the TP and this is a concern, so close to the neuraxis. (http://uk.youtube.com/watch?v=L7hVLNjBiSA&feature=related) Luyet et al passed their catheters 5 cms into the PVS. Other authors recommend 1-3 cms, in order to minimise epidural extension (3). This might explain the high rate of catheter tip misplacement reported. References 1. Luyet C, Eichenberger U, Greif R, Vogt A, Szücs Farkas Z, Moriggl B. Ultrasound-guided paravertebral puncture and placement of catheters in human cadavers: an imaging study. Br J Anaesth 2009; 102: 534-9. 2. Pusch F, Wildling E, Klimscha W, Weinstabl C. Sonographic measurement of needle insertion depth in paravertebral blocks in women. Br J Anaesth 2000; 85: 841-3 3. Karmakar MK. Thoracic paravertebral block. Anesthesiology 2001; 95: 771 -80. S.Q.M. Tighe Chester, UK E-mail: sean.tighe@coch.nhs.uk Conflict of Interest:None declared |
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