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Solution to the challenging part of the Shamrock method during lumbar plexus block

2014; Elsevier BV; Volume: 113; Issue: 3 Linguagem: Inglês

10.1093/bja/aeu277

1471-6771

Jui‐An Lin, Hong Lu,

Spinal Hematomas and Complications

Editor'The ‘Shamrock method' is considered to be the standard approach for lumbar plexus block.1Lin JA Lu HT Chen TL Ultrasound standard for lumbar plexus block.Br J Anaesth. 2014; 113: 188-189Abstract Full Text Full Text PDF PubMed Scopus (11) Google Scholar As Sauter and colleagues2Sauter AR Ullensvang K Bendtsen TF Borglum J The ‘Shamrock Method' a new and promising technique for ultrasound-guided lumbar plexus block.Br J Anaesth. 2013; (e-letter)(http://www.bja.oxfordjournals.org/forum/topic/brjana_el%3B9814)Crossref Google Scholar have described, the most challenging part of the Shamrock method is to start with a correct puncture angle to approach the plexus. Although we can puncture the skin according to the landmark-guided method (4 cm lateral to the midline in adults)3Lumbar plexus block.in: Hadzic A Hadzic's Peripheral Nerve Blocks and Anatomy for Ultrasound-Guided Regional Anesthesia. McGraw-Hill, New York2012: 217-228Google Scholar with an absolute posterior–anterior needle direction, the plexus might be located higher or lower than expected. Therefore, there might be a need to redirect the needle either laterally or medially after skin puncture in order to approach the plexus. The more deviated the angle from the original, the lesser the possibility that the ultrasound beam will be reflected back to the transducer receiver; hence, the image would be poorer. In our opinion, the best way to avoid needle angling after skin puncture is to find a more accurate needle entry point to keep the needle trajectory (from skin puncture point to the plexus) almost always perpendicular to the ultrasound beam during Shamrock lumbar plexus block. Our solution to the challenge is fine tuning the needle entry point instead of 4 cm lateral to the midline. Without changing the original posterior–anterior needle direction, the skin is punctured at the level targeting the centre of the postero-medial quadrant of psoas major muscle, where the plexus is expected to be encountered.2Sauter AR Ullensvang K Bendtsen TF Borglum J The ‘Shamrock Method' a new and promising technique for ultrasound-guided lumbar plexus block.Br J Anaesth. 2013; (e-letter)(http://www.bja.oxfordjournals.org/forum/topic/brjana_el%3B9814)Crossref Google Scholar The distance from the bottom of the transducer to the plexus obtained in the ultrasound image (Fig. 1a) could be applied to help minimize the chance of needle redirection. This needle entry point (Fig. 1b) is suggested to create the shortest distance from the skin to the plexus and at the same time optimize the needle shaft visibility for the Shamrock method. Compared with other lumbar paravertebral structures, the ultrasound visibility for psoas major muscle is also reported to be highest in average-weight adults,4Karmakar MK Li JW Kwok WH Soh E Hadzic A Sonoanatomy relevant for lumbar plexus block in volunteers correlated with cross-sectional anatomic and magnetic resonance images.Reg Anesth Pain Med. 2013; 38: 391-397Crossref PubMed Scopus (33) Google Scholar thus making it a reasonable target in clinical practice. This solution provides spatial information regarding how far away from the transducer we should insert the needle (Fig. 1b) and clearly addresses the most challenging part during Shamrock lumbar plexus block. None declared.