Department of Anesthesia and Intensive Care Medicine, University Hospital Copenhagen, Roskilde, DenmarkDepartment of Anesthesia and Intensive Care Medicine, Aarhus University Hospital, Aarhus, DenmarkDepartment of Anesthesia and Intensive Care Medicine, University Hospital Copenhagen, Roskilde, Denmark, email@example.com
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To the EditorWe address 3 issues in the case report by Chakraborty et al.,1 namely, the appropriate reference to the original quadratus lumborum plane block2 and the so-called Shamrock sign,3,4 the definition of the relevant endpoint of injection, and the best and safest approach to this endpoint.Blanco’s original2 ultrasound-guided “no pop” technique was presented as an abstract in 2007. However, the abstract did not describe how to inject local anesthetics or the endpoint of injection. Blanco5 later elaborated on these details. Sauter et al.3,4 coined the term Shamrock sign and used it to indicate a new technique to block the lumbar plexus. However, it was Børglum et al.6 who used the Shamrock sign to indicate a new transmuscular quadratus lumborum block technique published as an e-letter in the British Journal of Anaesthesia in 2013 (Fig. 1).The relevant endpoint of injection for the transmuscular quadratus lumborum block is into the interfascial plane between the quadratus lumborum and the psoas major muscles as shown by Chakraborty et al.1 This endpoint seems to ensure the spread of the injectate to the thoracic paravertebral space, as originally described by Børglum et al.6 in the aforementioned letter based on their personal observations from magnetic resonance imaging studies.A needle approach through the quadratus lumborum muscle with the patient placed in the lateral position is also used by Visoiu and Yakovleva7 in their description of their continuous technique. It is our personal observation that the transmuscular approach avoids the risk of unintentional penetration of the peritoneal cavity contrary to the technique described by Chakraborty et al.1 that seems to be carrying the risk of penetrating the peritoneal recess between the abdominal wall muscles and the psoas major (Fig. 1). EChristian Kruse Hansen, MDMette Dam, MDDepartment of Anesthesia and Intensive Care MedicineUniversity Hospital CopenhagenRoskilde, DenmarkThomas Fichtner Bendtsen, MD, PhDDepartment of Anesthesia and Intensive Care MedicineAarhus University HospitalAarhus, DenmarkJens Børglum, MD, PhDDepartment of Anesthesia and Intensive Care MedicineUniversity Hospital CopenhagenRoskilde, Denmarkjens.borglum@gmail.