• Etheridge John-Paul B JB Anesthesia, Kelowna General Hospital, Kelowna, British Columbia, Canada., Frederick De Villiers, Jan Venter, Pam Squire, Brenda Farnquist, and Roderick J Finlayson.
• Anesthesia, Kelowna General Hospital, Kelowna, British Columbia, Canada.
• Reg Anesth Pain Med. 2020 Mar 1; 45 (3): 176-179.

BackgroundAlthough the value of ultrasound-guided (USG) lumbar medial branch blocks (MBB) has previously been examined in several clinical trials, blocking the L5 dorsal ramus (DR) remains a technical challenge and we sought to examine the accuracy of a novel technique targeting this level.MethodsIn this prospective cohort study, 115 patients scheduled for an L4 MBB and L5 DR block underwent an ultrasound scan to assess their lower spine sonoanatomy. Subjects in whom the necessary landmarks could be visualized underwent a USG L5 DR block using a pivot technique, which involved redirecting a needle from its position on the L5 transverse process after an L4 MBB. Success was determined by a blinded observer who examined the contrast distribution on postprocedural X-ray images. In addition to the final needle position, performance time, the number of needle passes, and any complication were recorded.ResultsA total of 100 patients had a USG block and 15 patients (13%) were excluded because of poor landmark visibility. The latter group presented a significantly higher body mass index (38.90±7.50 vs 26.31±4.25 kg/m2, p=0.004). A total of five failures were noted (95% success rate), this included three patients with transitional anatomy in whom needles were placed at the wrong level and two cases of incomplete contrast coverage possibly related to the partial intravascular injection. Performance time was 153.93±41.56 s and the median number of needle passes was 2 (range 4). No significant complications were noted.ConclusionThe pivot technique provides a reliable approach for USG L5 DR ramus blocks.Trial Registration NumberNCT03805906.© American Society of Regional Anesthesia & Pain Medicine 2020. No commercial re-use. See rights and permissions. Published by BMJ.

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