EP132 Posterocranial spread after pericapsular nerve group block, a pathway to failure?

<h3></h3> <b>Please confirm that an ethics committee approval has been applied for or granted:</b> Not relevant <h3>Background and Aims</h3> A pericapsular nerve group (PENG) block can be used to reduce pain after hip surgery as part of a multimodal postoperative pain management. This approach targets the sensory branches of the anterior portion of the hip capsule originating from the lumbar plexus (L2-L4). More research is needed to fully understand the characteristics of this block. Since this approach is a field block, its efficacy is volume-dependent. In this study, we compared the spread of different volumes of dye using a PENG block approach in two body donors. <h3>Methods</h3> Two male unembalmed human bodies were obtained from the human body donation program of the university (with written informed consent). The four hip regions were injected respectively with 5 ml, 10 ml, 15 ml or 20 ml of a custom-made mixture (10% latex, 1.5% methylene blue 10 mg/ml and 88.5% water) by an experienced anaesthesiologist under ultrasound guidance. The spread of the injectates was measured and compared using dissection of the hip regions. <h3>Results</h3> Injections with 5 and 10 ml of dye did not result in staining of the targeted nerves. With 15 and 20 ml of dye, we observed a posterocranial spread without staining the targeted femoral, obturator or accessory obturator nerves. The dye was located on top of the ilium. <h3>Conclusions</h3> To our knowledge, this is the first time a spread over the ilium has been described. This atypical posterocranial spread might explain clinical failure of PENG blocks in some patients, suggesting a steep learning curve to apply this relatively new block effectively.