Flow dynamics of ultrasound-guided lumbar plexus block in adults

Background and Aims: The outcomes of plexus and peripheral nerve blocks depend on needle-nerve contact and the spread of local anesthetic (LA) around the plexus or nerve. Needle-nerve distance and spread of LA could be visualized during US-guided lumbar plexus block (LPB). Material and Methods: After Institutional Ethics Committee approval and after obtaining informed consent, 24 American Society of Anesthesiologists'-physical status I-III patients who underwent surgical fixation of fractures of proximal femur were enrolled. Spinal anesthesia was a primary anesthetic in all patients. At the end of the surgery, all patients received US and neurostimulation-aided LPB at the third lumbar nerve root (LNr). The primary aim was to determine the spread of LA in the lumbar plexus area with the relation of the needle tip and LNr contact. The secondary aim was to understand block efficacy in terms of pain scores monitored at regular intervals and 100 mg intravenous tramadol was administered as a rescue analgesic if VAS >4. Results: In all 24 patients, we observed an oval and antegrade LA spread after lumbar plexus was identified with neurostimulation at L3. With the needle closer to intervertebral foramina (IVF), a retrograde spread was visualized. Only 2/24 patients received rescue analgesia in the first 24 h. Conclusion: The type of spread after the US-guided LPB could predict block success of block and a possible epidural spread.