Quadratus lumborum block can be used for the hip surgery and abdominal surgery postoperative analgesia. But the lower thoracic to the hip dermatomes can't be blocked at the same time. The anesthetists used the same method, but had produced the different dermatomes were blocked. The investigators hypothesized that this was due to local anesthetics was injected to different locations of the anterior thoracolumbar fascia. If the investigators inject local anesthetics to the anterior thoracolumbar extrafascial (between the anterior layer of thoracolumbar fascia and psoas major muscle), this produced the dermatomal coverage from lower abdominal to hip. In this case, the investigators speculated the local anesthetic spread to the lumbar paravertebral space via the fascia and the fascicle of psoas major. A different situation was when the investigators injected local anesthetics to anterior thoracolumbar subfascial (between the anterior layer of thoracolumbar fascia and quadratus lumborum), the lower thoracic dermatomes were blocked. The investigators speculate that the local anesthetic injected subfascial could spread cephalad to lower thoracic paravertebral space posterior to the endothoracic fascia via lateral arcuate ligament.~The investigators confirm the hypothesis in the pilot trial. therefore, the investigators need to trial with large sample. The investigators plan to improve the clinical guidance of quadratus lumborum block technology, so that more patients benefit.
Quadratus lumborum block can be used for the hip surgery and abdominal surgery postoperative analgesia. But the lower thoracic to the hip dermatome can't be blocked at the same time. The anesthetists used the same method, but had produced the different dermatome were blocked. The investigators hypothesized that this was due to local anesthetics was injected to different locations of the anterior thoracolumbar fascia. If the investigators inject local anesthetics to the anterior layer of thoracolumbar extrafascial, this produced the dermatomal coverage from lower abdominal to hip. A different situation was when the investigators injected local anesthetics to anterior thoracolumbar subfascia, the lower thoracic dermatome were blocked.