It is vital to apply adequate postoperative analgesia following Caesarean section (C-section), since it will affect the distinct surgical recovery requirements of the parturient. The ultrasound-guided quadratus lumborum block (QLB), first introduced by Blanco R. in 2007, has been recognized as an effective abdominal wall block approach, in which local anesthetic injected from the posterior abdomen will spread around the quadratus lumborum muscle and block the intermuscular nerves. In addition, such block is also closely related to multiple sympathetic fibres and is connected to the thoracic paravertebral space. Typically, QLB is found to be effective, which can provide satisfactory analgesic effect.~Midazolam is one of the clinically water-soluble benzodiazepines and effective to produce the analgesic effect through the neuraxial pathways. The organs and joints of humans have the benzodiazepine receptor, and midazolam is revealed to produce the analgesic effect through the gamma-aminobutyric acid receptors (GABA) in the spinal cord. Previous studies have reported that the midazolam (75 μg/kg) through the intraarticular route can decrease the pain intensity for arthroscopic knee surgery. In addition, the intrathecal midazolam (2 mg) is reported to prolong the duration of analgesia without any adverse effects following knee arthroscopies. Perineural midazolam has been also evaluated in brachial plexus block.
Midazolam has been used in regional anesthesia of brachial plexus block; it has offered accepted postoperative pain relief. This study will use it in as an adjuvant to bupivacaine 0.25% in quadratus lumborum block in caesarean section