Quadratus Lumborum in Cesarean Section Trial (QUALICS)

C-section is one of the most performed surgical procedures in the world, and presents great potential for postoperative pain, especially in the first 48 hours. Pain in this period represents a risk for evolution to chronic pain, but its incidence is still very divergent when comparing the studies, ranging from 1% to 18%.

The use of intrathecal morphine (MIT) is consecrated as a first-choice method of analgesia for post-partum cesarean delivery; however, its use carries relevant side effects for the puerpera, such as pruritus, nausea, urinary retention and , more rarely, respiratory depression. In the last decade, new adjunctive forms of postoperative analgesia have become more popular, such as regional blockades, highlighting the blockage of the Transversus Abdominis plane block (TAP) and the Quadratus Lumborum block (QL), taking as benefits the prolonged analgesia they provide and the low incidence of side effects. Another factor that contributes to the popularization of regional blocks is the increasing availability of ultrasound devices in the anesthetic-surgical environment. Studies evaluating TAP block after cesarean section performed under spinal anesthesia have shown a discrete benefit in decreasing postoperative opioid consumption in addition to improving pain scores. When comparing MIT with TAP block, the superiority of MIT is due to visceral analgesia while TAP block is restricted to abdominal wall analgesia.

Ultrasound-guided Lumbar Quadrant blockade has gained prominence due to its analgesic superiority over the TAP block, because in addition to providing somatic analgesia it also seems to inhibit visceral pain since the local anesthetic reaches the paravertebral space, this was observed by magnetic resonance imaging with contrast injected at the site of the QL block.

Reviewing the literature in 2018, there are no clinical trials comparing the use of intrathecal morphine with the quadratus lumborum block.