ITM + Bupivacaine QLB vs. ITM + Sham Saline QLB for Cesarean Delivery Pain

The purpose of this trial is to determine the efficacy of a postoperative analgesia strategy that incorporates quadratus lumborum block (QLB) in conjunction with a multi-modal post-cesarean analgesia strategy. The investigators hypothesize that QLB will provide superior post-cesarean analgesia compared to the current standard of care, multi-modal analgesia. Thus, analgesia following cesarean section using QLB compared to the current standard of care alone will be further investigated. Current practice for cesarean surgical intervention consists of multi-modal analgesia (i.e., Intrathecal morphine (ITM) and scheduled post-operative non-opioid oral analgesics, with oral opioid analgesics reserved for breakthrough pain). Investigators will measure side-effects associated with each strategy: Standard of care methods consisting of intrathecal morphine (ITM) plus scheduled non-opioid analgesics in conjunction with prn opioid analgesics for breakthrough pain will be utilized for both. The experimental treatment arm will entail standard of care in addition to QLB. The sham comparator will entail standard of care in addition to QLB with saline. For each strategy, we will measure and model associated economic ramifications; such factors will include drug costs, procedure costs, and costs associated with length of stay and re-admissions. The quadratus lumborum block (QLB) is similar to the transversus abdominis plane (TAP) block, but differs slightly in regards to the anatomical region where local anesthetic is injected. Since the quadratus lumborum (QL) is more posteriorly located, it theoretically confers greater safety due to enhanced visualization. The TAP block has been studied extensively for post-cesarean delivery pain, consistently showing that it is not superior to ITM for post-operative analgesia; however, it may prove to be helpful in patients with breakthrough pain despite the use of ITM, or in patients who were unable to receive ITM (e.g. general anesthesia for cesarean, contraindications to neuraxial morphine). Thus, ITM is superior to TAP alone for post-cesarean analgesia, but it is associated with a dose-dependent increased risk for opioid related side effects. In 2015, Blanco et. al. published a study specifically using the QLB for postoperative pain after cesarean delivery. In this study, they compared a true QLB to a sham QLB all in patients who did not receive ITM, and found that the QLB provided improved pain control and decreased the need for post-operative opioids. Another study in 2016 demonstrated that the QLB is superior to the TAP block in regards to decreasing post-operative pain following c-section. Unfortunately, neither study compared the QLB to ITM (part of the current gold standard for post-cesarean delivery pain, multimodal analgesia). The gap in knowledge regarding the utility of QLB as part of a multimodal analgesic approach including ITM for cesarean section warrants further investigation. Clinicians are constantly searching for methods to provide patients with the most effective medical interventions that provide maximal benefit and minimal harm. Post-operative pain control following cesarean delivery is an area that is important to patients and to providers, and the introduction of the QLB for this purpose has the potential to improve analgesic benefit.