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.

Inclusion Criteria:

- Elective cesarean planned under spinal anesthesia

- Singleton pregnancy

- American Society of Anesthesiologists (ASA) classification score of 2 (or less)

- Gestational age of at least 37 weeks

- Intention to breastfeed infant

Exclusion Criteria:

- Contraindications to neuraxial blockade (such as clinically relevant coagulopathy,
recent anticoagulant use, patient refusal, or localized skin infection overlying the
site of needle entry)

- Anatomical abnormalities contraindicating spinal or QLB placement

- Received/Conversion to general anesthesia

- Received supplemental parenteral anesthesia (sedation) for any reason (e.g.
unanticipated prolonged surgical procedure)

- History of chronic pain

- History of chronic opioid use/abuse

- History of Subutex, methadone, other maintenance therapy