Discussion
nausea, skin pruritus, pain, hypotension, depression
CHRONIC PAIN, RESPIRATORY DEPRESSION, SIDE EFFECTS, SEVERE PRE-ECLAMPSIA
Cesarean delivery is often performed in high-risked pregnancies to reduce the morbidity and mortality rate of high-risk mothers and newborns. However, the procedure is invasive and is often associated with severe postoperative incisional pain, which can have an impact on maternal endocrinology and postoperative recovery. Intrathecal morphine provides prolonged postoperative analgesia and reduces the amount of postoperative intravenous analgesics, and also significantly reduces the incidence of chronic pain and postpartum depression after cesarean delivery. Intrathecal morphine has a capping effect, and its safe dose is 50-200ug. Side effects are dose-related, specifically respiratory depression, hypotension, nausea and vomiting, skin pruritus, and so on[This prospective randomized trial was designed to compare the use of TAP block in conjunction with intrathecal morphine versus intrathecal morphine alone in women with severe pre-eclampsia. The results showed that combined use of intrathecal morphine and TAP block could reduce VAS pain scores at 4,8 and 12 h after surgery at rest. This finding was contradicted by those of Costelloet al[The incidence of side effects was not statistically different in both groups which may be due to the not enough sample size or related to our study protocol. Our saline-based sham block may create a placebo effect for women, resulting in no difference in the incidence of side effects.Most patients rated their satisfaction with pain control as good and the total incidence of satisfaction in the TAP group was higher than that in the Sham group, which suggested an additional analgesic effect may have been gleaned from the TAP block. The use of TAP block did not result in a reduction in opioid consumption from the PCA device in the first 12 h and this finding was different from the previous research[The TAP block is a local anesthetic injected into the neurofascial layer between the internal oblique and transversus abdominis muscles to block the anterior abdominal wall T6-L1 segmental nerve, which provides good analgesia for abdominal wall incision, reduces pain scores and opioid dosage and is beneficial for rapid postoperative recovery, and is an important component of multimodal analgesia[The benefit of TAP block for postoperative analgesia is evident in patients undergoing cesarean section without intrathecal morphine. It reduces opioid consumption in PCA devices and is safe with few side effects.In patients who had taken intrathecal morphine, Kendall et al[There are some limitations to our study. Firstly, we take the VAS pain score of the patients as the primary outcome which mainly is due to the different tolerance and sensitivity to the pain of each patient. Secondly,There is potential to use a higher concentration with a volume increased to the maximum safe dose. Further studies using different approaches for TAP or increasing concentrations of local anaesthetics with adjuncts to prolong analgesic duration are warranted.Thirdly,this study is a single-center study with a small sample size, and there are region and race limitations. Although these limitations, our study perform an actual TAP block with saline rather than a simulated sham injection can increase the internal validity of the investigation. In the future, we will expand the sample size and include multi-center to explore more multimodal analgesia to seek the best postoperative analgesia.