Ondansetron versus ondansetron with dexamethasone to prevent intrathecal-morphine pruritus for caesarean patients: randomised double-blind trial

Commonly used antiemetics for prophylaxis of postoperative nausea and vomiting after Caesarean delivery with neuraxial morphine: a network meta-analysis

BACKGROUND

Dopamine antagonists, 5-HT3 antagonists, and dexamethasone are frequently used in obstetrics to prevent postoperative nausea and vomiting (PONV). However, the superiority of any drug class is yet to be established. This network meta-analysis aimed to compare the efficacy of these antiemetics for PONV prophylaxis in women receiving neuraxial morphine for Caesarean delivery.

METHODS

We searched PubMed, Embase, CENTRAL, Web of Science, and Wanfang Data for eligible randomised controlled trials. Primary outcomes were the incidences of postoperative nausea (PON) and postoperative vomiting (POV) within 24 h after surgery. We used a Bayesian random-effects model and calculated odds ratios with 95% credible intervals for dichotomous data. We performed sensitivity and subgroup analyses for primary outcomes.

RESULTS

A total of 33 studies with 4238 women were included. In the primary analyses of all women, 5-HT3 antagonists, dopamine antagonists, dexamethasone, and 5-HT3 antagonists plus dexamethasone significantly reduced PON and POV compared with placebo, and 5-HT3 antagonists plus dexamethasone were more effective than monotherapy. In the subgroup analyses, similar results were seen in women receiving epidural morphine or intrathecal morphine alone but not in women receiving intrathecal morphine with fentanyl or sufentanil. However, most included studies had some concerns or a high risk of bias, and the overall certainty of the evidence was low or very low.

CONCLUSIONS

Combined 5-HT3 antagonists plus dexamethasone are more effective than monotherapy in preventing PONV associated with neuraxial morphine after Caesarean delivery. Future studies are needed to determine the role of prophylactic antiemetics in women receiving intrathecal morphine and lipophilic opioids.

SYSTEMATIC REVIEW PROTOCOL

PROSPERO CRD42023454602.

Efficacy of intravenous dexamethasone on postoperative pain after caesarean delivery under spinal anaesthesia with an intrathecal long-acting opioid: a systematic review and meta-analysis

PURPOSE

Intravenous dexamethasone is recommended in elective caesarean delivery to decrease postoperative pain. However, the efficacy of spinal anaesthesia with an intrathecal long-acting opioid such as morphine or diamorphine for caesarean delivery has not been systematically investigated.

METHODS

We searched all randomized controlled trials (RCTs) of pregnant women undergoing caesarean delivery under spinal anaesthesia with an intrathecal morphine or diamorphine via MEDLINE, CENTRAL, EMBASE, ICTRP, and ClinicalTrials.gov on May 18, 2022. Primary outcomes were time to first rescue analgesia, consumption of oral morphine equivalents, and incidence of drug-related adverse reactions. We evaluated the risk of bias for each outcome using the Risk of Bias 2. We conducted a meta-analysis using a random effects model. We evaluated the certainty of evidence with the GRADE approach.

RESULTS

Five RCTs (455 patients) were included. The results of intravenous dexamethasone were as follows: time to first rescue analgesia (mean difference [MD] 0.99 h, 95% confidence interval [CI] - 0.86 to 2.84; very low certainty) and consumption of oral morphine equivalents (MD - 6.55 mg, 95% CI - 17.13 to 4.02; moderate certainty). No incidence of drug-related adverse reactions was reported (very low certainty).

CONCLUSION

The evidence was very uncertain about the efficacy of intravenous dexamethasone on time to first rescue analgesia and the incidence of drug-related adverse reactions. Intravenous dexamethasone probably reduces the consumption of oral morphine equivalents. Anaesthesiologists might want to consider intravenous dexamethasone for postoperative pain after caesarean delivery under spinal anaesthesia with an intrathecal long-acting opioid.