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Summary Phenylephrine is recommended for the management of hypotension after spinal anaesthesia in women undergoing caesarean section. Noradrenaline, an adrenergic agonist with weak β‐adrenergic activity, has been reported to have a more favourable haemodynamic profile than phenylephrine. However, there are concerns that noradrenaline may be associated with a higher risk of fetal acidosis, defined as an umbilical artery pH < 7.20. We performed a systematic review of trials comparing noradrenaline with phenylephrine, concentrating on primary outcomes of fetal acidosis and maternal hypotension. We identified 13 randomised controlled trials including 2002 patients. Heterogeneity among the studies was high, and there were too few data to calculate a pooled effect estimate. Fetal acidosis was assessed in four studies that had a low risk of bias and a low risk of confounding, that is, studies which used a prophylactic vasopressor and where women received the allocated vasopressor only. There were no significant differences between these studies. No significant differences were observed for hypotension. Two trials found a significantly lower incidence of bradycardia when using noradrenaline. Cardiac output was significantly higher after noradrenaline in two of three studies. For other secondary outcomes including nausea, vomiting and Apgar scores at 1 and 5 min, no studies found significant differences. The evidence so far is too limited to support an advantage of noradrenaline over phenylephrine. Concerns of a deleterious effect of noradrenaline on fetal blood gas status cannot currently be assuaged by the available data from randomised controlled studies.

There are data suggesting that intravenous dexamethasone has an effect on postoperative analgesia when given during single-shot spinal anaesthesia. However, the research literature is equivocal. We performed a systematic literature search followed by conventional meta-analysis (random effects model). We used trial sequential analysis to control for type-1 and -2 statistical errors. We also performed a leave-one-out metaanalysis for our primary outcome, the consumption of intravenous morphine in the first 24 postoperative hours. We applied the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system to rate the level of evidence. We obtained data from 1133 patients, reported in 17 trials. Reporting quality was high, with low risk of bias. Dexamethasone use was associated with a significant reduction in 24-h morphine consumption, the mean difference (95%CI) being À4.01 (À5.01 to À3.01) mg, 6 trials, 326 participants, I 2 = 0%. Trial sequential analysis showed that there was firm evidence for the primary outcome, and leave-one-out metaanalysis showed that our result was not driven by one single trial. The GRADE evaluation showed a high level of evidence, suggesting that further studies are unlikely to alter the result. The time to first analgesic request (95% CI) was significantly prolonged by 86.62 (10.62-162.62) min, I 2 = 93%, in the dexamethasone group. For other secondary outcomes including number of patients requiring rescue analgesia, or visual analogue scale pain scores, we found no evidence of a significant difference between the treatment arms. We report a high level of evidence that intravenous dexamethasone improves postoperative analgesia after spinal anaesthesia.

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