Metaraminol trumps ephedrine for elective caesarean
Metaraminol may be a better vasopressor than ephedrine for mothers undergoing elective caesarean section, a recent meta-analysis has found.
Accessing the databases of PubMed, Embase and the Cochrane Library, researchers retrieved four randomized controlled trials that compared metaraminol with other vasopressors for spinal anaesthesia during caesarean delivery. The cumulative sample included 409 participants.
Relative to ephedrine, metaraminol resulted in a higher mean umbilical arterial pH (standardized mean difference [SMD], 0.82, 95 percent CI, 0.01–1.62; p=0.05) and a lower incidence of arterial pH <7.2 (risk ratio [RR], 0.08, 0.01–0.63; p=0.02). Nauseous vomiting was also significantly lower in those treated with metaraminol (RR, 0.16, 0.04–0.57; p=0.005).
In contrast, both vasopressors yielded comparable incidence rates of Apgar scores <7 at 1 minute (RR, 0.62, 0.08–4.85; p=0.65), hypotension (RR, 0.56, 0.26–1.17; p=0.12) and hypertension (RR, 1.44, 0.82–2.54; p=0.20).
When compared with phenylephrine, metaraminol resulted in a higher mean umbilical arterial pH (SMD, 0.42, 0.15–0.68; p=0.002) and incidence rate of hypertension (RR, 1.80, 1.32–2.46; p=0.0002).
No differences were observed for the incidence rate of umbilical pH <7.2 (RR, 0.18, 0.02–1.48; p=0.11), Apgar scores <7 at 1 minute (RR, 0.40, 0.11–1.45; p=0.16), hypotension (RR, 0.80, 0.53–1.22; p=0.30), or nausea or vomiting (RR, 0.53, 0.16–1.73; p=0.29).
Overall, prophylactic metaraminol appears to be superior to ephedrine for elective caesarean section delivery, while being at least not inferior to phenylephrine, said researchers. There is a need for further studies to facilitate the selection of the optimal vasopressor.