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A randomised double-blind trial of phenylephrine and metaraminol infusions for prevention of hypotension during spinal and combined spinal-epidural anaesthesia for elective caesarean section.
Anaesthesia 2017; 72(5):609-617A

Abstract

Prophylactic vasopressor administration is commonly recommended to reduce maternal hypotension during spinal anaesthesia for caesarean section. Metaraminol has undergone limited investigation in obstetric anaesthesia for this purpose, particularly in comparison with phenylephrine. In this multicentre, randomised, double-blind, non-inferiority study, we compared prophylactic phenylephrine or metaraminol infusions, started immediately after spinal anaesthesia, in 185 women who underwent elective caesarean section. Phenylephrine was initially infused at 50 μg.min-1 , and metaraminol at 250 μg.min-1 . The primary outcome was the difference in umbilical arterial pH between groups; secondary outcomes included other neonatal acid-base measures, and maternal haemodynamic changes. The mean (SD) umbilical arterial pH was 7.28 (0.06) in the phenylephrine group vs. 7.31 (0.04) in the metaraminol group (p = 0.0002). The estimated mean (95%CI) pH difference of 0.03 (0.01-0.04) was above the pre-determined lower boundary of clinical non-inferiority, and also met the criterion for superiority. Umbilical artery lactate concentration was 2.8 (1.2) mmol.l-1 in the phenylephrine group vs. 2.3 (0.7) mmol.l-1 in the metaraminol group (p = 0.0018). Apgar scores did not significantly differ between groups. There was a higher incidence of hypotension, defined as systolic arterial pressure < 90% baseline, in the phenylephrine group; there was a higher incidence of hypertension and severe hypertension (systolic arterial pressure > 110% and > 120% baseline, respectively) in the metaraminol group. There was no significant difference between groups in the incidence of nausea, vomiting or maternal bradycardia. We conclude that, when used as an infusion to prevent hypotension after spinal anaesthesia for elective caesarean section, metaraminol is at least non-inferior to phenylephrine with respect to neonatal acid-base outcomes.

Authors+Show Affiliations

School of Medicine and Pharmacology, The University of Western Australia, Perth, Australia. School of Women's and Infants Health, The University of Western Australia, Perth, Australia.School of Medicine and Pharmacology, The University of Western Australia, Perth, Australia.St Michael's Hospital, Bristol, UK.Rockingham General Hospital, Rockingham, Australia.Biostatistics and Research Design Unit, Women and Infants Research Foundation, Perth, Australia.

Pub Type(s)

Journal Article
Randomized Controlled Trial

Language

eng

PubMed ID

28255987

Citation

McDonnell, N J., et al. "A Randomised Double-blind Trial of Phenylephrine and Metaraminol Infusions for Prevention of Hypotension During Spinal and Combined Spinal-epidural Anaesthesia for Elective Caesarean Section." Anaesthesia, vol. 72, no. 5, 2017, pp. 609-617.
McDonnell NJ, Paech MJ, Muchatuta NA, et al. A randomised double-blind trial of phenylephrine and metaraminol infusions for prevention of hypotension during spinal and combined spinal-epidural anaesthesia for elective caesarean section. Anaesthesia. 2017;72(5):609-617.
McDonnell, N. J., Paech, M. J., Muchatuta, N. A., Hillyard, S., & Nathan, E. A. (2017). A randomised double-blind trial of phenylephrine and metaraminol infusions for prevention of hypotension during spinal and combined spinal-epidural anaesthesia for elective caesarean section. Anaesthesia, 72(5), pp. 609-617. doi:10.1111/anae.13836.
McDonnell NJ, et al. A Randomised Double-blind Trial of Phenylephrine and Metaraminol Infusions for Prevention of Hypotension During Spinal and Combined Spinal-epidural Anaesthesia for Elective Caesarean Section. Anaesthesia. 2017;72(5):609-617. PubMed PMID: 28255987.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - A randomised double-blind trial of phenylephrine and metaraminol infusions for prevention of hypotension during spinal and combined spinal-epidural anaesthesia for elective caesarean section. AU - McDonnell,N J, AU - Paech,M J, AU - Muchatuta,N A, AU - Hillyard,S, AU - Nathan,E A, Y1 - 2017/03/03/ PY - 2017/01/19/accepted PY - 2017/3/4/pubmed PY - 2018/12/18/medline PY - 2017/3/4/entrez KW - cardiovascular effects KW - fetal blood gas values KW - neuraxial anaesthesia KW - spinal hypotension KW - treatment KW - uterine blood flow determinants SP - 609 EP - 617 JF - Anaesthesia JO - Anaesthesia VL - 72 IS - 5 N2 - Prophylactic vasopressor administration is commonly recommended to reduce maternal hypotension during spinal anaesthesia for caesarean section. Metaraminol has undergone limited investigation in obstetric anaesthesia for this purpose, particularly in comparison with phenylephrine. In this multicentre, randomised, double-blind, non-inferiority study, we compared prophylactic phenylephrine or metaraminol infusions, started immediately after spinal anaesthesia, in 185 women who underwent elective caesarean section. Phenylephrine was initially infused at 50 μg.min-1 , and metaraminol at 250 μg.min-1 . The primary outcome was the difference in umbilical arterial pH between groups; secondary outcomes included other neonatal acid-base measures, and maternal haemodynamic changes. The mean (SD) umbilical arterial pH was 7.28 (0.06) in the phenylephrine group vs. 7.31 (0.04) in the metaraminol group (p = 0.0002). The estimated mean (95%CI) pH difference of 0.03 (0.01-0.04) was above the pre-determined lower boundary of clinical non-inferiority, and also met the criterion for superiority. Umbilical artery lactate concentration was 2.8 (1.2) mmol.l-1 in the phenylephrine group vs. 2.3 (0.7) mmol.l-1 in the metaraminol group (p = 0.0018). Apgar scores did not significantly differ between groups. There was a higher incidence of hypotension, defined as systolic arterial pressure < 90% baseline, in the phenylephrine group; there was a higher incidence of hypertension and severe hypertension (systolic arterial pressure > 110% and > 120% baseline, respectively) in the metaraminol group. There was no significant difference between groups in the incidence of nausea, vomiting or maternal bradycardia. We conclude that, when used as an infusion to prevent hypotension after spinal anaesthesia for elective caesarean section, metaraminol is at least non-inferior to phenylephrine with respect to neonatal acid-base outcomes. SN - 1365-2044 UR - https://www.unboundmedicine.com/medline/citation/28255987/A_randomised_double_blind_trial_of_phenylephrine_and_metaraminol_infusions_for_prevention_of_hypotension_during_spinal_and_combined_spinal_epidural_anaesthesia_for_elective_caesarean_section_ L2 - https://doi.org/10.1111/anae.13836 DB - PRIME DP - Unbound Medicine ER -