Ephedrine and phenylephrine for the treatment of maternal hypotension in a chronic sheep model of increased placental vascular resistance

Tiina Erkinaro, T. Kavasmaa, M. Päkkilä, G. Acharya, K. Mäkikallio, S. Alahuhta, J. Räsänen

Research output: Contribution to journalArticle

34 Scopus citations

Abstract

Background. We hypothesized that ephedrine and phenylephrine are equal with respect to uterine and placental haemodynamics and fetal acid-base status after exposure to maternal hypoxaemia and hypotension in a chronic sheep model of increased placental vascular resistance (RUA). Methods. At 114-135 days gestation, chronically inst rumented fetal sheep underwent placental embolization leading to increased RUA. Twenty-four hours after embolization, the ewes were anaesthetized and randomized to receive boluses of ephedrine (n=7) or phenylephrine (n=6) for epidural-induced hypotension after maternal hypoxaemia. Uterine (QUtA) and placental (QUA) volume blood flows and uterine vascular resistance (RUtA) and RUA were recorded. Uterine (PIUtA) and umbilical artery (PIUA) pulsatility indices were obtained by Doppler ultrasonography. Fetal arterial blood samples were analysed for acid-base values and lactate concentrations. Results. During hypotension, QUtA, fetal pH, BE, and Po2 decreased whereas RUtA, PIUtA, RUA, and fetal lactate concentration increased. With ephedrine, QUtA, RUtA, PIUtA, RUA, and fetal P o2 returned to baseline. Fetal pH, BE, and lactate concentration did not change from hypotensive values. With phenylephrine, QUtA remained lower (P=0.007) and RUtA (P=0.007), PIUtA (P=0.013), and RUA (P=0.050) higher than at baseline. Fetal Po2 returned to baseline and fetal pH and BE did not change from hypotensive values. However, fetal lactate concentration increased further (mean difference 1.49, 95% confidence interval 0.72-2.26 mmol litre-1; P=0.004). Conclusions. In a chronic sheep model of increased placental vascular resistance, compared with ephedrine administration, phenylephrine administration was associated with impaired uterine and placental haemodynamics and increased fetal lactate concentrations.

Original languageEnglish (US)
Pages (from-to)231-237
Number of pages7
JournalBritish journal of anaesthesia
Volume96
Issue number2
DOIs
StatePublished - Feb 2006

Keywords

  • Anaesthesia, obstetric
  • Anaesthetic techniques, epidural
  • Sympathetic nervous system, pharmacology, ephedrine
  • Sympathetic nervous system, pharmacology, phenylephrine

ASJC Scopus subject areas

  • Anesthesiology and Pain Medicine

Fingerprint Dive into the research topics of 'Ephedrine and phenylephrine for the treatment of maternal hypotension in a chronic sheep model of increased placental vascular resistance'. Together they form a unique fingerprint.

  • Cite this