TY - JOUR
T1 - Effects of ephedrine and phenylephrine on uterine and placental circulations and fetal outcome following fetal hypoxaemia and epidural-induced hypotension in a sheep model
AU - Erkinaro, Tiina
AU - Mäkikallio, K.
AU - Kavasmaa, T.
AU - Alahuhta, S.
AU - Räsänen, J.
N1 - Funding Information:
This study was supported by grants provided by the Academy of Finland and the University of Oulu. The authors wish to thank Pasi Ohtonen, MSc, for statistical consultation.
PY - 2004/12
Y1 - 2004/12
N2 - Background. Recent studies support the use of α-agonists during regional anaesthesia in uncomplicated term pregnancies. We hypothesized that ephedrine and phenylephrine, administered for maternal hypotension following fetal hypoxaemia, are equal in respect of fetal outcome. Methods. At 117-132 days gestation, chronically instrumented, anaesthetized and mechanically ventilated ewes were randomized to receive boluses of ephedrine (n=9) or phenylephrine (n=8) for maternal epidural-induced hypotension after a period of fetal hypoxaemia. Uterine (QUtA) and placental (QUA) volume blood flows were measured with perivascular transit-time ultrasonic flow probes, and uterine (RUtA) and placental (RUA) vascular resistances were computed from volume blood flows and maternal and fetal mean arterial pressures. Uterine (PlUtA) and umbilical artery (PlUA) pulsatility indices were obtained by Doppler ultrasonography. Results. Ephedrine increased QUtA and decreased RUtA and PlUtA from a hypotensive to baseline level and had no significant effect on umbilical circulation. With phenylephrine, QUtA remained lower (P=0.011) and RUtA higher (P=0.043) than at baseline, although PlUtA decreased to baseline level. PlUA increased from baseline with phenylephrine (P=0.007), whereas QUA decreased (P=0.050). Maternal volume expansion with hydroxyethyl starch decreased RUtA significantly irrespective of the vasopressor used. There were no significant differences in fetal blood gas values or lactate concentrations between the ephedrine and phenylephrine groups. Conclusions. Despite the more favourable effects on uterine and placental circulations of ephedrine over phenylephrine, no significant differences in fetal acid-base status or lactate concentrations were observed.
AB - Background. Recent studies support the use of α-agonists during regional anaesthesia in uncomplicated term pregnancies. We hypothesized that ephedrine and phenylephrine, administered for maternal hypotension following fetal hypoxaemia, are equal in respect of fetal outcome. Methods. At 117-132 days gestation, chronically instrumented, anaesthetized and mechanically ventilated ewes were randomized to receive boluses of ephedrine (n=9) or phenylephrine (n=8) for maternal epidural-induced hypotension after a period of fetal hypoxaemia. Uterine (QUtA) and placental (QUA) volume blood flows were measured with perivascular transit-time ultrasonic flow probes, and uterine (RUtA) and placental (RUA) vascular resistances were computed from volume blood flows and maternal and fetal mean arterial pressures. Uterine (PlUtA) and umbilical artery (PlUA) pulsatility indices were obtained by Doppler ultrasonography. Results. Ephedrine increased QUtA and decreased RUtA and PlUtA from a hypotensive to baseline level and had no significant effect on umbilical circulation. With phenylephrine, QUtA remained lower (P=0.011) and RUtA higher (P=0.043) than at baseline, although PlUtA decreased to baseline level. PlUA increased from baseline with phenylephrine (P=0.007), whereas QUA decreased (P=0.050). Maternal volume expansion with hydroxyethyl starch decreased RUtA significantly irrespective of the vasopressor used. There were no significant differences in fetal blood gas values or lactate concentrations between the ephedrine and phenylephrine groups. Conclusions. Despite the more favourable effects on uterine and placental circulations of ephedrine over phenylephrine, no significant differences in fetal acid-base status or lactate concentrations were observed.
KW - Anaesthesia, obstetric
KW - Anaesthetic techniques, epidural
KW - Sympathetic nervous system, pharmacology, ephedrine
KW - Sympathetic nervous system, pharmacology, phenylephrine
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U2 - 10.1093/bja/aeh273
DO - 10.1093/bja/aeh273
M3 - Article
C2 - 15465843
AN - SCOPUS:9744242681
SN - 0007-0912
VL - 93
SP - 825
EP - 832
JO - British journal of anaesthesia
JF - British journal of anaesthesia
IS - 6
ER -