Key result
Phenylephrine resulted in a higher umbilical artery pH and lower base excess compared to ephedrine for treating hypotension during caesarean section.
Why the study?
The standard choice of vasopressor between ephedrine and phenylephrine for maternal hypotension following subarachnoid block remains controversial, particularly regarding effects on the foetus.
Does phenylephrine improve fetal acid-base status compared to ephedrine when used to treat hypotension after subarachnoid block for caesarean section?
RCT (n=100)
Quasi-randomized (odd/even numbers)
No
Does phenylephrine improve fetal acid-base status compared to ephedrine when used to treat hypotension after subarachnoid block for caesarean section?
Phenylephrine results in better fetal acid-base status compared to ephedrine when used to treat maternal hypotension during spinal anesthesia for caesarean section, though both are equally effective for blood pressure control.
Answers are grounded in this paper and cite their sources.
Supports phenylephrine over ephedrine for caesarean hypotension; confirms superior fetal acid-base status in RCT evidence.
BACKGROUND Subarachnoid block has been widely used for caesarean sections and is found to be safe. Hypotension being the most common complication may adversely affect both the mother and foetus. Different measures used to treat this hypotension include preloading with crystalloids/colloids and treatment with vasopressors. The standard choice of vasopressor agents such as ephedrine and phenylephrine is still a controversial issue. It is therefore important to compare the efficacy of the two drugs in the prevention and treatment of maternal hypotension after subarachnoid block and particularly assess their effect on the foetus. The purpose of this study was to assess and compare the foetal acid-base status and APGAR score following administration of bolus dose of ephedrine or phenylephrine that was given intravenously for maintenance of arterial blood pressure during lower segment caesarean section (LSCS) under a subarachnoid block. METHODS 100 parturients (18 to 35 years) scheduled for elective caesarean section under subarachnoid block were selected and divided into two groups of 50 each. Group P received 50 mcg i.v bolus of phenylephrine and Group E received 6 mg of ephedrine IV bolus whenever the blood pressure dropped 20 % from baseline or systolic blood pressure ˂ 90 mmHg. Haemodynamic parameters were measured in all patients. APGAR scores at 1 and 5 minutes following delivery of baby were assessed and cord blood was obtained for acid-base status analysis immediately following delivery. RESULTS Hemodynamic parameters including heart rate, systolic blood pressure, diastolic blood pressure, and mean arterial pressure did not show any significant difference between the two groups, however, Group E showed higher heart rates. The difference in umbilical artery pH (P-value < 0.001) and base excess (P-value = 0.004) was statistically significant with Group E showing lower pH and higher base excess values than Group P. There was no statistically significant difference in neonatal APGAR scores between the two groups. CONCLUSIONS Phenylephrine and ephedrine are equally efficient in managing hypotension during subarachnoid block for caesarean delivery. Thus, either vasopressor can be used although phenylephrine may be a better choice. KEY WORDS Caesarean Section, Phenylephrine, Ephedrine.
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Muneer et al. (2021) conducted an RCT in Hypotension during subarachnoid block for caesarean section (n=100). Phenylephrine vs. Ephedrine 6 mg IV bolus was evaluated on Umbilical artery pH (p=<0.001). Phenylephrine resulted in a higher umbilical artery pH and lower base excess compared to ephedrine for treating hypotension during caesarean section.
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