Comparison of the treatment effects of methoxamine and combining methoxamine with atropine infusion to maintain blood pressure during spinal anesthesia for cesarean delivery: a double blind randomized trial

X.-J. Luo, M. Zheng, G. Tian, H.-Y. Zhong, X.-J. Zou, D.-L. Jian

Department of Anesthesiology, Renmin Hospital, Hubei University of Medicine, Shiyan, Hubei, China. rhjdl@ctgu.edu.cn

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• Pharmacology

OBJECTIVE: Hypotension is a common complication of spinal anesthesia for cesarean delivery. Atropine is a vagus nerve blocker that can antagonize vagus excitation to mitigate the reflex bradycardia. We aimed to assess the effect of methoxamine-atropine therapy in treating spinal anesthesia hypotension for cesarean section.

PATIENTS AND METHODS: This is a double-blind randomized controlled study. Women under spinal anesthesia for elective caesarean delivery received boluses of methoxamine 2 mg alone (Group M, n = 40), or with addition of atropine 0.1 mg (Group MA1, n = 40), atropine 0.2 mg (Group MA2, n = 40) or atropine 0.3 mg (Group MA3, n = 40) upon a maternal systolic pressure ≤ 80% of baseline. The primary endpoint was systolic blood pressure and the secondary endpoints were maternal heart rates, instant neonatal heart rates, umbilical artery pH and umbilical artery base excess.

RESULTS: Changes in systolic blood pressure were similar among the four groups. The incidences of bradycardia in groups M and MA1 were significantly higher than those in group MA2 and MA3. The fetal heart rates after delivery in groups MA2 and MA3 were higher than those in group M and MA1 but within the normal range. The acid-base status had no difference in the four groups.

CONCLUSIONS: Methoxamine-atropine combination has a similar efficacy to methoxamine alone but has an increased hemodynamic stability and a less adverse effect occurrence.

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