A comparative study of infusions of phenylephrine, ephedrine and phenylephrine plus ephedrine on maternal...

This randomized double blind study was started with an objective of management of spinal anaesthesia-induced hypotension in elective caesarean section by combining two commonly used vasopressors - ephedrine and phenylephrine in half of their usual doses with an expectation of reducing their foetomaternal side effects.

One hundred and thirty two patients were randomized into three groups to receive either 100 μg/ml phenylephrine (group-P, n=31) or 3 μg/ml ephedrine (group-E, n=33) or 50 mg phenylephrine plus 1.5 mg ephedrine/ml (group-PE, n=29). Immediately after spinal injection the study solution was started prophylactically in every patient at the rate of 40 ml/h. A predefined algorithm was used to adjust the infusion rate according to the systolic blood pressure (SBP).

Mean fall of SBP was significantly more in group-E than group-P (P=0.009) and group-PE (P=0.013). This was not significantly different when compared between group-P and group-PE (P=0.9). Episodes of hypotension and tachycardia were more in group-E than the other two groups. Statistically significant tachycardia was seen in Group-E than that in other two groups. Incidence of bradycardia and hypertension did not differ significantly among the groups. Maternal nausea and Apgar score were also comparable in three groups.

Current study claims that prophylactic phenylephrine 100 mg/ml is a better choice than ephedrine (3 mg/ml) or 50 mcg phenylephrine plus 1.5 mg ephedrine/ml in prevention of spinal anaesthesia-induced hypotension in elective caesarean section. Combination of two drugs in half the usual dose has no added advantage over phenylephrine, but this is better than ephedrine alone.