Key result
Phenylephrine and mephentermine were comparable in preventing the overall incidence of hypotension during spinal anesthesia for cesarean section (40% vs 45%), but phenylephrine resulted in significantly fewer hypotensive episodes (13 vs 32).
Why the study?
Hypotension is a common side effect when neuraxial analgesia is administered to the obstetric population, prompting evaluation of the efficacy of mephentermine versus phenylephrine for its management following spinal anesthesia in cesarean section.
Does prophylactic phenylephrine compared to mephentermine improve the management of hypotension in females undergoing elective cesarean section under spinal anesthesia?
RCT (n=40)
Single-blind
Sealed envelope technique
No
Does prophylactic phenylephrine compared to mephentermine improve the management of hypotension in females undergoing elective cesarean section under spinal anesthesia?
Absolute Event Rate: 40% vs 45%
p-value: p=not significant
Both phenylephrine and mephentermine effectively prevent hypotension during spinal anesthesia for cesarean section, but phenylephrine offers better blood pressure maintenance despite higher rates of reactive hypertension and bradycardia.
May favor phenylephrine to limit hypotensive episodes in cesarean spinal anesthesia; leaves open practice change pending higher-level evidence.
Hypotension is a common side effect when neuraxial analgesia is administered to the obstetric population. To find out the efficacy of mephentermine and phenylephrine for management of hypotension following spinal anesthesia in cesarean section. The study has been undertaken at the Department of Anesthesiology of ESI- PGIMSR, Manicktala, Kolkata, after obtaining approval from Institute Ethical Committee. Uni-centric randomized, single blind, prospective & comparative study. Unpaired Student’s t-test, chi-square test, Fisher’s exact test. The 40-female scheduled for elective caesarean section were randomly divided into two groups of 20 each. Subarachnoid block was performed with 2.2mL of 0.5% hyperbaric bupivacaine. Prophylactic infusion of vasopressor started at a rate of 60 ml/h 0f 50 mcg/min for phenylephrine (group P, n=20) and 600 mcg/min for mephentermine (Group M, n=20) Hemodynamic parameters were monitored. At the end of surgery and the patients were transferred to the postoperative care unit (PACU). Considering absolute values of hypotension, both groups are comparable in terms of preventing hypotension; however, phenylephrine had better control of maintenance over blood pressure than that of mephentermine. Reactive hypertension is common in phenylephrine infusion. Bradycardia is more prevalent in phenylephrine infusion than that of mephentermine while tachycardia is more common in mephentermine. Side effects like dyspnea, nausea/vomiting, headache is more common during hypotensive episodes. None of the drugs causes any untoward effect on fetus.
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Panıgrahı et al. (2020) conducted an RCT in Hypotension during spinal anesthesia (n=40). Phenylephrine vs. Mephentermine 600 mcg/min infusion was evaluated on Incidence of hypotension (p=not significant). Phenylephrine and mephentermine were comparable in preventing the overall incidence of hypotension during spinal anesthesia for cesarean section (40% vs 45%), but phenylephrine resulted in significantly fewer hypotensive episodes (13 vs 32).
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