Preventive intramuscular phenylephrine in elective cesarean section under spinal anesthesia: A randomized controlled...

Area of Science:

• Anesthesiology
• Obstetrics
• Pharmacology

Background:

• Phenylephrine is a first-line vasoactive drug for cesarean sections under spinal anesthesia.
• Intravenous phenylephrine use has a high rate of hypotension.
• Limited research exists on the effects of prolonged intramuscular phenylephrine use.

Purpose of the Study:

• To investigate the effects of preventive intramuscular phenylephrine on fetal and maternal outcomes during elective cesarean delivery.
• To compare intramuscular phenylephrine with intravenous phenylephrine and placebo.

Main Methods:

• 99 healthy parturients were randomized into three groups: intramuscular phenylephrine (5 mg), intravenous phenylephrine (100 μg), or placebo.
• Umbilical artery pH was the primary outcome.
• Rescue medications were used as needed for blood pressure and heart rate management.

Main Results:

• The intramuscular phenylephrine group showed significantly higher umbilical artery pH (7.32) compared to the intravenous (7.25) and placebo (7.21) groups.
• Fetal acidosis rates were lower in the intramuscular group (3%) versus intravenous (15%) and placebo (30%).
• Maternal intraoperative hypotension was significantly reduced in the intramuscular group (12%) compared to intravenous (39%) and placebo (73%).

Conclusions:

• Preventive intramuscular phenylephrine resulted in better neonatal acid-base status compared to intravenous administration or placebo.
• Intramuscular phenylephrine provided more stable maternal hemodynamics during elective cesarean under spinal anesthesia.
• Intramuscular phenylephrine is a potentially superior alternative for managing hypotension in this setting.