Remifentanil in obstetric analgesia: a dose-finding study

Area of Science:

• Anesthesiology
• Obstetrics
• Pharmacology

Background:

• Intravenous patient-controlled analgesia (PCA) with remifentanil represents a novel approach to systemic opioid pain management during labor.
• Establishing the minimum effective dose is crucial for optimizing its use in obstetric care.

Purpose of the Study:

• To determine the minimum effective dose of intravenous remifentanil administered via patient-controlled analgesia (PCA) for labor pain relief.
• To assess the efficacy and safety profile of remifentanil PCA during the first stage of labor.

Main Methods:

• Twenty healthy parturients undergoing the first stage of labor participated.
• Remifentanil hydrochloride was administered intravenously via PCA, with a starting bolus dose of 0.2 microg/kg and 0.2 microg/kg increments every 60 minutes.
• The PCA bolus was initiated by the parturient at the onset of uterine contractions, with a 1-minute lockout interval.

Main Results:

• All 17 patients who completed the study achieved adequate pain relief.
• The median effective PCA bolus dose was 0.4 microg/kg, with a median consumption of 0.066 microg x kg(-1) x min(-1).
• Significant individual variations in effective dose (0.2-0.8 microg/kg) and consumption were observed, alongside frequent maternal oxygen desaturation, sedation, and reduced fetal heart rate variability.

Conclusions:

• Remifentanil PCA demonstrates effectiveness in providing labor analgesia, with a median effective dose identified.
• Wide individual variations in required dosage and the frequent occurrence of potentially serious side effects may restrict its application in obstetric settings.