Remifentanil at a Relatively Elevated Dose in Active Phase is Safe and More Suitable Than Fixed Lower Dose for Intravenous Labor Analgesia.

Background: Intravenous labor analgesia is recommended as an alternative for parturients who have contraindications to epidural analgesia. There are several opioid analgesics and different administering regimens used in the clinic. This study aimed to compare the effectiveness and safety of two intravenous remifentanil dosage regimens in the first labor stage. Patients and Methods: One hundred and fifteen parturients with a contraindication to epidural analgesia but were willing to receive systemic labor analgesia were randomized into group A received a fixed dose of remifentanil throughout the first stage of labor, and group B received an elevated dose of remifentanil during the active phase of the first stage both by patient-controlled analgesia (PCA). Maternal numerical rating scale (NRS) pain score and oxygen desaturation, sedation efficacy, satisfaction, as well as maternal and fetal adverse reactions were recorded and compared. Results: The mean NRS pain scores before analgesia and in the latent phase showed no statistically significant difference between the two groups (P > 0.05). However, during the active phase, group B demonstrated significantly lower mean NRS pain scores and lowest pain score compared to group A (P < 0.05). Furthermore, group B exhibited higher overall sedation scores and satisfaction scores in comparison to group A (P < 0.05). The incidence of adverse reactions between the two groups was similar (P > 0.05). Conclusion: Relatively elevated intravenous dosage of remifentanil with PCA during the active phase in the first stage of labor is safe and more effective than a fixed-dosage regimen for labor analgesia. Trial Registration: This study was registered with ChiCTR on 24/08/2021 with trial identification number: ChiCTR2100050247. First participant was recruited on 31/08/2021. The last patient was recruited on 12/08/2022.