Dexmedetomidine as a dose of 0.5 µg/mL can be the optimal dose for parturient women in epidural labor analgesia when combined with 0.1% Ropivacaine.

Labor pain is widely managed by epidural labor analgesia which is considered as a standard technique for managing labor. In this technique, Ropivacaine is administered because of less motor block and stable hemodynamics.  Dexmedetomidine, a α2-agonist for α2-adrenergic receptors, exhibits both analgesic and sedative properties without respiratory depressant effect. It can be added to local anesthetic agents to increase the positive effect without increasing the incidence of side effects. Dexmedetomidine has been successfully used in various experimental and clinical studies for neuraxial block and epidural block with fewer side effects. It has been approved for intravenous use only.

Rationale behind the research:

There is a lack of evidence regarding the use of Dexmedetomidine in the obstetric population, and the optimal dose of epidural Dexmedetomidine combined with Ropivacaine for labor analgesia is still uncertain.

Objective:

To assess the effect of Dexmedetomidine in combination with Ropivacaine during the labor analgesia.

Outcome measures

The onset of epidural anesthesia, stages of labor, pain assessment using a visual analog scale (VAS), hemodynamic parameters, fetal heart rate, Apgar scores, level of sedation using Ramsay level of sedation scale and umbilical artery pH. 

Time Points: Baseline and after 30 minutes

Study outcomes

Baseline: There were no statistically significant differences between the groups.

• The addition of 0.25, 0.5, and 0.75 μg/mL of dexmedetomidine to 0.1% ropivacaine provided safe and effective analgesia, but 1 μg/mL of dexmedetomidine resulted in increasing incidence of motor block (Fig1)
• The hemodynamic data, blood loss, mode of delivery, time of stage of labor, and onset time of analgesia were not considerably different between the four groups
• Neonatal Apgar score, umbilical artery pH, and umbilical artery PaO2 were similar in the four groups with no significant differences

Figure 1:  Comparison of analgesic efficacy between the groups.

It is known that Dexmedetomidine addition can lead to the increased potency of epidural Ropivacaine and further decreases the requirement of other analgesics. In this study, a comparative analysis was carried out between different doses of Dexmedetomidine in addition with Ropivacaine. The analysis concluded 0.5 µg/mL as the optimal dose of epidural Dexmedetomidine.

Dexmedetomidine addition to Ropivacaine increases the analgesic effects without increasing the incidences of side effects. Dexmedetomidine exhibits higher selectivity for the α2 receptor that is the potential cause for its effectiveness as a good analgesic and sedative. Fentanyl can lessen the concentration of epidural Ropivacaine and reduce the requirement of Ropivacaine for epidural labor analgesia. It was found that Dexmedetomidine causes less pruritus, less nausea and vomiting than Fentanyl during epidural labor analgesia. Thus, it can be safely used for epidural labor analgesia.

The results also indicated that efficacy of 1 µg/mL of Dexmedetomidine was better than other groups, but the side effects of this group were more. The motor block could occur probably when 0.75 µg/mL or 1 µg/mL of Dexmedetomidine was used for epidural labor analgesia. There were no significant differences observed in SpO₂ and umbilical artery PaO₂ between the groups during labor. There was no incidence of respiratory depression observed despite good sedation with the addition of Dexmedetomidine that leads to wide safety margins. Ramsay sedation scores were measured to calculate analgesic effects between different groups, and there was no occurrence of excessive sedation scores. In conclusion, it can be inferred that 0.5 µg/mL of dexmedetomidine may be the optimal concentration for epidural labor analgesia.