Discussion
Excessive uterine contractions, reduced uterine contractions, anxiety, pain
CONSTRICTION, PLACENTAL ABRUPTION, ADVERSE EFFECTS, FETAL DISTRESS
The key findings of our study were that pretreatment with low-dose intranasal dexmedetomidine (IND) as an adjunct with the initiation of epidural labor analgesia provided a quicker onset of analgesia and lower pain scores caused by epidural puncture than conventional epidural labor analgesia (CON).A number of studies have shown that administering DEX intranasally is safe, effective, more comfortable and convenient than an intravenous approach [The nasal mucosa is rich in capillaries, and intranasal DEX administration results in the rapid entry of the drug into the bloodstream [This research showed that the median onset time of traditional PIEB with ropivacaine and sufentanil was 10.0 (8.5 to 11.5) minutes, consistent with the results of Song et al. [The main purpose of this study was to observe the initiation of labor analgesia; therefore, the data were only collected during the first 60 min of this study. VAS scores were decreased in the IND group in the first 30 min, but no significant difference was seen 60 min post-analgesia, which suggested that IND improved the initiation of analgesia without affecting the maintenance of analgesia. A higher RSS was found in the IND group, which suggested that IND might reduce the stress and anxiety of parturients during labor. DEX has also been confirmed to improve sedation during the later stages of labor via epidural administration [In this study, the median difference in the onset of analgesia between the CON and IND groups was 4 min. Wang et al. assumed that any difference should be at least 5 min to be clinically significant [DEX has a biphasic effect on SBP, as it decreases the heart rate and cardiac output via central anti-sympathetic action but increases vascular resistance via peripheral vascular α1-adrenoreceptor activation. Therefore, SBP is decreased and then elevated with increasing plasma concentrations in humans [Excessive uterine contractions might induce fetal distress or placental abruption. Several studies have suggested that DEX enhances uterine constriction [To identify the optimal intranasal dose for providing the best analgesia and sedation while minimizing side effects, three different intranasal doses (0.5, 0.8 and 1.0 μg/kg) were tested in a preliminary experiment according to methods used in previous studies. We found that dosages of 0.8 and 1.0 μg/kg reduced uterine contractions and extended the first stage of labor. This result was inconsistent with a previous study [This study had several limitations. First, the study was a single-centre study, and the sample was representative but not large. Second, the optimal dosage was not selected using a sequential method, which may reduce the power of the study. Third, the population was young women (27.9 ± 2.8 and 27.3 ± 2.9), which accounts for the majority of current primipara undergoing vaginal delivery, while the population of “older mothers” has increased in recent years and should be further studied. Finally, only data from 60 min post-IND were collected to assess the effect of IND on onset time and procedural pain. Whether IND has advantages in the maintenance of analgesia and breakthrough pain should be explored in future studies.In summary, pretreatment with intranasal low-dose dexmedetomidine as an adjunct to a programmed intermittent epidural bolus might provide faster analgesia onset and less pain during the epidural puncture without increasing adverse effects compared to the traditional PIEB mode. These findings suggest that pretreatment with IND could be a useful adjunct for some patients during the initiation of epidural analgesia, and further investigation should be encouraged to determine its utility more fully.