Regular intermittent bolus provides similar incidence of maternal fever compared with continuous infusion during epidural labor analgesia

Objectives:

To compare the effects of regular intermittent bolus versus continuous infusion for epidural labor analgesia on maternal temperature and serum interleukin-6 (IL-6) level.

Methods:

This randomized trial was performed in Nanjing Maternity and Child Health Care Hospital, Nanjing, Jiangsu Province, China between October 2012 and February 2014. Either regular intermittent bolus (RIB, n=66) or continuous infusion (CI, n=66) was used for epidural labor analgesia. A bolus dose (10 ml of 0.08% ropivacaine + 0.4 µg·ml^-1 sufentanil) was manually administrated once an hour in the RIB group, whereas the same solution was continuously infused at a constant rate of 10 ml·h^-1 in the CI group. Maternal tympanic temperature and serum IL-6 level were measured hourly from baseline to one hour post partum. The incidences of fever (≥38ºC) were calculated.

Results:

The incidence of maternal fever was similar between the 2 groups. There was a rising trend in mean temperature over time in both groups, but no statistical difference was detected between the groups at respective time points; maternal serum IL-6 showed similar changes.

Conclusion:

Compared with continuous infusion, regular intermittent bolus presents with the same incidence of maternal fever for epidural labor analgesia. Interleukin-6 elevation could be involved in mean maternal temperature increase.The relationship between epidural labor analgesia and maternal intrapartum temperature was investigated, and several lines of studies found that epidural labor analgesia was significantly associated with maternal fever.1-6 Although an antipyretic effect of opioids and altered maternal thermoregulation partly explain the etiology, inflammation is involved in the most likely mechanism of fever, such as elevation of maternal serum interleukin-6 (IL-6) levels.7,8 Regular intermittent epidural bolus, with smaller local anesthetics consumption and better patient satisfaction compared with continuous infusion, is becoming increasingly used for labor analgesia.9-12 On-demand intermittent epidural injections showed a lower incidence of intrapartum fever in the first 4 hours of labor analgesia than continuous infusion, with similar maternal serum IL-6 levels at respective time points.13,14 However, the association between regular intermittent epidural bolus and intrapartum fever is still unclear. The aim of the present study was to compare the effects on maternal temperature and serum IL-6 level of regular intermittent bolus versus continuous infusion for epidural labor analgesia.