Clinical study on labor pain relief using the combined spinal-epidural analgesia and inhaling nitrous oxide.

Objective: To study the pain relief effectiveness of the combined spinal-epidural analgesia (CSEA) and the inhalation of nitrous oxide, and the influences on the mothers and infants.

Methods: The 300 cases of pregnant women were randomly divided into 3 groups: CSEA group, nitrous oxide group and control group. The nitrous oxide group was that pregnant women inhaled nitrous oxide premixed with oxygen (50%:50%), the pregnant women of the CSEA group were injected fentanyl and bupivacaine in the subarachnoid and epidural space, analgesic was not used in the control group. The degree of labor pain, duration of the labor, way of delivery, bleeding volume, rate of anoxia of newborn, blood gas analysis to maternal radius artery and fetal umbilical blood among 3 groups were observed.

Results: The effect for analgesia labor of the CSEA group was much better than that of the nitrous oxide group (P < 0.01). In the first stage of labor and total stage of labor, the CSEA group was shorter than the others (P < 0.05), but there was no difference between the nitrous oxide group and the control group (P > 0.05). In the second stage of labor, the 3 groups were alike to each other. The bleeding volume of caesarean section (373 +/- 77) ml in the nitrous oxide group was much more than the other 2 groups, there was no difference between the CSEA group (259 +/- 78) ml and the control group (239 +/- 89) ml. The rate of obstetric forceps of CSEA group was higher than the control group (P < 0.01), and the rate of caesarean section of the nitrous oxide group was much higher than the CSEA group. The blood gas analysis to maternal radius artery and fetal umbilical blood and the rate of anoxia of newborn of 3 groups revealed no significant difference.

Conclusions: The effectiveness of the combined spinal-epidural analgesia CSEA for analgesia labor is confirmed and has rarely side-effect, and it can be the first choice, and the inhalation of nitrous oxide can safely provide effective labor analgesia, too.