[Application of dexmedetomidine combined with ropivacaine in the cesarean section under epidural anesthesia]

To explore the anesthetic effect and neonatal effects of dexmedetomidine combined with ropivacaine in the cesarean section under epidural anesthesia.

Between January 2012 and March 2013 at the First Affiliated Hospital with Nanjing Medical University, sixty parturients with a single baby at full term in vertex presentation scheduled for caesarean section under epidural anesthesia, were randomly divided into 3 groups (n = 20 each) according to the random digits table: dexmedetomidine + ropivacaine (RD), fentanyl + ropivacaine (RF) and normal saline + ropivacaine (RN). After identification of the epidural space and a negative aspiration test for blood or cerebrospinal fluid, 15 ml of 0.75% ropivacaine, was administered epidurally in three the groups with addition of 1 µg/kg of dexmedetomidine in RD group, 1 µg/kg of fentanyl in RF group and 2 ml of normal saline in RN group. Recording the mean arterial pressure (MAP) and heat rate (HR) before anesthesia (T(0)), at 10 min (T(1)) and 30 min (T(2)) after the end of epidural administration, and at end of operation (T(3)). Recording the onset time, maximum sensory analgesic level, time to maximum sensory analgesic level, time to two segmental dermatomal regressions, and time to chief complaint of postoperative pain. The modified bromage degrees, sedation scores and traction reaction were also assessed. The Apgar scores at 1 and 5 min were also recorded after delivery, and the blood samples were drawn from umbilical vein for gas analysis.

MAP, HR and the motor block (Bromage scale) were no statistics differences among the three groups (P > 0.05) . Compared with RN group, the onset time and the time to maximum sensory analgesic level were significantly earlier [(6.3 ± 2.4), (8.7 ± 2.3) min vs (10.9 ± 2.7) min; (11.5 ± 3.9), (16.2 ± 4.6) min vs(19.8 ± 5.2) min, P < 0.05], the time to two segmental dermatomal regressions and the time to chief complaint of postoperative pain were prolonged significantly[(22.5 ± 4.6), (18.5 ± 3.9) min vs (13.5 ± 3.8) min; (415 ± 92), (355 ± 86) min vs( 273 ± 68) min, P < 0.05], level of sedation and degree of traction reaction were better in RD group and in RF group, and the incidence of shivering was lower in RD group (5% vs 40%, P < 0.05), the incidence of dizziness was higher in RF group (20% vs 0, P < 0.05). Compared with RF group, the same results were also seen about the onset time, the time to maximum sensory analgesic level, the time to two segmental dermatomal regressions and the time to chief complaint of postoperative pain, and the level of sedation was better, the incidence of drowsiness was lower in RD group. There were no statistics differences about both the blood gas analysis of umbilical vein and the Apgar scores at 1 and 5 min after delivery.

Administration of dexmedetomidine combined with ropivacaine can provide early onset, establishment of sensory anesthesia, much better sedation levels, decrease the degree of traction reaction and the incidence of shivering, and without adverse neonatal effects.