Effect Of Dexmedetomidine Administration In Cesarean Sectionunder General Anesthesia On Mothers And The Neonates

Objective: To study the effect of dexmedetomidine(DEX) used in general anesthesia for cesarean section(C-section) on mothers and neonates, and to discuss application prospects of dexmedetomidine administration in obstetric anesthesiaMethods:1 Patients and study protocolSixty patients(aged 22 to 35 years, weighing 60 ~ 80 kg, with ASAⅠ~Ⅱ, singleton pregnancies and gestational age of at least ≥36 weeks) were selected from the Second Hospital of Hebei Medical University between February 2014 and October 2014, to undergo C-section under general anesthesia. The patients enrolled in the study were randomly divided into dexmedetomidine administration group(group D; n=30) and control group(group C; n=30). Exclusion criteria were multiple births, prematurity, severe organ damage, mental disorders, known fetal malformations, fetal distress and the experimental drug allergy. All experiments were approved by the ethics committee of our hospital and all of these patients gave informed consent.2 Experimental Methods:Routinely fasted pregnant women were not given any premedication, who then lied in a supine position or with a left lateral tilt of 15°~20° in the operating room. Peripheral vein infusion of hydroxyethyl starch(130 / 0.4) was initiated at the rate of 20ml/min, followed by Ringer’s lactate solution. In group D, 10 min before induction of anesthesia, intravenous infusion of DEX was given at a loading dose of 0.5μg/kg, which was then maintained at a dose of 0.4 μg/( kg·h). In group N, an equal volume of saline was given. 3min after inhaling pure oxygen through a mask, patients in both groups were prefilled with 8% sevoflurane at oxygen flow rate of 6 L/min; the mask was then closed until CETSev was up to 7.5 percent. The patients were asked to take a deep breath following spirometry method. Rapid induction was made with propofol of 1~1.5mg/kg and rocuronium of 0.4mg/kg when BIS value was 60. The appropriate laryngeal mask(Supreme laryngeal mask with size 3 to 4) was inserted 2min after that, immediately followed by insertion of gastric tube for decompression and drainage. The anesthesia machine was then connected for mechanical ventilation, and tidal volume and respiratory rate were adjusted to maintain end-tidal carbon dioxide partial pressure of 30~35 mm Hg. Then end-tidal CETSev of 1.2~1.3% sevoflurane and 2L/min of pure oxygen was applied until neonates were delivered. When all patients were inserted with laryngeal mask, the surgery was initiated with skin incision by surgeons. After the baby was delivered and the umbilical cord was cut, deep anesthesia was performed with midazolam of 0.04 mg/kg, sufentanil of 0.3μg/kg, and pumped propofol of 4~12 mg/( kg·h). Sevoflurane concentration and propofol infusion rate were afterwards adjusted according to the BIS value and maternal vital signs, maintaining BIS value of 45 to 55. Maternal arterial pressure(MAP), heart rate(HR), bispectral index(BIS), and other indicators, such as plasma epinephrine, plasma epinephrine and norepinephrine concentration were recorded prior to intravenous drug test(T0), immediately after dexmedetomidine infusion(T1), after induction of anesthesia(T2), immediately after insertion of a laryngeal mask, as well as at skin incision(T3) and at delivery of the fetus(T4). Duration between administration and delivery of the fetus was documented as well. Umbilical arterial blood was taken immediately after the baby was delivered and umbilical cord was cut for blood gas analysis and blood lactic acid determination. The Apgar score was recorded at 1 and 5 min after delivery; and neonatal behavioral neurological assessment(NBNA) scores were also documented at 3d after birth and 7d by neonatologists.Results:1 Age, body weight and gestational age of a total of 60 patients in both groups were not statistically significant(P>0.05). Durations between induction and the fetus delivery were less than 10 min. Two indicators in two groups at T0 was not statistically significant(P>0.05). In induction process, time of BIS up to 60 and dosage of propofol in group D was significantly less than those in group C, and the difference was statistically significant(P<0.05).2 Maternal data:Blood pressure(BP): Based on intra-group comparison, BP at T0 in all patients was lowered compared with that at T2, and the difference was statistically significant(P<0.05). BP at both T3 and T4 in both groups were elevated, compared with that in T0 and T2, and BP in group C was increased more significantly. There was statistically significant difference(P<0.05).HR: According to comparison between the two groups, HR at T1 ~ T4 in group C was significantly higher than that in group D, and there was statistically significant difference(P<0.05). HR at T3 in two groups was relatively elevated compared with that at T2 and T0, but more significantly elevated HR was observed in group C. The difference was statistically significant(P<0.05). HR at T4 recovered to preoperative levels in Group D, but was still higher than preoperative level in group C.Emergency indicators: Plasma norepinephrine and epinephrine at T3 and T4 in the two groups were increased compared with those at T0, and the difference was statistically significant(P<0.05). Those in group C was significantly higher in group C than in group D, and the statistically significant difference was observed(P<0.05).Deep anesthesia measurement: BIS values of patients at T2 ~ T4 were lower than those at T0 in both groups(P<0.05), and BIS values in group D was significantly lower than those in group C. Therefore, the differences were statistically significant(P<0.05). Compared with those at T0 in group D, BIS values were decreased at T1(P<0.05), as compared with those at T1 in group C.3 Neonatal data: Neonatal Apgar and NABA scores at 3d after delivery and 7d as well as umbilical arterial blood gas analysis showed no significant difference in both groups(P>0.05).Conclusion:Dexmedetomidine serves as an adjuvant drug in C-section under general anesthesia. Dexmedetomidine administered at a loading dose of 0.5 μg/kg before induction and then maintained at a dose of 0.4 μg/( kg·h) could reduce dosage of intraoperative propofol, improve hemodynamic stability in patients and reduce the stress response resulting from intubation and surgical stimulation. Apgar score and NABA scores were within normal range, and no significant respiratory depression and other adverse reactions were observed.