Study Of Intrathecal Dexmedetomidine Combined With Ropivacaine In Cesarean Section

Objective:To evaluate the effect of intrathecal ropivacaine combined with different doses of dexmedetomidine for cesarean section and to find the optimal dose of intrathecal dexmedetomidine for cesarean section.Methods:120 American Society of Anesthesiologists(ASA)Class I and II parturients were selected to undergo elective cesarean delivery under spinal anesthesia after approval by the hospital ethics committee and written and informed consent of the patients.The parturients were randomly divided into 4 groups of 30 cases each according to the drug regimen applied for anesthesia.Group R: intrathecal ropivacaine 12 mg;Group RD1: intrathecal ropivacaine 12 mg + dexmedetomidine 5 μg;Group RD2:intrathecal ropivacaine 12 mg + dexmedetomidine 7.5 μg;Group RD3: intrathecal ropivacaine 12 mg + dexmedetomidine 10 μg.The maternal anesthetic effects in the 4groups were observed,and characteristics of spinal anesthesia,hemodynamic changes,adverse effects,stress reactions and neonatal outcomes were recorded in the four groups.Results:Maternal demographic characteristics such as age,weight,height and surgical characteristics such as duration of pregnancy,duration of surgery,time of fetal delivery,and intraoperative bleeding were comparable among the four groups with no statistically significant differences(P > 0.05).Patients in Group RD1,RD2 and RD3 had significantly longer sustained sensory and motor block time than patients in Group R.All four groups had comparable onset times of sensory and motor block.The time for the level of sensory block to lower to S1 was longer in Group RD1(411.07±106.66 min),Group RD2(397.03±125.39 min)and Group RD3(468.63±116.43 min)than in Group R(273.60±88.34 min)(P< 0.001).The time to recover from motor block to a Bromage score of IV was longer in Group RD1(353.60.07±137.28 min),Group RD2(350.57±118.01min)and Group RD3(404.67±112.83 min)than in Group R(232.70±93.29)(P< 0.01).The incidence of chills was significantly lower in the Group RD1,RD2 and RD3 than in the Group R(P< 0.001).There was no significant difference in the incidence of adverse effects such as hypotension,bradycardia,nausea,vomiting,hypoxemia and pruritus in the four groups(P>0.05).There was no statistically significant visceral traction response or fentanyl use in the four groups(P>0.05).Phenylephrine dosing was significantly higher in Group RD2 and RD3 than in Group R(P<0.05),and there was no significant difference in phenylephrine dosing between Group RD1 and Group R(P>0.05).None of the newborns in the four groups experienced respiratory depression or heart rates below 100 beats/min.There were no statistical differences in postnatal Apgar scores(1 min,5 min after birth)(P>0.05).No newborn had an Apgar score of less than 9.The postoperative concentrations of β-endorphin(β-EP),cortisol(Cor)and tumor necrosis factor-α(TNF-α)in the Group RD1,RD2 and RD3 were lower than that in Group R(P<0.05).No signs and symptoms of neurological deficit were found in any of the four groups one month after surgery(P>0.05).Conclusion:This study found that intrathecal 5μg of dexmedetomidine as an adjuvant to ropivacaine relieved intraoperative chills,did not increase intraoperative and postoperative adverse effects,did not increase the amount of intraoperative vasoconstrictor used,and prolonged the duration of maternal sensory and motor block,making this dose appropriate for caesarean delivery.