Pharmacodynamics And Safety Of Ropivacaine For Spinal Anesthesia In Patients Undergoing Cesarean Section

Background and ObjectiveSpinal anesthesia is currently the first choice for cesarean section because of its rapid onset and exact effect. Compared with bupivacaine, ropivacaine is(1)the toxicity of central nervous system and cardiac is low;(2)the Fat-soluble is low, the motor nerve block is weak and the applications is more secure, so it is more and more used in clinical. Binding to its receptor, Opioid can stimulate the release of endogenous opioid peptides, it can also inhibit the sympathetic nerve to reduce the release of norepinephrine, so that to enhance the threshold of body pain. Ropivacaine alone for cesarean section, even when the block level is not low, still can not avoid the traction causes of maternal discomfort and anxiety. The aim of this study was to investigate the pharmacodynamics and safety of ropivacaine of different dosage used for spinal anesthesia for patients ungoing cesarean section; the effect of sufentainil to ropivacaine in quality of block for lumbar anesthesia, thereby providing an important reference for clinical anesthesia.Materials and Methods1Subjects and groupsAll the patients who underwent improved cesarean section were selected, the entry criteria for this study included full-term singleton primipara pregnancies (ASAⅠ-Ⅱ),age21-38years old, weight56-91kg,no placenta previa, fetal abnormalities and other pathological obstetric factors, no spinal anesthesia contraindications and no allergy of local anesthetics and opioid drug.(1)The group of different doses of ropivacaine:all the90cases were divided into three groups according to the dose, each30cases:0.5%ropivacaine llmg (A group);0.5%ropivacaine12mg(B Group);0.5%ropivacaine14mg(C group).(2)The group of combining with sufentanil:the total of90cases randomly divided into three groups, each30cases:0.5%ropivacaine12mg(A group);0.5%ropivacaine12mg combined with2.5ug sufentanil(B Group);0.5%ropivacaine12mg combined with5ug sufentanil(C group).2Anesthesia methodsIntramuscular injection of atropine0.5mg to all the maternal before entering the operating room, then injecting hydroxyethyl starch300-500ml, after left lateral position, all patients were administrated the mixture after the success with L2-3spinal puncture in0.1ml/s, then placing epidural catheter to head with the length of4cm and adjusting the operating table to15degrees after turnning supine.3Assessment of pharmacodynamicsSensory block:testing the absence of pain with pin-prick in the left anterior axillary line, monitoring once every minute in15minute and once every3min15minute later to a fixed plane after injecting, then once every30min until the return to normal. Recording the onset time, the level to peak spread, the time to peak spread and maintenance time, the time of operate the postoperative analgesia should be record for the sufentanil group. Motor block:it was evaluated by using a modified Bromage scale, monitoring once every minute in10minute and once every3min10minute later to the peak Bromage scale after injected, then once every15-30min to the lowest Bromage scale. The onset time, the level to peak spread, the time to peak spread and maintenance time demanded be observed and recorded. 4Assessment of the function of circulatory and respiratoryMultifunction monitor were connected and SBP,DBP,MAP,HR,SPO2and ECG of injection time,5min,10min,20min,30min,60min after injecting were monitored and recorded continuously. All groups were required to record1min,5min Apgar score of neonates.5Assessment of Apgar scoreAll groups were required to record Apgar score of neonates at1min,5min.6Assessment of anesthesia efficacyThe grade of anesthesia efficacy:excellent:without stretch felling or slight pulling but no pain or other discomfort, muscle relaxation and excellent analgesia; good:it felt comfortless when pulling periton, checking up uterus, and so on, but without medication because of the short period of time and the light degree, muscle relaxation was somewhat less; medium:intravenous administration was necessary for the poor analgesia, strained abdominal muscle and obvious pulling; Poor:for the poor analgesia, lidocaine was needed.7Assessment of adverse reactions(1)The incidence of hypotension, bradycardia, nausea, vomiting, chest tightness, chills should be recorded in the group of different dose of ropivacaine and the group of combining with sufentanil;(2)The group of combining with sufentanil demanded to monitor the occurrence of itching and respiratory depression.8Statistics analysisStatistical package (SPSS13.0) was adopted for our issue, meand±standard deviation was used to express the numerieal date and the K-S and Levene were employed to operate test of normality and homogeneity of variance for the comparion in groups, in accordance with the two test ANOVA was utilized, otherwise being applied rank sum test, chi square test was used to express classified variable. The detection level is considered statistically a=0.05. Results1Pharmacodynamics and safety of ropivacaine of different dose groupsSensory block:Compared with group A, the level to peak sensory block of groupB and C increased gradually (P<0.05).The level to peak sensory block of group C was higher than that of group B (P<0.05).The maintenance times of group B and C prolonged significantly (P<0.05). Motor block:compared with group A, The onset time and the time to peak motor block shorten significantly, the maintenance times prolonged, the incidence of Bramage3level increased in group B and C (P<0.05).The rate of excellent and good was87%(group A),93.3%(group B),100%(group C), anesthesia efficacy of group B and C were significantly better than that of group A. The function of circulatory and respiratory:after injection, the MAP decreased significantly at T1,T2,T3in groupB and at T1,T2,T3,T4in group C, referring to HR, the group B increased in T1(P<0.05),while the group C raised in T1,T2.Compared with group A, HR increased in group B in T1,MAP decreased significantly at T1,T2,T3,T4(P<0.05) and HR inceresed in T1T2in group C. Compared with group B, HR rased in T2and MAP decreased significantly in T1and T2in group C(P<0.05).Spo2fluctuationed in95%-99%and ECG was without myocardial ischemia and arrhythmia. The lmin,5min apgar scores were in the normal range and no different between the three groups (P<0.05).Adverse reactions:The incidence of hypotension, nausea, vomiting,chest tightness and the dose of ephedrine incerased in group B and C(P<0.05).2Pharmacodynamics and safety of ropivacaine combined with sufentanilSensory block:compared with group A and B,the time to peak level was shortened, the maintained time and PC A time was prolonged in group C(P<0.01). Motor block:there were no significant differences in the onset time,maintained time,the time to peck motor block and the incidence of Bromage3level. The rate of excellent and good:26.7%,66.7%(group A);46.7%,50.0%(group B);90.0%,10.0%(group C).The function of circulatory and respiratory:The MAP reduced in T1、T2、 T3in all the group after injection(P<0.05),while HR increased in TI in group A and B. SpO2fluctuationed in95%-99%and ECG was without myocardial ischemia and arrhythmia. The1min,5min apgar scores were in the normal range and no different between the three groups (P<0.05).Adverse reactions:comparing with group A, the incidence of pruritus lessened and that of chill raised (P<0.01), while the rate of pruritus in group C was more than that in group B.Conclusions1. The best dose for spinal anesthesia is0.5%ropivacainel2mg, because of the better anesthesia efficacy and the slight effect to function of circulatory and respiratory for maternal.2. After adding5ug sufentanil to0.5%ropivacaine, the anesthesia efficacy is better, traction reaction is light and it have no effect to the circulatory and respiratory functions, so it is suitable for maternal application.