| Objective:To evaluate the effect of different infusion rates of methoxamine on the mother and baby during cesarean section,and calculate the ED50 of methoxamine in the treatment of hypotension during cesarean section.Methods:After the approval of the Jilin University Committee and informed consent of the patient’s family,choose a maternal woman who meets the inclusion criteria and is scheduled to undergo cesarean section under CSEA.In the first part of the experiment,80 women were randomly divided into 4 groups,namely,control group C and experimental group M2,M3,and M4 groups,20 cases in each group.In the second part of the experiment,the ED50 of hypotension in cesarean section was measured by sequential method according to the results of the first part.After the maternal into the operating room,the peripheral veins of the upper limbs were opened,and routine monitoring was performed.The systolic blood pressure and heart rate values were measured continuously in a calm state,and the average value was taken as the basal systolic blood pressure and heart rate value(T0).After the successful of puncture,the weight of bupivacaine was injected according to the Harten meter,and methoxamine or normal saline was started 1 to 2 minutes before the spinal anesthesia administration.At the time of intrathecal injection,10ml/Kg Sodium Acetate Ringer’s Injection was rapidly injected.During the period from the spinal anesthesia to the delivery of the fetus,when the maternal SBP decreased by more than 20% of the baseline value,the hypotension was recorded and a single intravenous bolus of 1 mg of methoxamine was given.When the maternal SBP increased by more than 20% of the baseline value,it was recorded as high blood pressure while stopping the pumping of methoxamine until SBP less than baseline value restarted pumping,maintain blood pressure fluctuations within 20% of base values.Bradycardia(HR <50 beats/min)was a rescue bolus of atropine 0.2~0.5 mg as appropriate.Firstly recorded the basic(T0)SBP and HR,and then the SBP and HR were monitored and recorded 1 min(T1),3 min(T2),5 min(T3),10min(T4)after spinal anesthesia,1 min before the neonate was born(T5).The incidences of hypotension,hypertension,nausea and vomiting,bradycardia of the parturients were recorded;Record the time from the patient’s spinal anesthesia to the delivery of the fetus,the time from the surgical incision to the delivery of the fetus,the time from the uterine incision to the delivery of the fetus,and the total time of surgery.The total infusion volume,bleeding volume,and methoxamine dose were recorded.The umbilical arterial blood PH,PO2,PCO2,BE,and Apgar scores at 1 min and 5 min after birth were recorded.Results:1、There were no significant differences between the general data of the patients and the blood gas analysis values of the fetal umbilical arteries(P>0.05).2、The incidence of hypotension,nausea and vomiting in group C and M2 was higher than that in group M3 and M4(P<0.001).The incidence of hypertension in M4 group was higher than the other three groups(P<0.001).The incidence of bradycardia was higher in the M4 group than the other three groups,and higher in the C group and the M2 group than the M3 group(P<0.01).3、Systolic pressure changes,intragroup comparison: the SBP was lower than T0 at the time of T1~T5 in group C,and the difference was statistically significant(P<0.05);the SBP of M2 group was lower than T0 at T1-T4,and the difference was statistically significant(P<0.05);there was no significant difference in SBP at each time point in the M3 group(P>0.05);the SBP of M4 group was higher than that of T0 at T3-T5,and the difference was statistically significant(P<0.05).Comparison between groups: At T1,the blood pressure of M2 group was higher than that of C group,and the difference was statistically significant(P<0.05);SBP of M3 group was higher than that of C group from T1 to T4,and the difference was statistically significant(P<0.05);SBP of M4 group was higher than that of C group from T1 to T5,and the difference was statistically significant(P<0.05);the SBP of M3 group was higher than that of M2 group from T2 to T4,and the difference was statistically significant(P<0.05);the SBP of M4 group was higher than that of M2 group from T2 to T4,and the difference was statistically significant(P<0.05);the SBP of M4 group was higher than that of M3 group at T4,and the difference was statistically significant(P<0.05).4、Heart rate changes,intragroup comparison: The heart rate of C group was higher than T0 at T1,and heart rate was lower than T0 at T4~T5,the difference was statistically significant(P<0.05);M2 group had lower heart rate at T3~T5 than T0,the difference was statistically significant(P<0.05);the heart rate of M3 group was lower than T0 at T4~T5,the difference was statistically significant(P<0.05).the heart rate of M4 group was lower than T0 at T2~T5,the difference was statistically significant(P<0.05).Comparison between groups: The heart rate of M2 group was lower than that of C group at T1 and T5,the difference was statistically significant(P<0.05).The heart rate of M3 group was higher than that of C group at T3,the difference was statistically significant(P<0.05).The heart rate of M4 group was lower than that of C group at T1~T2 and T4~T5,the difference was statistically significant(P<0.05).The heart rate of M3 group was higher than that of M2 group at T3 and T5,the difference was statistically significant(P<0.05).The heart rate of M4 group was lower than that of M2 group at T2 and T4,the difference was statistically significant(P<0.05);The heart rate of M4 group was lower than that of M3 group at T2~T5,and the difference was statistically significant(P<0.05).5、The total dose of methoxamine was higher in the experimental group than in the C group(P < 0.05).M4 group had the highest dosage(P< 0.05).The most frequent addition of methoxamine is group C,followed by group M2.6 、 The ED50 results of pumping methoxamine in the treatment of hypotension during cesarean section were: 2.595μg.kg-1.min-1(95%CI :2.082~3.021).Conclusion:1、The women who underwent cesarean section under combined spinal and epidural anesthesia,the choice of 3 μg.kg-1.min-1 dose of methoxamine is a suitable pumping rate at which the maternal hemodynamic fluctuations are small.The incidence of adverse reactions is low and has no significant effect on the fetus.2、The half-effective amount of pumping methoxamine in the treatment of cesarean section is: 2.595μg.kg-1.min-1(95%CI:2.082~3.021). |
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