The Effect Of Different Vasoactive Drugs On Hemodynamics After Combined Spinal Epidural Anesthesia For Caesarean Section

ObjectiveHypotension is the most common serious adverse effect of spinal anesthesia for cesarean delivery,can cause maternal nausea and vomiting、flustered、bosom frowsty、dizziness and newborn hypoxia and damage in the brain,harmful to maternal and newborn,and associated with the severity and duration of hypotension,therefore a number of strategies for preventing hypotension have been investigated.The combination of colloid predilation and vasoactive drug preinjection has been recognized as an effective method to prevent and treat hypotension during cesarean section.However,most of the previous studies compared the effects of vasoactive drugs according to the changes of BP and HR,which could not fully and correctly understand the changes of patients’hemodynamics.The vasoactive drugs commonly used to prevent and treat hypotension in cesarean section are ephedrine and phenylephrine,but ephedrine has the effect of resisting fetal acid-base state,and phenylephrine can cause maternal bradycardia and reduce cardiac output,the application of metaraminol in obstetric anesthesia is rarely studied.It is proposed to apply different vasoactive drugs on the basis of colloid preload to prevent and treat hypotension after CSEA for cesarean section,the proposed impedance cardiography（ICG）to observe the effect of treatment and its influence on maternal circulation function,and explore a method to effectively prevent and treat hypotension.Method120 patients who planned to undergo cesarean section in the Chaohu Affiliated Hospital of Anhui Medical University in January and November 2017 were randomly selected,Hydroxyethyl starch in 30 min before anesthesia input 7ml/kg.According to intravenous preinjection of different vasoactive drugs,the patients were randomly divided into 4 groups,with 30 cases in each group.Group A was given metaraminol 0.25mg（2.5ml）,Group B was given ephedrine 7.5mg（2.5ml）,Group C was given phenylephrine 0.1mg（2.5ml）,Group D was given an equal volume normal saline of 2.5ml.Observe entry time（T₁）,enlarged（T₂）,2,5,10min after anesthesia（T₃,T₄,T₅）,cut the skin（T₆）,right after the delivery（T₇）,at the end of operation（T₈）MAP、HR、CO、CI、TFC and SVRI。Record total infusion volume,blood loss,amniotic fluid volume,the incidence of nausea and vomiting,and the Apgar score within 1 min after delivery.ResultsThere was no significant difference of total infusion volume,blood loss,amniotic fluid volume and the Apgar score within 1 min after delivery between the 4groups（P>0.05）;In the bolus group,MAP decreased at T3 and T4 after anesthesia,while HR、TFC did not change,CO、CI increased at T7,and SVRI decreased significantly after anesthesia until the end of surgery;There was no change in MAP in the metaraminol group A,but it was higher in the T3,T4 and T5 groups than in the D group,and HR was slightly slower in the T3 and T4 groups than in the B and D groups,The change in CO、CI was similar to that in the D group,while the change in SVRI was smaller,significantly higher than that in the B and D groups;MAP of ephedrine group B increased slightly at T4 and T5,and was higher than that of group D,with no change in HR、CO、CI increased significantly after anesthesia,and was higher than that of the other three groups,while SVRI was lower than that of group A and C;MAP、CO、CI、SVRI was basically unchanged in the phenylephrine C group,and HR was slightly slowed down at T₃and T₄,which was lower than that in the B and D groups;The incidence of intraoperative nausea and vomiting and the addition rate of vasoactive drugs in group D were significantly higher than those in group A,B and C（P<0.05）.ConclusionICG is safe and accurate for monitoring hemodynamics during cesarean section.Compare with the other three groups,In group A,the fluctuation of MAP、CO and CI was small,HR was slow,and SVRI was significantly increased.The effect of colloid preload combined with metaraminol to preventing and treating hypotension in cesarean section is better and safer.