Ultrasound Measurement Of Subclavian Vein Diameter On Assessment Of Maternal Blood Volume For Cesarean Section

Objective:To investigate the predictive value of ultrasound measurement of subclavian vein diameter?dSCV?and collapse index?CI?on hypotension after spinal anesthesia undergoing cesarean section and the influence of subclavian vein collapsible index?SCV-CI?of before anesthesia guided liquid infusion on maternal and fetal of cesarean section.Methods:In the first part,one hundred and twelve patients of elective cesarean section were enrolled,aged20⁴0 years,gestational age 37⁴2 weeks,ASA grade I or II,all parturients were singleton pregnancies.Preoperative fasting for 8 hours and no drinking for 4 hours,entering the operating room intravenous infusion of compound electrolyte injection 10 ml·kg^-1·h^-1.The method of anesthesia is combined spinal epidural anesthesia,puncture space was L₂^L₃,slowly injected 0.5%ropivacaine 2.5 ml into the subarachnoid space,level of anesthesia was controlled in T₈^T₆.The maximum dSCV?dSCVmax?and SCV-CI were measured by ultrasound before and after 10 minutes of spinal anesthesia.Blood gas analysis of umbilical artery after the fetus was taken out and before breathing.According to the occurrence of hypotension after spinal anesthesia,the subjects were divided into two groups:named hypotension group?group H?and no hypotension group?group N?.Pearson correlation was used to analyze the relationship between dSCVmax,SCV-CI and hypotension after spinal anesthesia,and receiver operating characteristic curve?ROC?was used to evaluate the predictive value of dSCVmax and SCV-CI for hypotension.In the second part,according to the threshold value of SCV-CI obtained from the results of the first part,80 parturients were included in the cesarean section.According to the SCV-CI threshold,they were divided into the experimental group?Group S?with the threshold?38.24%and the control group?Group C?with the threshold<38.24%.The anesthesia method is the same as that the first part.At 30 minutes before anesthesia,8 ml/kg of compound electrolyte injection was used to preload the balance fluid in Group S and10 ml·kg^-1·h^-11 in Group C.Blood gas analysis of umbilical artery after the fetus was taken out and before breathing.Results:In the first part,the data of One hundred and twelve subjects were included initially,eleven parturients were excluded from the monitoring process.Finally,the data of One hundred and one parturients were analyzed statistically,44 of them had hypotension,the incidence was 43.6%.Compared with the group without hypotension,dSCVmax decreased and SCV-CI increased in the group with hypotension?P<0.01?.The difference of Lac between the two groups was statistically significant,and it was higher in hypotension group than that in no hypotension group?P<0.05?.The area under ROC curve?AUC?of SCV-CI were 0.871 and 0.914,the sensitivity were 70.45%and 93.18%,the specificity were96.49%and 98.25%,the cutoff values were 38.24%and 37.68%,respectively.Before and after anesthesia for predicting hypotension after spinal anesthesia,the AUC of SCV-CI were 0.871 and 0.914,with sensitivity were 70.45%and 93.18%,specificity were 96.49%and 98.25%and optimal cutoff values were38.24%and 37.68%,respectively,which had statistical significance.The AUC of dSCVmax before and after spinal anesthesia were 0.806 and 0.903,the sensitivity were 80.84%and 75.00%,the specificity were57.89%and 94.74%,the cutoff values were 8.0 mm and 6.5 mm,respectively.In the second part,80 parturients were included initially,10 cases were excluded from the monitoring process,and the data of 70 parturients were statistically analyzed.The incidence was 44.8%of hypotension29 cases in Group S,which had 41 cases,and with the incidence was 46.3%of hypotension 13 cases in Group C,which had 19 cases,the difference was not statistically significant?P>0.05?.Before anesthesia,the volume of liquid infusion was 502.56±81.22 ml in the experimental group was higher than that in the control group,and 301±45.52 ml in the control group,the difference between the two groups were statistically significant?P<0.05?.The general situation of the two groups,the incidence of hypotension after anesthesia,neonatal Apgar score,umbilical artery blood gas analysis,ephedrine,norepinephrine,atropine maternal number comparison,the difference was not statistically significant?P>0.05?.Conclusion:Before and after spinal anesthesia,the SCV-CI was a predictor of hypotension after spinal anesthesia,and SCV-CI after spinal anesthesia was more clinically significant,wherein the threshold of CI was 37.68%.SCV-CI of before anesthesia guiding liquid infusion can not reduce the incidence of hypotension after anesthesia undergoing caesarean delivery women,and not obvious effect on the fetus.