Feasibility Analysis Of PI Difference Between Upper And Lower Limbs In Supine And Lateral Position As Predictors Of Hypotension After Combined Spinal Epidural Anesthesia In Cesarean Section

BackgroundCombined spinal epidural anesthesia(CSEA),which has advantages of both epidural anesthesia and subarachnoid anesthesia,is widely used in cesarean section surgery.Hypotension is one of the most common complications,which can cause a series of maternal and fetal adverse reactions.Thence the technologies of preventive monitoring of maternal hemodynamics and management methods have gradually improved in recent years.Perfusion index(PI)refers to the ratio of the amount of light absorbed by peripheral pulsatile and non-pulsatile tissues,which is continuously measured using a pulse oximeter.PI stands for the state of microcirculation innervated by sympathetic nerves and is considered as a monitoring indicator of systemic vascular resistance(SVR).The studies found that a higher baseline PI value of the finger in the supine position could predict the occurrence of hypotension caused by CSEA during cesarean section,and the baseline PI value of the toe in the supine position was negatively correlated with the occurrence of hypotension after CSEA.However,the relationship between the baseline PI difference of the upper and lower limbs in the supine position(SP)or lateral position(LP)and maternal hypotension after CSEA is still unknown.ObjectiveThis study was to explore the accuracy and feasibility of baseline PI differences between upper and lower limbs under different positions as the predictors of hypotension after CSEA for materal undergoing selective cesarean section,in order to provide a reference for clinical intervention.Method255 puerpera who underwent selective lower cesarean section under combined spinal and epidural anesthesia from January 2018 to septemper 2018 were selected.All maternal had no medication before anesthesia,suspined on the operating bed after entering the room.Cardiocap ? monitor was used to monitor heart rate(HR)and blood pressure(BP).The maternal was instructed to relax for 5 minutes,opened the peripheral veins,inhaled oxygen at a mask of 5L/min,and quickly injected 6%hydroxy ethyl starch colloid solution 500ml.Two Masimo Radical 7 pulse oximeters with the same batch were used,whose probes were connected to the left index finger of the maternal hand and the second toe of the left foot.CSEA was performed by an experienced anesthesiologist.The maternal was lying on the left side,L2?L3 was selected as the puncture point.During the operation,the hypotensive parturient woman injected 2mg of methoxamine or 6mg of ephedrine to correct it.Maternal bradycardia was intravenous injected of atropine 0.2mg to treat.HR,systolic blood pressure(SBP),diastolic blood pressure(DBP),mean arterial pressure(MAP)were recorded at each time points during maternal supine(T0),lateral(T1),When hypotension occurred or when blood pressure was lowest from the start of anesthesia to the time of fetal dissection(T2).At T0 and T1,we noted baseline PI of finger extremity(PIf)and PI of toe extremity(PIt),calculated the PI difference between the upper and lower extremity(PId)and the positive value of the difference(PIdp).We also recorded umbilical arterial blood pH,PCO2,PO2,BE,Apgar scores at 1 and 5 minutes after birth,observed of the level of intraoperative and intrathecal sensory block,time from injection to fetal removal,total surgery time,blood loss and infusion volume,neonatal weight,and Apgar scores 1min and 5min after birth,the times of nausea,vomiting,and chest tightness.The basic value of SBP was measured by non-invasive cuff pressure.Hypotension is defined as a 20%reduction in SBP,which is divided into non-hypotension group(N group)and hypotension group(H group).Result1.There were 102 cases of maternal hypotension(41.63%).there was no statistically significant difference between two groups in general clinical data(P>0.05).2.At T0 and T1 between two groups,there was no statistically significant difference in BP and HR(P>0.05),the differences in PI values were statistically significant(P<0.05).3.T0-PId,T1-PId,T0-PIdp,Tl-PIdp and T2SBP had moderate and above correlation(rs were 0.534,0.595,0.585,0.617 respectively).4.ROC curves analysis was performed,T0-PId,T1-PId,T0-PIdp,T1-PIdp were found to be of medium and above diagnostic value(AUC were 0.86,0.898,0.919,0.91 respectively),the lower the PI difference and its absolute values were,the higher the possibility of hypotension(cutoff values were 0.805,0.775,0.805,1.015 respectively),the accuracy were 0.876,0.845,0.837,0.824 respectively,the sensitivity were 0.98,0.794,0.822,0.912 respectively,the specificity were 0.804,0.881,0.804,0.762 respectively.At T0 and T1,there were no statistically significant difference about AUCs between two PIds or two PIdps(P>0.05).At T0,the AUC of PIdp was significantly larger than PId(z=2.362,P<0.05).At T1,there was no significant difference between PId and PIdp about AUCs(P>0.05).5.Taking hypotension(HP)as the dependent variable during maternal surgery,amultivariate logistic regression analysis was analyzed.When T0-PId and T1-PId as covariate analysis,obtained the prediction probability PRE1,the fitting equation was logit(HP)=2.708-1.767*(T0-PId)-2.203*(T1-PId),OR was 0.171 and 0.11(P<0.05).When T0-PIdp and T1-PIdp as covariates,obtained the prediction probability PRE2,the fitting equation was logit(HP)=7.252-5.766*(T0-PIdp)-3.54*(T1-PIdp),OR were 0.003 and 0.029(P<0.05).The greater the logit(HP)was than 0.5,the higher the possibility of hypotension after maternal CSEA.6.ROC curves analysis of prediction probability was performed,AUCs of PRE1 and PRE2 were 0.929 and 0.964(z=2.486,P<0.05),were higher than PId or PIdp alone(P<0.05),the accuracy were 89%and 88.6%,the sensitivity were 0.931 and 0.863(?2=8.1,P<0.05),the specificity were 0.93 and 0.863(?2=7.111,P<0.05).7.The differences in the times of nausea and vomiting and chest tightness between two groups caused by hypotension were statistically significant(P<0.05).Conclusion1.The PI difference and positive value of the upper and lower extremities in the supine position and the lateral position of the selective maternal cesarean section can be an effective indicator to predict maternal hypotension after CSEA.2.The regression equation of the absolute value of the PI difference between the upper and lower extremities of the combined supine and lateral supine positions can be a more effective indicator for predicting maternal hypotension after CSEA.