Risk Factors Of Maternal Hypotension After Intrathecal Anesthesia For Caesarean Section

Objective To evaluate high risk factors of hypotension after intrathecal anesthesia for elective caesarean section,and established forecasting model.Methods 171 patients undergoing elective caesarean section from Anesthesia Department of the First Hospital of Wannan Medical College during November 2015 to November 2016,were prospective analyzed.Those patients were divided into Hypotension group(H)and No Hypotension group(N)according to maternal systolic blood pressure less than 90 mmHg or mean arterial pressure lower than 20% after anesthesia induction to fetal disengagement.The following factors were evaluated: age,baseline heart rate(BHR)and Systolic blood pressure(BSBP),pre-gestational body mass index(PBMI)and third trimester of pregnancy body mass index(BMI),weight gain during pregnancy(WGDP),height of uterus and maternal abdominal circumference,gestational weeks,multiple gestation,anesthesia,fasting time,biparietal diameter,femur length,birthweight,complication,etc.Univariate factor analysis verified the independent variables was used into the Multivariate logistic regression analysis to find the predictors of hypotension after intrathecal anesthesia for elective caesarean section.We established forecasting model to predict hypotension,described the receiver-operating characteristic curve(ROC curves)and worked out the area under ROC curve(AUC).Results The incidence of hypotension after intrathecal anesthesia for elective caesarean section was 46.2%(79/171).Univariate analysis showed that the incidence of Hypotension in maternal age is compared between two groups(P=0.069),BHR(P=0.001),WGDP(P=0.046),PBMI(P=0.008),and anesthesia(P=0.024),the difference was statistically significant.Multivariate Logistic regression analysis showed that BHR(P=0.001),weight gain during pregnancy(WGDP),and pre-gestational body mass index(PBMI)as important risk factors to predict the hypotension of caesarean section after intrathecal anesthesia.Logistic regression equation is: Y=-6.802+0.039xBHR+0.189xPBMI-0.080 xWGDP.According to the ROC curves,the area under the ROC curves(AUC)was 0.711,The sensitivity and specificity of judge model in predict hypotension was 85.5% and 49.4% respectively,with 95% confidence interval 0.633 to 0.789.Conclusion Hypotension during intrathecal anesthesia for caesarean section remains a problem.Baseline heart rate,pre-gestational body mass index,and weight gain during pregnancy as important risk factors to predict the incidence of hypotension after intrathecal anesthesia for elective caesarean section.