Preoperative Femoral Vessels Variation Predict Hypotension Aftter Spinal Anesthesia For Cesarean Section. An Observational Trial

Objective:To investigate whether femoral vessels variation in different preoperative positions can predict the occurrence of hypotention during cesarean section after spinal anesthesia.Methods:A total of 106 pregnant women,aged 18-37 years,ASA gradeⅠ～Ⅱ,who were scheduled to receive elective cesarean delivery in Chengdu Fifth People’s Hospital from July 2020 to November 2020 were selected.The diameter of the right femoral vein,the diameter of the right femoral artery and the peak flow velocity of the right femoral were measured by ultrasound in the three positions of supine(SP),30 degree tilt left decubitus(LP)and 30 degree tilt right decubitus(RP)one day before surgery,and the change rates of the diameter and flow velocity of the femoral vessels in different positions were calculated.Meanwhile,non-invasive blood pressure(NIBP)and heart rate(HR)in the three positions were recorded.The baseline values of HR and NIBP were measured in the supine position(T1)after 5 minutes of quiet rest after entering the operating room.Subsequently,the women were placed in the left lateral decubitus position,and the L3-4 level was selected for intraspinal puncture.After successful puncture,0.5%ropivacaine(Dilute to 3ml with cerebrospinal fluid)was given in the subarachnoid space.Change the body position to supine immediately after the injection.NIBP and HR were measured every minute,and the anesthesia level wascontrolled at T6 to T4.Hypotension group(group L)or non-hypotension group(group N)were included according to whether hypotension(systolic blood pressure 20%below baseline)occurred after spinal anesthesia.To compare the correlation between the change rate of femoral vessel diameter and blood flow velocity in different positions and the occurrence of hypotension during cesarean section after spinal anesthesia,and draw the receiver operating characteristic(ROC)curve to evaluate the diagnostic efficacy of the change rate of femoral vessel in predicting hypotension after spinal anesthesia.Results:The change rate of femoral vein diameter in the left decubitus Position is a risk factor for hypotension after cesarean section,the change of body weight during pregnancy is a protective factor for hypotension after cesarean section,and the preoperative basal heart rate is a risk factor for hypotension after cesarean section.The incidence of hypotension during cesarean section after lumbar anesthesia was 48.1%.The AUC of the ROC curve predicting hypotension during cesarean section after lumbar anesthesia was 0.627(95%CI:0.508～0.757,P<0.01),the boundary value was 0.059%,the sensitivity was 39%,the specificity was 91.9%,and the maximum approximate index was 0.309.The AUC of the ROC curve for predicting hypotension during cesarean section after lumbar anesthesia was 0.617(95%CI:0.510-0.724,P=0.038),with a cut-off value of 15.75kg,a sensitivity of 47.3%,a specificity of 52.7%,and a maximum approximate index of 0.213.Conclusions:The Change rate of femoral vein diameter in left decubitus position、Weight gain during pregnancy and preoperative basal heart rate are related factors of hypotension after caesarean section.The change rate of femoral vein diameter in the left decubitus position can predict the occurrence of hypotension after caesarean section with lumbar anesthesia,but its sensitivity is low,which is not enough to accurately predict the occurrence of hypotension after caesarean section with lumbar anesthesia.Therefore,it may need to be combined with other predictive methods for comprehensive evaluation in clinical application.