Ultrasound Measurement Of Inferior Vena Cava As A Predictor Of Hypotension Following Spinal Anesthesia During Cesarean Section

ObjectiveUltrasound was used to compare the variation trend of the inferior vena cava parameters during cesarean section in supine position and left lateral position before spinal anesthesia for pregnant women,which is try to find out the mechanism of hypotension following spinal anesthesia and to explore the predictive effect of preoperative parameters of inferior vena cava on hypotension following spinal anesthesia.Method70 parturients,aged 20-40 years old and ASA grade ?-?,scheduled for cesarean section under spinal anesthesia were included.ECG,oxygen saturation and invasive blood pressure monitoring were performed after the parturient entered the operating room.Ringer's Solution was continuously infused at a speed of lOml/kg/h,and the basic blood pressure and heart rate were recorded.The anesthesiologist performs combined spinal-epidural anesthesia or single spinal anesthesia in L3-L4 space,injects 2.5 ml of 0.5%ropivacaine into subarachnoid space,puts into epidural catheter,and injects 2%lidocaime into epidural space when necessary until anesthesia plane reaches T6-T8 plane.If the mean arterial pressure is lower than 60mmHg,or the mean arterial pressure is lower than 70%of the basic value for more than 30s,the parturient is determined to have hypotension following spinal anesthesia.[1]Observers collected images of infernor vena cava,heart rate and blood pressure at different time points.Through retrieval and analysis of images,the diameter and variability of inferior vena cava at each time point were measured,and the ratio of inferior vena cava diameter were calculated.According to the presence or absence of hypotension after spinal anesthesia,the patients were divided into hypotension group(group D)and non-hypotension group(group F).spss23.0 statistical software was used for data analysis.The relationship between inferior vena cava parameters and blood pressure was observed.The ROC curve was used to evaluate the effectiveness of inferior vena cava parameters in predicting hypotension after spinal anesthesia.P<0.05 is statistically significant.Results1.There is no statistical difference in general data between the two groups(P>0.05).2.Compare with T2 in hypotension group,IVCe decreased at T1,T3(P<0.05);IVCCI increased at T1,T3(P<0.05).There is no significant difference of IVCe and IVCCI in non-hypotensive group(P>0.05).3.There is significant difference of IVCe between the two groups at T1,T3(P<0.05).There is significant difference of IVCCI between the two groups at T1,T3(P<0.05).4.The mean arterial pressure is positively correlated with the diameter of inferior vena cava(r = 0.626,P<0.01),and negatively correlated with the collapse index of inferior vena cava(r =-0.604,P<0.01)at T3.5.The A IVCe between T1and T2 can predict the hypotension after spinal anesthesia(P<0.05).A IVCe predict hypotension with a cutoff value of 0.828,sensitivity of 84.2%,and specificity of 80%.The IVCCI of T1 can also predict the hypotension(P<0.05).IVCCI predict hypotension with a cutoff value of 21.84%,sensitivity of 80%,and specificity of 68.4%.ConclusionUltrasonic measurement of the diameter of the inferior vena cava confirmed that the main mechanism of hypotension after spinal anesthesia was the compression of the inferior vena cava.The preoperative parameters of inferior vena cava can predict the occurrence of hypotension following spinal anesthesia.