The Effect Of Ultrasound Measured Inferior Vena Cava Parameters On Blood Volume Evaluation During Combined Spinal And Epidural Anesthesia

ObjectiveTo observe if ultrasound measurement of inferior vena cava could reflect the change of volume status and predict the hypotension caused by combined spinal and epidural anesthesia(CSEA),and its significance for the responsiveness of fluid therapy.MethodsOne hundred and five patients were randomly divided into three groups of 35 each,named control group,crystal liquid and colloidal solution group.Patients with ASA 1-2,aged 18-75 years were included.Standard monitors of electrocardiography,pulse oximetry(Sp02)and the non-invasive blood pressure(NIBP)were applied and the intravenous access was established after they entered the operating room.All patients received Lactate Ringer injection 10 ml/kg/h.The blood pressure and heart rate was recorded after 5 minutes.The inferior vena cava diameters during expiration(IVCe)and inspiration(IVCi),abdominal aorta diameter(Ao)and left ventricular ejection fraction were measured by ultrasound before anaesthesia.Then the collapsibility index(CI)and IVCe/Ao was calculated as a base line.CI was calculated as[(IVCe-IVCi)/IVCe×100%].Then the patients mixed to receive the standard CSEA,which is required to have the lateral position.Spinal anesthesia was induced with 1%ropivacaine 1.5 ml and cerebrospinal fluid lml.The injection duration was 10 to 15 seconds.All patients were lying supine and spontaneously after anesthesia.Within the following 30 minutes after the completion of CSEA,blood pressure,heart rate,anesthesia level,IVCe,IVCi,CI,Ao and left ventricular ejection fraction were measured and recorded every 5 minutes.The crystalline group patients received Sodium Lactate Ringer’ s Injection 8ml/kg during 20 minutes after induction of spinal anesthesia 10 minutes.The colloid group patients received Hydroxyethyl starch Injection 8ml/kg within 20 minutes when drug was injected in the subarachnoid space.The control group patients received Lactate Ringer injection at a rate of 10 ml/kg/h.Patients received phenylephrine 0.05mg when systolic blood pressure dropped below 90 mmHg.Another 0.05mg phenylephrine would be given to the patient if the systolic blood pressure was below 90 mmHg after two minutes.In this research,bradycardia was defined as heat rate less than 50 times per minute,which would be treated with 0.5mg atropine.Symptoms like Nausea and vomiting,chills and dizziness and dosage of phenylephrine and atropine were recorded.A Statistical Package for Social Sciences(SPSS)version 23 was used for data analysis.Independent-sample t-test was applied for quantitative variables like age,weight,height and BMI.Chi-square was applied for qualitative variables like ASA physical status and spinal induced hypotension.Repeated measures were used to analysis HR,SBP,IVCe、IVCi、CI and IVCe/Ao.Receiver operating characteristic curve analysis were used to evaluate IVCe、IVCi、CI and IVCE/Ao in the diagnosis of the hypotension after CSEA.ResultsThere is no statistically significant difference of general data between each group.Compared with Control group,the incidence of hypotension,nausea and vomiting had no statistically significant difference in crystal liquid group and colloidal solution group(P<0.05).The incidence rate of shivering in the crystal liquid group and colloidal solution group were significantly higher than the control group(P<0.05),while had no statistical difference between crystal liquid group and colloidal solution group(P<0.017).Compared with before.anesthesia,the IVCe was decreased and CI was larger 10 minutes after anesthesia(P<0.05).After fluid therapy,the IVCe was increased and CI was decline in the crystal liquid group and colloidal solution group(P<0.05).Compared with before anesthesia,the IVCe,IVCi and IVCe/Ao was decreased and CI was increased at 10 minutes after anesthesia(P<0.05).After fluid therapy,the IVCe,IVCi and IVCe/Ao was increased and CI was decline in the crystal liquid group and colloidal solution group(P<0.05).The IVCe,IVCi and IVCe/Ao before anesthesia can be used to predict hypotension after anesthesia.When the threshold value of IVCe was 1.35cm,the specificity was 63.4%and the sensitivity was 81.8%.When the threshold value of IVCi was 0.73cm,the specificity was 57.1%and the sensitivity was 81.8%.When the threshold value of IVCe/Ao was 0.86,the specificity was 61%and the sensitivity was 100%.ConclusionUltrasound measurement of IVCe,IVCi and IVCe/Ao can reflect the change of volume status after intravertebral anesthesia and fluid therapy.The IVCe,IVCi and IVCe/Ao,to a certain extent,can predict hypotension after intravertebral anesthesia.The ROC curve analysis demonstrated good diagnostic accuracy when using the IVCe/Ao.The optimal cutoff value of IVCe/Ao was 0.86,with a sensitivity of 100%and a specificity of 61%.