The Value Of Inferior Vena Cava Collapsibility In Postoperative Volume Status Assessment Of Patients Undergoing Major Abdominal Surgery

Objective: Postoperative hemodynamic stability is one of important issues to ensure adequate tissue perfusion and enhance the recovery of critically ill patients after surgery.Insufficient or excessive fluid administration may worsen the outcome of surgical patients in terms of morbidity and mortality.Accumulating evidence has proved the value of inferior vena cava(IVC)ultrasound in evaluating the fluid responsiveness of patients.The aim of this study was to investigate the applicability and accuracy of inferior vena cava collapsibility(d IVC)in predicting fluid responsiveness and provide a reliable index for the assessment of volume status in patients following abdominal surgery.Methods : From May 2018 to December 2018,sixty patients scheduled for abdominal surgery were included in this study at the affiliated Drum Tower Hospital,Nanjing University Medical School.The intraoperative fluid management was determined by the anesthesiologists on their own based on patient's underlying condition,the specific type of surgery and individual clinical experience.After the patients were transferred into anesthesia intensive care unit(AICU),the dimeters of IVC were measured at the end of inspiration and expiration in a breathing cycle and the d IVC was calculated when the patient was in mechanical ventilation or spontaneous breathing after extubation respectively.The fluid challenge test was performed with 5ml/kg of a compound sodium chloride infusion within 15 minutes.The variables of left ventricular outflow tract velocity time integral(VTI),the dimeter of left ventricular outflow tract,cardiac output(CO),and cardiac index(CI)were measure with pulse wave Doppler modality using phased-array probe at apical five chamber view and the responders were identified from non-responders when CO increased 15% above baseline after rapid fluid loading.Simultaneously,hemodynamic parameters including heart rate(HR),mean arterial pressure(MAP),CVP were collected before and immediately after fluid challenge test.Then we assessed the factors influencing the patient's immediate postoperative volume status and compared the hemodynamic parameters of patients before and after fluid challenge test under mechanical ventilation or spontaneous breathing.The effectiveness of each index to predict fluid responsiveness was compared by receiver operating characteristic(ROC)curves and the threshold,sensitivity,specificity and area under the curve ROC(AUC)was calculated.Pearson correlation analysis was created to assess the correlation between each index and CI.Results: A total of 56 patients completed the experiment,including 31 males and 25 females,with an average age of 57.27±8.44 years old.The demographic characteristics of two groups with distinct volume responsiveness during mechanical ventilation or spontaneous breathing were not statistically different.There were no intraoperative parameters reliably predicting the volume status of the patients immediately after operations using univariable logistic regression analysis(p> 0.05).The d IVC was positively correlated with CI(r=0.497,p=0.0001)and the cut-off value of the d IVC was 15.39% with 100% sensitivity and 65.22% specificity to predict fluid responsiveness for patients in mechanical ventilation.The AUC for d IVC was 0.809(95% CI 0.677 to 0.941).The d IVC was positively correlated with CI(r=0.617,p=0.0001)and the cut-off value of the d IVC was 34.15% with 77.78% sensitivity and 80% specificity to predict fluid responsiveness for patients in spontaneous breathing.The AUC was 0.853(95% CI 0.747 to 0.995).The CVP had no close relationship to CI and the AUC for predicting fluid responsiveness was less than 0.8 in both respiratory modes.Conclusion: The inferior vena cava collapsibility can predict fluid responsiveness and guide fluid management for postoperative patients.However,the cut-off value for d IVC is varied under different breathing modes.Therefore,attention should be focused on the patient's breathing mode and other indicators should be integrated to evaluate the fluid responsiveness.Moreover,CVP had limited value in predicting fluid responsiveness in patients following abdominal surgery.