Correlation of Ultrasound Guided Inferior Vena Cava Collapsibility Index with Central Venous Pressure to Assess the Volume Status in Postoperative Intensive Care Unit Patients: A Prospective Observational Study

Abstract

Background: Accurate assessment of intravascular volume status is a vital aspect of management of intensive care unit (ICU) patients. Inferior vena cava (IVC) diameter and IVC collapsibility index have surfaced as promising methods to accurately predict hypovolemia. But no such study has evaluated it’s their utility in postoperative patients.
 Methods: The study aimed to assess the correlation between ultrasound guided IVC collapsibility index (IVC CI) and CVP for volume status in intensive care unit patients. Hundred spontaneously breathing patients receiving postoperative care in our surgical ICU between November 2019 to march 2021were enrolled into the study. Maximum IVC diameter (IVCdmax) at end-expiration, minimum IVC diameter at end-inspiration (IVCdmin) and IVC CI were measured. Simultaneous CVP recordings were obtained.
 Results: A positive correlation was noted between IVC maximum diameter and CVP (p = <0.001) and between IVC Minimum Diameter and CVP. (p = <0.001) A negative correlation between IVC CI and CVP was seen (p = <0.001). Mean IVC CI was highest in the hypovolemic group. The area under the ROC curve (AUROC) for IVC CI predicting hypovolemia was 0.943 (95% CI: 0.9 - 0.986), thus demonstrating excellent diagnostic performance. At a cut off of ≥58.416%, IVC CI predicts hypovolemia with a sensitivity of 93.8%, and a specificity of 84%.
 Conclusion: IVC CI can be used to guide fluid therapy due to its excellent diagnostic accuracy in predicting hypovolemia in postoperative patients in ICU.