Diagnostic accuracy of the inferior vena cava collapsibility versus renal Doppler as predictors of fluid responsiveness in patients with sepsis

Abstract

Sepsis is a life-threatening condition characterized by an overwhelming systemic response to infection, often resulting in profound hemodynamic instability and multi-organ dysfunction. One of the critical aspects of managing sepsis is fluid resuscitation, which aims to restore effective circulating volume, improve cardiac output, and enhance tissue perfusion. To compare the diagnostic accuracy of IVC collapsibility index and renal Doppler resistive index in predicting fluid responsiveness among septic patients. This diagnostic test accuracy study conducted over a period of 9 months (from February 2025 to October 2025) in the radiodiagnosis department of a university hospital. The study population consisted of spontaneously breathing thirty septic shock patients admitted to the intensive care unit (ICU) at certain university hospital, selected based on treatment plans that include fluid resuscitation as a central component. Throughout the ICU stay, comprehensive clinical data was systematically collected to evaluate patients’ conditions and treatment progress, with the aim of assessing fluid responsiveness and refining volume resuscitation strategies to improve clinical outcomes. Approval of the ethical committee was granted, and written informed consent was obtained from all patients. Also, verbal informed consent for the publication of these data was obtained. Thirty patients were enrolled in this prospective study showed that only 56.7% of septic patients were fluid responders, confirming that fluid responsiveness is variable and cannot be predicted by demographics, comorbidities, laboratory data, or heart rate changes. Pre-fluid IVC collapsibility index and baseline IVC diameters differed significantly between responders and non-responders. The IVC collapsibility index demonstrated good diagnostic performance (AUC = 0.887), whereas the renal Doppler resistive index showed limited diagnostic performance (AUC = 0.516), though it was higher in patients with acute kidney injury. The IVC collapsibility index showed good diagnostic performance as a non-invasive predictor of fluid responsiveness in septic patients, whereas the renal Doppler resistive index showed limited diagnostic performance. These findings should be confirmed in larger prospective multicenter studies. More than half of the patients responded to fluid administration, and significant changes in IVC parameters particularly a high baseline collapsibility index were strongly associated with improved stroke volume after resuscitation.