Comparison of Vena Cava Distensibility Index and Mini Fluid Challenge for the Evaluation of Intravascular Volume in Critically Ill Septic Shock Patient

INTRODUCTION: The assessment of volume responsiveness is of paramount importance for shock management in critical care settings as both overhydration & underhydration are deleterious. The primary goal of fluid administration is to increase cardiac output and therefore oxygen delivery by the Frank–Starling relationship, which relates stroke volume (or cardiac output) to a cardiac filling volume [1]. Excessive fluid loading can induce peripheral and pulmonary edema and compromise microvascular perfusion and oxygen delivery [2]. In the last decade, dynamic variables such as stroke volume variation, pulsed pressure variation (PPV), respiratory variation of aortic blood flow (monitored with esophageal Doppler), tidal volume challenge test, and aortic peak velocity (assessed by echocardiography); which depend on mechanical ventilation induced stroke volume variation, have been shown to be accurate in predicting fluid responsiveness [3]. Among dynamic parameters, the vena cava distensibility index (IVC - DI) have been found to predict fluid responsiveness by cut off of 12% [4]. The mini fluid challenge using crystalloid have been found to predict volume responsiveness in operation room [5]. The current prospective observational study was done to compare vena caval distensibility to mini fluid challenge using crystalloid in evaluating the volume status of critically ill patients in septic shock admitted to intensive care unit. OBJECTIVES: The current study evaluates the effectiveness of the vena cava distensibility index (IVC - DI) and mini fluid challenge (MFC) as dynamic parameters for estimating intravascular volume in critically ill patients in septic shock. MATERIALS AND METHODS: The current prospective observational study is getting conducted in Critical Care Unit, Tata Main Hospital, Jamshedpur after Scientific Research Committee and Institutional Ethics Committee clearance. Adult patients with septic shock on mechanical ventilation admitted to intensive care unit without cardiac and renal impairment will be included in the study. The vena cava distensibility index (IVC-DI) will be measured using bedside ultrasound at T 0. The mini fluid challenge will be performed by first 100 ml crystalloid over 1 min, followed by echographic assessment of subaortic Velocity time integral (VTI) and the remaining 400 ml crystalloid infusion over 14 min then echocardiographic assessment of VTI. Fluid responsiveness will be considered as an increase in the subaortic VTI ≥15% (ΔVTI(500)≥ 15%) after the infusion of 500 ml of crystalloid. Patient characteristics, Acute Physiology and Chronic Health Evaluation (APACHE) II score, Sequential organ dysfunction score, ideal body weight (kg) and ventilatory setting will be recorded at admission. These variables will be collected at baseline (T(0)), after 1 min [i.e., infusion of the first 100 ml (MFC) = T(1)], and after the end of the conventional fluid challenge (T(15)). The sensitivity and specificity of identification of fluid responsiveness by IVC - DI and MFC will be compared. RESULTS: This is an ongoing study. DISCUSSIONS: This is an ongoing study.