The Sonographic Measurement of the Inferior Vena Cava Diameter versus the Central Venous Pressure in Assessing Fluid Responsiveness in Patients after Coronary Artery Bypass Graft Surgery

Background: Fluid status assessment and management post coronary artery bypass grafting (CABG) is a clinical challenge. The study aimed to establish whether central venous pressure (CVP) and ultrasound measures of respiratory variability of inferior vena cava (IVC) diameter might predict fluid responsiveness in mechanically ventilated patients after CABG. Methods: This comparative study included 200 consecutive adult patients who underwent elective CABG. We recorded the following parameters: heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), central venous pressure (CVP), inferior vena cava maximum (IVCmax), and minimum (IVCmin) diameters, left ventricular ejection fraction (LVEF), and velocity-time integral in the left ventricular outflow tract (VTI-LVOT). Results: The age of the patients ranged from 45 to 71 years, and 147 were males (73.5%). Patients were grouped into fluid responders (n= 135), defined as stroke volume variation (SVV) of 15% or greater following fluid bolus administration, and fluid non-responders (n= 65), defined SVV of less than 15% following fluid bolus administration. There was no statistically significant difference between the groups regarding their CVP, maximum and minimum IVC diameters, inferior vena cava distensibility index (IVC-DI), and other markers of fluid responsiveness (p-value 0.47, 0.34, 0.59, and 0.64, respectively). There was a significant difference in SVV between fluid responders (18.33±2.767) and non-responders (10.95±1.940) (p-value <0.001). Conclusion: Neither CVP nor sonographic measures of IVC diameter respiratory variability provided an accurate method to distinguish between fluid responders and non-responders in the early postoperative period after CABG