Ultrasound Guided Measurement of Inferior Vena Cava Diameter, Common Carotid Artery Diameter versus Central Venous Pressure for Estimation of Intravascular Volume Status in Septic Shock Patients

Background: In critically ill patients, the fluid resuscitation is crucial and is the first step in treatment protocol. Invasive CVP measurement was used to guide fluid resuscitation. However, it is time consuming and invasive maneuver. Ultrasound measurement of inferior vena cave and common carotid arteries are suggest to predict the fluid response as well as CVP or even better. The current work designed to compare inferior vena cava diameter and common carotid artery diameter with central venous pressure for estimation of intravascular volume status in septic shock.    Patients and Methods: The study included 60 subjects with septic shock who received vasopressor support. CVP and ultrasound were performed before and after fluid challenge test. Values of inferior vena cava and common carotid arteries were documented and compared to CVP values.  This was performed after full clinical assessment by detailed clinical examination and laboratory workup. Results: The MAP was significantly increased and HR decreased after than before procedure.  In addition, CVP, (inferior vena cava), ICVmax, ICV min and common carotid artery diameter (CCAD) were significantly increased, IVC CI (%) was significantly reduced after procedure than basal values. There was significant decrease of IVCmax, IVCmin and CCAD while there was significant increase of IVC CI% with lower (<8) than higher (> 8) CVP values.   CVP was positively and significantly correlated with IVCmax, IVCmin and CCAD, while it was inversely correlated with IVC CI%. The AUC was over 0.75 for IVCmax, IVCmin and CCAD for prediction of CVP while it was lower than 0.7 for IVC CI%. These data reflected the better predictive power of IVCmax, IVCmin and CCAD. The best cutoff value was 1.35, 1.25, 10.45 and 4.15 for IVCmax, IVCmin, IVC CI% and CCAD successively.  Conclusion: IVC and CCA diameters measurement by US may replace CVP measurement for estimation of intravascular volume status in septic shock patients.