A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine. / Bedside ultrasound of the inferior vena cava (IVC) has grown to be an important tool in the assessment and management of critically ill patients. This study endeavors to examine which location along the IVC is most highly correlated with changes in intravascular volume status: (1) the diaphragmatic juncture (DJ) (2) two centimeters caudal to the hepatic vein juncture (2HVJ) or (3) left renal vein juncture (LRVJ). Data was collected in this prospective observational study on patients in the emergency department who were at least 16 years of age, being treated with intravenous fluids (IVF). Measurements of the IVC were recorded at each site during standard inspiratory and expiratory cycles, and again with the patient actively sniffing to decrease intrapleural pressures. IVF was then administered per the patient’s predetermined treatment, and the same six measurements were repeated after completion of fluid bolus. The difference in caval index (dCI) was calculated for all six data sets and correlated with the mL/kg of IVF administered. There was a statistically significant correlation between mL/kg of IVFs administered and dCI at all three sites (DJ: r = 0.354, p value = 0.0002; 2HVJ: r = 0.334, p value = 0.0003; LRVJ: r = 0.192, p value = 0.03). The greatest correlation between amount of fluids administered and dCI was observed along the IVC at the site 2 cm caudal to the juncture of the hepatic veins (2HVJ). This site is also where the largest change in diameter can be appreciated on ultrasound during intravascular volume resuscitation. Our data also suggests that every mL/kg of IVFs administered should change the dCI by 0.86-1.00%. This anticipated change in IVC diameter can be used to gauge a patient’s response to intravascular volume repletion.

Les interactions entre coeur défaillant et organes périphériques sont centrales pour la compréhension de la variabilité de la présentation clinique, de la progression et du pronostic du syndrome insuffisance cardiaque. La congestion veineuse est considérée comme un des éléments les plus importants qui sous-tendent les interactions cardio-rénales et cardio-intestinales, faisant du retour à l’euvolémie un objectif majeur de la prise en charge du patient décompensé. De fait, la caractérisation non invasive du statut volémique permettrait d’optimiser la prise en charge en facilitant l’adaptation du traitement déplétif au cas par cas. L’objectif de ce travail est d’explorer l’effet délétère de la congestion veineuse chez le patient insuffisant cardiaque, en particulier en termes de dysfonction des organes cibles, et de répertorier l’intérêt de l’échographie multi-site pour la caractérisation du statut volémique dans cette population. / Venous congestion has been shown to play a major role in worsening renal function in acute decompensated heart failure, and recent data have challenged the assumption that end-organ dysfunction was driven by other hemodynamic alterations in patients with heart failure. Decongestion is thus considered as a major therapeutic goal in the management of patients with acute heart failure. As such, real-time assessment of patient’s fluid status may allow for a better management of patients with heart failure, enabling for a personalized management. The aim of this work is to explore the deleterious effect of venous congestion in patient with heart failure, particularly in terms of end-organ dysfunction. We also aimed to characterize the role of extra cardiac ultrasound for the assessment of the volume status in patients with heart failure.