article on echo in the crit ill (Crit Care Med 2007;35(5):s235)
Figure 2. Variation of the diameter of the inferior vena cava with respiration has recently been demonstrated to be a reliable guide to assess fluid responsiveness in patients on mechanical ventilation. Top left, ultrasonographic longitudinal view of the intrahepatic segment of the inferior vena cava (IVC) as assessed in the subcostal area. In patients on positive pressure breathing (and synchronous with the ventilator), the maximal diameter of the IVC will be obtained at the end of inspiration. Right, in such a patient, the minimal IVC diameter will be found at the end of expiration (complete collapse of the IVC is illustrated). Bottom left, precise measurement of the IVC diameter at the end-inspiratory (right arrow) and end-expiratory (left arrow) phases can be reliably obtained by using M-mode. This will allow precise assessment of the IVC diameter variation with respiration before volume loading and help identify those patients who would respond to a fluid challenge. From: Beaulieu: Crit Care Med, Volume 35(5) Suppl.May 2007.S235-S249
In general, TTE has good sensitivity for diagnosing the presence of a small, hyperdynamic left ventricle, the most typical finding in severely hypovolemic patients with underlying normal cardiac function.
| | |