Hypovolemic shock evaluated by sonographic measurement of the inferior vena cava during resuscitation in trauma patients.

BACKGROUND: Inferior vena cava (IVC) diameter immediately after fluid resuscitation has not yet been investigated in trauma patients with shock on arrival.
METHODS: Between June 2004 and May 2005, 30 trauma patients with hemorrhagic shock were prospectively investigated. Using ultrasound, we measured maximum anterior-posterior diameter of the IVC just below the diaphragm in the hepatic segment, in the expiratory phase. This was performed on arrival and when systolic blood pressure had been raised to over 90 mm Hg by fluid resuscitation in the emergency room. Subjects were divided into two groups: a transient responder group (n = 17) in which shock recurred after leaving the emergency room and a responder group (n = 13) in which blood pressure remained stable.
RESULTS: There were no significant differences between the two groups regarding age or gender, or regarding vital signs or IVC diameter on arrival. Average injury severity score in the transient responder group was significantly greater than that in the responder group. After fluid resuscitation, no significant intergroup differences were observed regarding vital signs. However, IVC diameter was significantly smaller in the transient responder group than in the responder group (6.5 +/- 0.5 mm; mean +/- SE vs. 10.7 +/- 0.7 mm, p < 0.05).
CONCLUSION: In trauma patients, inadequate dilatation of the IVC by fluid resuscitation, might indicate insufficient circulating blood volume despite normalization of blood pressure. In this small study, IVC diameter appeared a better predictor of recurrence of shock than blood pressure, heart rate, or arterial base excess. A larger prospective study is called for to clearly establish the sensitivity and specificity of this method.