Contrast-enhanced ultrasound for evaluation of renal trauma during acute hemorrhagic shock: a canine model.

Abstract

PURPOSE: Contrast-enhanced ultrasound (CEUS) is a highly specific and sensitive method for assessing hemodynamically stable patients with blunt abdominal trauma. We evaluated the efficacy of CEUS in assessing renal trauma in different states of hemodynamic instability or shock. METHODS: Hemorrhagic renal lesions reflecting grade III-IV trauma were established in the kidneys of 25 mongrel dogs. Mild, moderate, and severe systemic hypotension was induced by controlled exsanguination. The features of renal trauma in CEUS and contrast-enhanced computed tomography (CECT) were assessed and compared before shock and during shock progression. RESULTS: Gross pathology showed that with trauma, the kidneys gradually shrank and became soft, and the active bleeding in the area of the renal trauma gradually reduced and stopped. No significant differences were observed in the trauma detection rates between CEUS and CECT at any stage of shock. During the baseline and mild shock stage, sonograms obtained after intravenous injection of contrast agent showed marked contrast medium extravasation and pooling at the site of active bleeding. With shock progression, the difference in enhancement between trauma areas and the surrounding renal tissue decreased: the trauma areas became indistinct and the abnormal enhancement associated with active bleeding diminished. Further, CEUS enabled visualization of changes in renal perfusion associated with shock progression. Changes in contrast agent arrival time and the time to peaking were observed earliest in the mild shock model. The contrast agent peak intensity reduced, while the washout time increased as shock progressed from moderate to severe. CONCLUSION: In our canine model, CEUS was found to be as accurate as CECT in assessing hemorrhagic renal lesions. Thus, CEUS seems a promising tool for monitoring hemodynamic changes and predicting early shock to enable the conservative treatment of severe renal trauma.