Contrast-enhanced Ultrasound For The Characterization Of Traumatic Splenic Or Renal Bleeding In A Canine Model During Hemorrhagic Shock And Resuscitation

Objective: Contrast-enhanced ultrasound (CEUS) is a highly specific and sensitivemethod for assessment of hemodynamically stable patients with blunt abdominaltrauma. The aim of this prospective study is to assess the value of CEUS in splenicand renal trauma in dogs with haemorrhagic shock and resuscitation, for the diagnosisof rebleeding trauma after resuscitation, and also to evaluate whether the use ofultrasound contrast medium offers additional information that would evaluation ofcirculatory status, including hemodynamic monitoring, tissue perfusion measurement.Material and Methods:(1) Forty grade III-IV traumatic splenic lesions were createdin15mongrel dogs. Hemorrhagic shock was induced in these animals using themodified Wiggers’s method. Animals in shock were then resuscitated with6%hydroxyethyl starch. CEUS was performed to investigate the imaging characteristicsof splenic trauma and monitor bleeding changes continuously. Acoustic quantificationwas performed to assess splenic blood perfusion in different stage.(2) Hemorrhagic renal lesions with grade III-IV trauma were established in thekidneys of25mongrel dogs. Mild, moderate and severe systemic hypotensions wereinduced by controlled exsanguination. The features of renal trauma in CEUS andcontrast-enhanced computed tomography (CECT) were assessed and compared beforeshock and during the progression of shock.Results:(1) There was no significant difference between the detection rate of CEUSand CECT during hemorrhagic shock and resuscitation. CEUS revealed activebleeding in34(85.00%,34/40) traumatic lesions before hemorrhagic shock as eithercontrast medium extravasation or pooling, both in the spleen and outside the capsule.During the period of hemorrhagic shock, CEUS revealed that the tiny branches ofsplenic arteries decreased in number and became thinner without active bleeding. After fluid resuscitation, rebleeding occurred in30traumatic lesions, and28(93.33%)of these were captured by CEUS. CEUS could also visualize change in splenicperfusion in different stage. During the shock period, the arrival time (AT), time topeak intensity (TTP) and the washout time (WT) were significantly longer, peakintensity (PI) were significantly lower than these parameters of other stages(P<0.01).However, there were no significant differences between the blood perfusionquantitative parameter before shock and after effective fluid resuscitation (P>0.05).(2) Gross pathology showed that kidneys had gradually shrunk and become soft, andthe active bleeding in the area of renal trauma had gradually reduced and ceased.There was no significant difference between the detection rates of CEUS and CECTat any stage of shock. During the baseline and mild shock stage, sonograms obtainedafter the IV injection of contrast agent showed marked contrast medium extravasationand pooling at the site of active bleeding. With the progression of shock, thedifference in enhancement between trauma areas and the surrounding renal tissuedecreased, with the trauma areas becoming indistinct and the abnormal enhancementassociated with active bleeding diminishing. CEUS could also visualize change inrenal perfusion associated with the progression of shock. Changes in contrast agentarrival time (AT) and the time to peaking (TTP) were observed earliest in the mildshock model. The contrast agent peak intensity (PI) declined, while the wash time(WT) increased as the model progressed from moderate to severe.Conclusion: In our canine model (1) CEUS allows for real-time monitoring of splenicor renal trauma and detection of bleeding and rebleeding in hemodynamicallyunstable dogs before and after fluid resuscitation.(2) It appears that CEUS is a promising tool for the monitoring of hemodynamicchanges and to predict early shock to enable the conservative treatment of severerenal trauma.