Hemostatic Effects of Microbubble-Enhanced Low-Intensity Ultrasound in a Liver Avulsion Injury Model

<div><p>Objectives</p><p>Microbubble-enhanced therapeutic ultrasound (MEUS) can block the blood flow in the organs. The aim of this study was to evaluate the hemostatic effect of microbubble-enhanced pulsed, low-intensity ultrasound in a New Zealand White rabbit model of avulsion trauma of the liver. The therapeutic ultrasound (TUS) transducer was operated with the frequency of 1.2 MHz and an acoustic pressure of 3.4 MPa. Microbubble-(MB) enhanced ultrasound (MEUS) (n = 6) was delivered to the distal part of the liver where the avulsion was created. Livers were treated by TUS only (n = 4) or MB only (n = 4) which served as controls. Bleeding rates were measured and contrast enhanced ultrasound (CEUS) was performed to assess the hemostatic effect, and liver hemoperfusion before and after treatment. Generally, bleeding rates decreased more than 10-fold after the treatment with MEUS compared with those of the control group (P<0.05). CEUS showed significant declines in perfusion. The peak intensity value and the area under the curve also decreased after insonation compared with those of the control group (P<0.05). Histological examination showed cloudy and swollen hepatocytes, dilated hepatic sinusoids, perisinusoidal spaces with erythrocyte accumulation in small blood vessels, obvious hemorrhage around portal areas and scattered necrosis in liver tissues within the insonation area of MEUS Group. In addition, necrosis was found in liver tissue 48 h after insonation. We conclude that MEUS might provide an effective hemostatic therapy for serious organ trauma such as liver avulsion injury.</p></div

CEUS images after insonation.

<p><b>a, b</b>, Uniform perfusion of contrast agent in the MB group; <b>c, d</b>, A representative CEUS image showed a perfusion defect (arrow indicates the trauma, breakage the wound, and dotted line shows the range of defects. The area beyond the dotted line also showed an irregular defect) in MEUS group.</p

Images of procedure for application of microbubble-enhanced therapeutic ultrasound.

<p><b>a</b>’, active bleeding of the wound before insonation; <b>b</b>, Direct insonation of the wound by a transducer during injection of microbubbles; <b>c</b>, <b>c’,</b> small exudates over the wound after insonation; <b>d</b>, The liver wound were smooth and no bleeding after 48 h.</p

Representative histological HE sections after insonation of the TUS, and, MB groups.

<p>Hepatic cord and plate structure were clear, and blood cells were scattered in the sinusoids (<b>a,b</b>); In the MEUS group, hepatocytes swelled, and erythrocytes accumulated in the sinusoids (<b>c</b>), the swollen hepatocytes deformed and compressed the sinusoids and perisinusoidal space. A large number of erythrocytes accumulated in the central veins (<b>d</b>), periportal connective tissue hemorrhaged (<b>e</b>). The targets showed map-like necrosis in the MEUS group after 48 h (<b>f</b>).</p

A comparison of bleeding visual scores before and after insonation.

<p>*P<0.05 indicates a significant difference between before and after insonation of MEUS group. ⁺P<0.05 indicates a significant difference between MEUS group and the controls.</p

Correlation between bleeding rates and acoustic density analysis, bleeding visual score before and after insonation.

<p>PI means the peak intensity value, and AUC means the area under the curve.</p