Contrast-enhanced Ultrasound To Evaluate Changes In Renal Cortical Microcirculation In Acute Hemorrhagic Shock:an Animal Study

BackgroundHemorrhagic shock (HS), one of a clinical acute critical illness, belongs to hypovolemic shock, which is more common in trauma. The shock syndrome which is caused by massive bleeding lead to microcirculation dysfunction, and then cause ischemia and hypoxia, thereby lead to multiple organ failure and death. To ensure the tissue perfusion flow is the key measures to successful treatment. At present, The main problem of the treatment is how to assess the organization perfusion effectively during the process. The microcirculation is the major factor reflecting tissue perfusion flow. The indicators commonly used in clinical such as blood pressure, respiration rate, sphygmus, temperature, blood lactate and blood PH can only estimate oxygenation dysfunction of the whole body. It does not reflect the microcirculation of a particular tissue or organ. It’s an urgent need to find a real-time, non-invasive, safe, and accurate method to assess the organizational microcirculation.Radionuclide imaging, CT perfusion imaging, MRI perfusion imaging and Ultrasound are all used to evaluate of renal blood perfusion. Although radionuclide imaging is the gold standard for clinical evaluation of renal perfusion function and glomerular filtration rate, but the low image resolution, long examination time and the radiation hazard clear. CT perfusion imaging is an ideal method for hemodynamic study, but the cost is more expensive, and has radiation damage. Excellent soft tissue contrast is the main advantage of MRI perfusion imaging, but the long examination time and the high magnetic field limited the application of other clinical monitoring equipment. In addition, the toxicity of the contrast agent, bulky equipment and mobile inconvenient all limited the wide use for the monitor of the microcirculation. Contrast-enhanced ultrasound (CEUS), which is real-time, non-invasive, reproducible, mobile and flexible, no significant advantage contraindications psychosis can significantly improve the organ microcirculation. Few studies have reported about the use of CEUS to evaluate the renal microcirculation of acute hemorrhagic shock, though it with high sensitivity and specificity.Part One Relationship of Doses-response to Contrast-enhanced Ultrasound with SonoVue in normal rabbit renal:an Animal StudyObjectiveThe aim of this study was to study the relationship between doses of ultrasound contrast agent SonoVue and effects of contrast-enhanced ultrasound (CEUS) in normal rabbit renal and to investigate the optimal dose of SonoVue.Materials and methodsExperimental materials1. Experimental apparatus:LOGIQ-E9 ultrasound diagnostic equipment (General Electric Company),9L-D probe.2. Others:SonoVue(Brocca, Italy),3% pentobarbital sodium, normal saline, heparin sodium, intravenous catheter.Methods1. All of ten healthy New Zealand white rabbits were anesthetized with 3% pentobarbital sodium at a dose of 0.10 ml/kg through the auricular vein, and shaved the fur of unilateral renal region. An intravenous indwelling tube (22 G) was inserted in the auricular vein.2. Ultrasound was carried out by an experienced examiner with a high resolution linear probe (6-9 MHz, LOGIQ E9, GE). SonoVue in eight different doses(0.02 ml/kg,0.04 ml/kg,0.06 ml/kg,0.08 ml/kg,0.10 ml/kg,0.12 ml/kg,0.14ml/kg, 0.16 ml/kg) was applied respectively in ten normal rabbits in randomized order with intravenous bolus injection. Corresponding parameters of the time-intensity curve (TIC):arrival time(AT), time to peak(TTP), Peak intensity(PI) and area under curve(AUC) were measured using low mechanical index(MI) true agent detection contrast mode and time intensity curve analysis software package(GE).Results1. We noted that SonoVue maintains adequate backscatter properties to show the complete process of CEUS even at low does(0.02kg/ml). Along with the increased of the SonoVue dose, the image intensity strengthened and then declined slowing.2. The TICs rose steeply and reached the peak quickly, and then declined slowing. It reflected the transition of SonoVue in region of interest (ROI).3. The TICs showed that PI and AUC increased only in the dose range from 0.02 ml/kg to 0.10 ml/kg(r=0.962、0.965, P<0.05), and PI decreased with a further increase of the SonoVue dose. AT shortened along with the increased of the SonoVue dose(r=-0.917, P<0.05). No significant correlation was found between the SonoVue dose and the TTP(r= 0.49, P<0.05).Conclusion1. The parameters of TIC are influenced intensely by different SonoVue dose. It is important to realize the relationship between the SonoVue doses and contrast-enhancement effects for microcirculatory quantification.2. The 0.10 ml/kg appears to be the optimal dose for tissue perfusion studying in healthy rabbit renal because it significantly improved video intensity and duration of enhancement and did not result in the phenomena of multiple scattering and attenuation.Part Two Relationship of Region of interest Setting to Contrast Enhanced Ultrasound(CEUS) in normal rabbit renal:an Animal StudyObjectiveThe aim of this study was to study the relationship between different sets of region of interests (ROI) and effects of contrast enhanced ultrasound (CEUS) in normal rabbit renal and to investigate the optimal sets of ROI.Materials and methodsExperimental materials1. Experimental apparatus:LOGIQ-E9 ultrasound diagnostic equipment (General Electric Company),9L-D probe.2. Others:SonoVue (Brocca, Italy),3% pentobarbital sodium, normal saline, heparin sodium, intravenous catheter.Methods1. All of twenty healthy New Zealand white rabbits were anesthetized with 3% pentobarbital sodium at a dose of 0.10 ml/kg through the auricular vein, and shaved the fur of unilateral renal region. An intravenous indwelling tube (22 G) was inserted in the auricular vein.2. Ultrasound was carried out by an experienced examiner with a high resolution linear probe (6-9 MHz, LOGIQ E9, GE). The qualitative analysis of the corresponding compartment was assessed using low mechanical index(MI) true agent detection contrast mode. Corresponding parameters of the time-intensity curve (TIC):arrival time(AT), time to peak(TTP), Peak intensity(PI) and area under curve(AUC) were measured using time intensity curve analysis software package(GE). Quantitative results of different ROIs were compared and statistically analyzed.Results1. CEUS was performed successfully in all of the rabbits. The time-intensity curves of different ROIs had a similar form.2. The corresponding parameters of the right kidney was no significantly different from that of the left kidney (P>0.05).3. As to the different set of ROIs in superficial and deep of renal cortex, significant change in PI was found (P<0.05).4. As to the different set of ROIs in cortex, medullar and hilus of rabbits’renal, significant changes in PI and AUC were found (P<0.05).5. Significant changes in AT, TTP, PI and AUC were observed between ROI in medullar and hilus of rabbits’ kidney (P<0.05).6. The set of ROI in superficial of renal cortex was better than the set of ROI in deep of renal cortex in the agreement of assessment between different observers.Conclusion:1. Different set of ROIs can affect the results of quantitative analysis. It is important to realize the relationship between the set of ROI and contrast-enhancement effects for microcirculatory quantification.2. The 3mm diameter circular ROI in cortex appears to be the optimal set of ROI for tissue perfusion studying in healthy rabbit renal.Part Three Contrast-enhanced ultrasound to evaluate changes in renal cortical microcirculation in Acute Hemorrhagic Shock:an Animal StudyObjectiveThe aim of this study was to evaluate the value of contrast-enhanced ultrasound in monitoring renal cortical microcirculation in rabbits with acute hemorrhagic shock.Materials and methodsExperimental materials1. Experimental apparatus:LOGIQ-E9 ultrasound diagnostic equipment (General Electric Company),9L-D probe. Anyview A8 modular patient monitor (Guangdong Biolight Meditech Co., Ltd.)2. Others:SonoVue (Brocca, Italy),3% pentobarbital sodium, normal saline, heparin sodium, intravenous catheter.Methods1. All of thirty healthy New Zealand white rabbits were anesthetized with 3% pentobarbital sodium at a dose of 0.10 ml/kg through the auricular vein, and shaved the fur of unilateral renal region. An intravenous indwelling tube (22 G) was inserted in the auricular vein. Another intravenous indwelling tube (22 G) was inserted in the carotid artery and connected to the tee. One end of the tee connected to the ECG monitor to measure blood pressure, and another end of the tee used as bloodletting channel.2. The experimental models of acute hemorrhagic shock were established in all of the normal New Zealand white rabbits by controlled exsanguination which were divided to four different grades:normal (100%MAP), mild (70%MAP), moderate (50%MAP) and severe (40%MAP).3. The right kidney of the experimental model was examined by Gray scale ultrasound (2DUS), CDFI and PW. The renal structures were observed by 2DUS. CDFI was used to monitor the change in renal hemodynamics associated with the progression of shock. Peak systolic velocity (Vmax), Minimum diastolic velocity (Vmin) and resistive Index (RI) of renal artery were measured by PW and compared between four different grades.4. The right kidney of the experimental model was examined by CEUS. Corresponding parameters of the time-intensity curve:AT、TTP、PI and AUC were measured by TIC analysis software package(GE, America) while the ROI was set in superficial of renal cortex. Quantitative results of different grades were compared and statistically analyzed.Results1. Thirty healthy New Zealand rabbits were successfully established the model of hemorrhagic shock. Twenty-seven healthy New Zealand rabbits were alive at the end of the experiment, and three died of severe shock.2. MAP declined, while breath and heart rate increased as the model progressed from normal to severe.3. Observation of the right renal structures by 2DUS had no obvious abnormalities between different grades.4. The TICs rose steeply and reached the peak quickly, and then declined slowing. It reflected the transition of microbubble in ROI.5. PI and AUC decreased as the hemorrhagic shock model progressed from normal to severe (P<005). AT and TTP increased as the hemorrhagic shock model progressed from mild to severe (P<0.05).ConclusionCEUS can accurately display and quantitatively assess the renal perfusion changes of acute hemorrhagic shock model of rabbits. It can be used as a noninvasive monitoring tool in the diagnosis and treatment of hemorrhagic shock. But summed up the specific reference range, a lot remains to be done further research samples.