Objective To evaluate the effects of dexmedetomidine on the hemodynamics and the heart rate variability(HRV)in patients under-going lower limbs operations with application of tourniquet. Methods Forty patients undergoing lower limbs operations with application of tourni-quet were randomized assigned to dexmedetomidine group(group D,n=20)or control group(group C,n=20). After combined spinal-epidural anesthesia,group D received a continuous infusion of dexmedetomidine(0.5μg/kg for 10 min for loading dose and followed by 0.2μg·kg-1·h-1) until tourniquet deflation. The control group received normal saline instead. Mean arterial pressure(MAP),heart rate(HR),saturation of pulse ox-imetry(SpO2),low frequency power(LF),high frequency power(HF)and LF to HF ratio(LF/HF)were recorded at regular time points:imme-diately before loading dose(T0),before tourniquet inflation(T1),15 min after tourniquet inflation(T2),30 min after tourniquet inflation(T3),45 min after tourniquet inflation(T4),60 min after tourniquet inflation(T5),1 min after tourniquet deflation(T6),5 min after tourniquet deflation (T7)and 10 min after tourniquet deflation(T8). Results Compared with T0,the MAP of group D significantly decreased at T6-T8(P<0.05). Compared with T0 and T1,the MAP of group C increased at T2-T5(P>0.05). Compared with T2-T5,the MAP of group C significantly decreased at T6(P<0.05). Compared with group C,the MAP of group D significantly decreased at T6 and T7(P<0.05). Compared with T0,the HR of group D significantly decreased at T1-T8(P<0.05). Compared with T0,the HR of group C had no significant change at T1-T5(P<0.05). Compared with T1-T5,the HR of group D and group C significantly increased at T6(P<0.05). Compared with group C,the HR of group D significantly decreased at T1-T4 and T6(P<0.05). Compared with T0,the SpO2 of group D and group C significantly decreased at T6(P<0.05). Compared with group C,the SpO2 of group D significantly decreased at T1-T3(P<0.05). Compared with T6,LF of group D and group C significantly increased at T7(P<0.05). LF were comparable between groups D and C(P>0.05). Compared with T0,the HF of group D significantly increased and the LF/HF of group D significantly decreased at T1-T4(P<0.05). Compared with group C,the HF of group D significantly increased and the LF/HF of group D significantly decreased at T1-T4(P<0.05). Conclusion The appropriate dose of dexmedetomidine(loading dose 0.5μg/kg and maintenance dose 0.2μg · kg-1 · h-1)can significantly increase vagal tone and improve cardiac sympathetic and parasympathetic balance during tourniquet appli-cation.

Objective: To evaluate the characteristics of renal cortical blood perfusion assessed by contrast-enhanced ultrasound (CEUS) in elderly patients with renal artery stenosis (RAS) and its relationship with renal function. Methods: Ninety-three elderly patients diagnosed with RAS, who were admitted in Beijing Hospital during June 2017 and December 2018, were retrospectively enrolled. According to the degree of RAS, 186 renal arteries were divided into normal renal artery group (n=79), mild RAS group (30% to 49%, n=59), moderate RAS group (50% to 70%, n=33), and severe RAS group (70% to 99%, n=15). Renal cortical blood perfusion and renal glomerular filtration rate (GFR) were measured by CEUS and radionuclide renal dynamic imaging. According to the renal GFR, 186 kidneys were divided into normal renal function group (GFR≥35 ml/min, n=42) and mild renal insufficiency group (35 ml/min>GFR≥25 ml/min, n=51), moderate renal insufficiency group (25 ml/min>GFR≥15 ml/min, n=75) and severe renal insufficiency group (GFR<15 ml/min, n=18). The renal cortical blood perfusion time-intensity curve (TIC) and related parameters were analyzed, including the area under the curve (AUC), the slope of the ascending branch (A), the peak intensity (PI), the peak time (TTP) and the mean transit time (MTT), the kidneys of different RAS groups and patients with different renal function groups were analyzed. Pearson correlation analysis was used to evaluate the correlation between renal cortical blood perfusion parameters and renal GFR. Results: (1) Renal cortical blood perfusion and GFR: CEUS showed that parameter A of TIC was significantly reduced, while TTP was prolonged in the mild renal artery stenosis group compared with the normal renal artery group (both P<0.05), GFP was similar between the two groups. Cortical perfusion parameters, such as AUC, A, PI and GFR were significantly lower, while TTP and MTT were significantly prolonged in the moderate and severe renal artery stenosis group than in the normal and mild stenosis groups (all P<0.05). Compared with the moderate stenosis group, AUC, A, PI and GFR were significantly lower while TTP, MTT were significantly prolonged in the severe renal artery stenosis group (all P<0.05). (2) TIC showed that the renal perfusion parameters, AUC, PI and A were significantly lower, while TTP was significantly longer in the mild renal dysfunction group than in the normal renal function group (all P<0.001). The changes aggravated in proportion with renal dysfunction. (3) Correlation between perfusion parameters and GFR: Pearson correlation analysis showed that the AUC (r=0.774, P<0.05), A (r=0.815, P<0.05) and PI (r=0.772, P<0.05) were positively correlated with GFR; serum creatinine level (r=-0.841, P<0.05), renal function grading (r=-0.731, P<0.05), TTP (r=-0.803, P<0.05) and MTT (r=-0.741, P<0.05) were negative correlated with GFR. The degree of stenosis was negatively correlated with GFR (r=-0.427, P<0.05). Conclusion Cortical perfusion parameters differ significantly among patients with various degree of RAS and renal dysfunction. The renal cortical blood perfusion parameters are correlated with renal GFR.

Objective To investigate the renal cortical perfusion parameters assessed by contrast-enhanced ultrasound(CEUS)in elderly patients with moderate-to severe renal artery stenosis (RAS),and relationship of those with glomerular filtration rate(GFR).Methods A total of 59 elderly patients with unilateral moderate to severe RAS(50％-99％)admitted into Beijing Hospital during June 2017 to December 2018 were consecutively enrolled in the cross sectional and self-control study.Based on the GFR assessed by radionuclide renal dynamic imaging,patients were divided into the mild-(35＞GFR≥25 ml/min,n=18),moderate-(25 ＞ GFR≥ 15 ml/min,n =37) and severe renal dysfunction(GFR＜ 15 ml · min-1,n =4) groups.CEUS evaluated-renal cortical perfusion parameters,including area under curve (AUC),ascending slope (A),derived peak intensity (DPI),time to peak (TTP) and mean transit time(MTT),were compared among different levels of severity of renal dysfunction groups.Pearson correlation analysis was used to evaluate the relationship between CEUS imaging-evaluated renal cortical perfusion parameters and radionuclide renal dynamic imaging-assessed GFR.Results Compared with the mild renal dysfunction group,the moderate renal dysfunction group showed a reduced AUC and A(P＜0.05),and the severe renal dysfunction group showed more markedly reduced AUC,A,DPI,TTP and MTT (P ＜ 0.05).Compared with the moderate renal dysfunction group,the severe renal dysfunction group showed a reduced AUC,A and GFR(P ＜0.05),while no significant differences in TTP and MTT were found.As far as relationship between renal cortical perfusion parameters and GFR were concerned,Pearson correlation analysis demonstrated that AUC(r =0.804),A(r =0.813) and DPI(r =0.733) were significantly and positively correlated with GFR(all P ＜ 0.05).However,renal function (r =-0.721),TTP(r =-0.744) and MTT(r =-0.743)were negatively correlated with GFR(P＜0.05).And the degree of renal artery stenosis was poorly correlated with GFR (r =-0.462).Conclusions For elderly patients with unilateral moderate to severe RAS,contrast-enhanced ultrasonography can display the changes of renal cortical blood perfusion parameters along with the aggravation of renal function impairment.AUC and A are strongly positively correlated with GFR.The degree of renal artery stenosis is poorly correlated with renal function.And more studies are needed to confirm these findings.

Objective To explore the characteristics of renal cortical perfusion with contrastenhanced ultrasound (CEU)in elderly mice.Methods Randomly selected 12 healthy C57BL/6J young mice(aged 1-2 months)and 12 healthy elderly mice(aged 18-20 months)were assigned respectively into the control group and the experimental group.All mice were examined by color Doppler ultrasound and CEU.Renal morphology and hemodynamics were assessed with conventional ultrasound and CEU was used to assess renal microvascular perfusion,analyzing the time-intensity curve(TIC) and related parameters,including slope rate of ascending curve (A),area under curve (AUC),peak intensity (PI),and time to peak (TTP).Results Conventional ultrasound showed similar blood flow dynamics in the renal hilum artery,the renal segmental artery and the renal interlobar artery between the young and elderly mice groups(all P ＞0.05).Moreover,CEU showed slower ascendance of TIC in the elderly mice group(P ＜ 0.05).Furthermore,the elderly mice were associated with significantly decreased A (0.74 ± 0.06 vs.0.89 ± 0.12,P ＜ 0.05) and increased AUC (1420.08± 208.30)dB · s vs.(1261.41± 34.65)dB/s(P＜0.05),delayed TTP(7.75 ±0.88)s vs.(6.93± 0.44) s (P ＜ 0.05),and similar PI (P ＞ 0.05),compared with those in the young mice group.Conclusions Qualitative analysis of CEU is capable of detecting renal perfusion differences between young and elderly nice,which might lay a basis for further study.

Objective To investigate the clinical value of contrast-enhanced ultrasonography (CEUS)in evaluating renal cortical perfusion in elderly diabetic patients.Methods A retrospective cross-sectional study was conducted.A total of 70 diabetic patients with chronic renal insufficiency stage 1 to 5 were enrolled.The glomerular filtration rate (GFR)was estimated according to the creatinine level.Based on GFR,patients were divided into a mild-to-moderate chronic kidney disease (CKD)group(n=42,CKD stage 1 to 3)and a severe CKD group(n=28,CKD stage 4 to 5).All patients underwent CEUS for the assessment of renal perfusion and renal dynamic imaging for the assessment of GFR.QLAB analysis software was used to obtain the time-intensity curve(TIC)and related parameters including area under the curve(AUC),the ascending slope(A),the derived peak intensity(DP1) and the time to peak (TTP).The differences in renal perfusion parameters were compared between the two groups.Pearson correlation test was used to assess the correlation between the quantitative parameters of renal cortical perfusion and GFR.Results There was no significant difference in age,gender,history of hypertension,basal blood glucose level,systolic or diastolic blood pressure between the two groups (all P ＞ 0.05).CEUS findings revealed high renal cortical blood perfusion in the mild-to-moderate group.There were significant differences in quantitative perfusion parameters including AUC,DPI,A and TTP between the two groups.Pearson correlation test indicated that TTP and A were significantly correlated with GFR in both groups(r =-0.456 and-0.693,0.432 and-0.529,all P＜0.05),while AUC and DPI had no correlation with GFR(r =-0.003 and -0.057,0.066 and-0.081,all P ＞0.05).Conclusions Diabetic patients with mild-to-moderate CKD have high renal cortical blood perfusion.CEUS findings can indirectly reflect renal function.The perfusion parameters A and TTP have good correlations with GFR.CEUS can be used as a safe and effective method to evaluate renal function,especially in patients with severe renal insufficiency,but more studies are needed to verify the results.

Objective:To observe the effect of the cortical blood perfusion parameter of wash-in area under curve (iAUC) with contrast-enhanced ultrasound(CEUS) on the effect of short-term outcomes of stent implantation in patients with severe renal artery stenosis (RAS).Methods:Retrospective analysis was performed on 82 patients with unilateral severe RAS who received stent implantation in Beijing Hospital from October 2017 to December 2019. According to the baseline iAUC before CEUS, all patients were divided into the poorly-perfused group (iAUC<850.0 dB×s) (37 cases) and the well-perfused group (iAUC≥850.0 dB×s) (45 cases). Baseline and perioperative clinical-imaging data were analyzed between the two groups. Followed up for 10-12 (11.5±1.7) months, Kaplan-Meier survival curves and Log-rank test were used to analyze the rate of adverse cardiac and renal vascular events and hypertension control rates.Results:Compared with the well-perfused group, the poorly-perfused group showed a longer course of hypertension, more diabetic patients, higher systolic blood pressure, diastolic blood pressure, 24 h average systolic blood pressure, and 24 h average diastolic blood pressure, lower glomerular filtration rate, and severe renal artery stenosis. Besides, the iAUC, wash-out AUC and the peak intensity were lower, the average transit time was longer, and the hypoglycemic treatment rate was higher (all P<0.05). Kaplan-Meier survival curve and Log-rank test analysis showed that the occurrence of cardio-renal vascular events ( HR=0.361, 95% CI=0.144-0.907, P=0.012) and renal function deterioration rate ( HR=0.286, 95% CI=0.090-0.914, P=0.035) in the well-perfused group were significantly lower than those in the poorly-perfused group. The blood pressure results demonstrated that the effective rate of hypertension treatment in the well-perfused group was significantly higher than that in the poorly-perfused group (93.3% vs 59.5%, P<0.001), but the improvement rate of hypertension (60.0% vs 43.2%) and cure rate (28.9% vs 16.2%) were not statistically significant between the two groups(all P>0.05). Conclusions:Severe RAS patients with decreased baseline iAUC often have diabetes, longer duration of hypertension, significantly reduced glomerular filtration rate and more severe RAS, short-term outcomes are worse with stent implantation.

Objective To explore the clinical value of the contrast-enhanced ultrasound (CEUS) in the diagnosis of renal artery stenosis(RAS).Methods A total of 20 patients(12 males and 8 females) including 40 renal arteries,who were suspected to have RAS were enrolled in Department of Renal,Beijing Hospital.All patients were examined by color doppler ultrasound,CEUS and digital subtraction angiography (DSA).The results of conventional ultrasound and CEUS were compared with the DSA results,respectively.Results All patients had history of hypertension,aged (65 ± 5)years.12 branches (mild 6,moderate 4,severe 2) were RAS by regular ultrasound,17 branches (mild 8,moderate 6,severe 3)were RAS by by CEUS,while 19 branches (mild 9,moderate 7,severe 3) were diagnosed as RAS by DSA.The measure of agreement Kappa between conventional ultrasound and DSA was lower than that between CEUS and DSA (0.77 vs.0.96,P＜0.01).The diagnostic accuracy of mild,moderate and sever RAS with CEUS were 88.9％,94.1％ and 100％,respectively.Conclusions CEUS shows the renal artery more clearly than conventional ultrasound,and has a high consistency with DSA in the diagnosis of RAS.

Objective:To establish and validate a prognostic model of a contrast-enhanced ultrasound scoring(CEUS)system for evaluating renal artery stenosis(RAS)in the elderly.Methods:This was a single-center retrospective study.A total of 324 elderly RAS patients admitted to Beijing Hospital from October 2017 to July 2020 were randomly assigned into the model group(n=174)and the validation group(150)in a 1∶1 ratio.Clinical and imaging data of patients on admission including general conditions, previous medical history, blood pressure, blood creatinine, renal artery stenosis and cortical blood perfusion in the affected kidney and renal function(GFR)at 1-year follow-up were collected.Univariate and multivariate logistic regression was used to establish a model of the CEUS scoring system.The receiver operating characteristic(ROC)curve and area under the ROC curve(AUC)were used to evaluate prediction accuracy.Clinical application value of the CEUS scoring system model was evaluated via decision curve analysis using a nomogram.Results:Baseline clinical and radiomic data had no significant difference between the model group and the validation group( P>0.05). Multivariate logistic regression analysis results showed that age( OR=1.242, 95% CI: 1.081-1.427, P<0.01), diabetes( OR=1.545, 95% CI: 1.107-2.156, P<0.05), blood pressure( OR=1.328, 95% CI: 1.056-1.670, P<0.05), renal function( OR=2.374, 95% CI: 1.216-3.887, P<0.01)and cortical blood perfusion parameter( OR=2.646, 95% CI: 1.553-6.369, P<0.01)were risk factors for the deterioration of renal function during 1 year follow-up.Based on these results, a nomogram for the CEUS scoring system model was drawn, and its consistency index, the C-Index, was 0.725(95% CI: 0.653-0.776). The AUC of the CEUS scoring system was 0.824 and the Youden index was 0.711 in the model group, with a specificity of 0.774 and a sensitivity of 0.837.The AUC of the CEUS scoring system was 0.853 and the Youden index was 0.715 in the validation group, with a specificity of 0.684 and a sensitivity of 0.889.There was no significant difference in ROC curve between the two groups( D=1.387, P>0.05). In addition, calibration charts of the two models showed that the calibration curve of the CEUS scoring system was close to the standard curve, with no statistically significant difference( P>0.05). Conclusions:The CEUS scoring system model can be used to predict the risk of worsening renal function in elderly RAS patients during 1-year follow-up.

Objective:To investigate the imaging characteristics on contrast-enhanced ultrasound(CEUS)of carotid plaque instability and their correlation with histopathological changes in elderly patients.Methods:Twenty-three patients undergone carotid endarterectomy(CEA)at the Department of Neurosurgery of Beijing Hospital from June 2018 to November 2020 were retrospectively enrolled, including 27 males and 5 females, aging from 60 to 87(68.1±6.3)years.They were diagnosed with moderate to severe carotid artery stenosis(50%-99%)based on digital subtraction angiography(DSA).Carotid artery CEUS was conducted before surgery, and HE staining and CD34 immunohistochemical staining were used to record histopathological scores and microvessel density(MVD)counts.Results:The mean pathological score and MVD count were 2.46±0.66 and 37.17±12.88 for 32 cases with hypoechoic patterns, 22.42±0.55 and 38.06±13.66 for 18 cases with mixed echo patterns, and 2.75±0.35 and 23.50±9.192 for 2 cases with strong echo patterns, respectively.CEUS grading was positively correlated with histopathology score and MVD count( r=0.53、0.76, all P<0.01). Conclusions:Low echo and mixed echo plaques are more unstable than strong echo plaques.CEUS can be used to comprehensively assess the vulnerability of atherosclerotic plaques and to decide the optimal surgical time for patients with carotid atherosclerotic plaque stenosis.