体外冲击波碎石焦点区域声压分布的时域有限差分法仿真研究

目的:研究体外冲击波碎石(Extracorporeal shock wave lithotropisy,ESWL)治疗中不同厚度人体组织对ESWL焦点区域大小、位置和声压分布的影响,为ESWL治疗计划的制定提供理论依据.方法:以Reichenberger的ESWL水中实验为参照例,分别建立三维单一人体组织和多层复合人体组织仿真模型,用时域有限差分(Finite Difference Time Domain,FDTD)数值仿真法,数值仿真ESWL治疗中形成的焦点区域.结果:高强度聚焦超声波在人体脂肪、肌肉层中形成的实际焦点区域大小、位置和焦点区域声压分布随着人体脂肪、肌肉层厚度的变化而变化.结论:ESWL治疗过程中由于人体组织厚度的不同,高强度聚焦超声非线性传播而形成的焦距和最大声压不同,对于不同体态的患者在ESWL治疗时,应该采用不同的焦距设定方法.     

体外冲击波碎石术后并发症的防治进展

体外冲击波碎石术(extracorporeal shock wave lithotripsy,ESWL)是利用航天技术空化效应的原理,从体外把体内的结石冲击粉碎,使之随尿液排出体外的一种技术,是治疗泌尿系结石的首选方法[1].但冲击波对人体组织器官可产生一定的影响,造成一定的损伤,可发生各种并发症.因此,防治ESWL术后并发症,对提高ESWL的治疗效果和安全性至关重要.作者就近年来ESWL术后出现的石街、出血、发热、肾绞痛及肾功能改变等并发症的防治进展概述如下.     

净石灵胶囊联合体外冲击波碎石术治疗复杂性肾结石临床疗效分析

目的:探讨净石灵胶囊联合体外冲击波碎石术治疗复杂性肾结石临床疗效。方法:选取2010年1月-2011年12月在我院就诊的复杂性肾结石患者83例,随机分为体外冲击波碎石术组、经皮肾镜碎石取石组、净石灵胶囊联合体外冲击波碎石术组。观察两组间的手术时间、碎石率、疗效以及组内之间不同直径的结石的碎石率。结果:ESWL组碎石成功率85.3%,PCNL组碎石成功率90.0%,净石灵胶囊联合体外冲击波碎石术组碎石成功率89.7%,三组比较无统计学意义(P>0.05);ESWL组手术时间(40.2±6.3)min,PCNL组手术时间(46.6±4.1)min,净石灵胶囊联合体外冲击波碎石术组手术时间(42.2±5.7)min,三组比较无统计学意义(P>0.05);ESWL组、PCNL组、净石灵胶囊联合体外冲击波碎石术组治疗复杂性肾结石的有效率依次为75.0%、80.0%、97.4%,组间比较,差异具有统计学意义(P<0.05);ESWL组5<10mm、10<15mm、15<20mm直径的肾结石的粉碎率依为100%、85.7%、40%,组内比较具有统计学意义(P<0.01),PCNL组5<10mm、10<15mm、15<20mm直径的肾结石的粉碎率依次为100%、83.3%、75%,组内比较具有统计学意义(P<0.05),净石灵胶囊联合体外冲击波碎石术组5<10mm、10<15mm、15<20mm直径的肾结石的粉碎率依次为100%、88.9%、57.1%,组内比较具有统计学意义(P<0.01)。结论:体净石灵胶囊联合体外冲击波碎石术治疗复杂性肾结石的临床疗效优于单纯运用体外冲击波碎石术或经皮肾镜碎石取石术。     

体外冲击波碎石术的临床应用

由于体外冲击波碎石(extracorporeal shock wave lithotripsy,ESWL)的治疗过程基本上属于非侵入性的,且成功率高,因此在临床实践中得到广泛的应用。我院自1988年至2003年应用该技术治疗泌尿系结石已逾5000例,兹将临床应用中的一些经验及对该技术的影像学要求报导于下。     

坦洛新对输尿管下段结石患者体外冲击波碎石术后排石及血清IL-6，IL-10和CRP水平的影响

目的:探讨输尿管下段结石行体外冲击波碎石术(ESWL)后应用坦洛新辅助排石的临床效果及对患者血清白细胞介素-6(IL-6)、白细胞介素-10(IL-10)、C反应蛋白(CRP)水平的影响。方法:选取我院2015年1月～2016年12月收治的122例输尿管下段结石患者,采用随机数字表法均分为两组。于ESWL术后,对照组给予硝苯地平治疗,观察组予以坦洛新治疗。记录比较两组术后排石效果、疼痛情况,治疗前后血清IL-6、IL-10和CRP水平的变化及不良反应的发生情况。结果:治疗后,观察组无石率(91.8%)明显高于对照组(78.7%)(P0.05);观察组排石时间短于对照组,排石直径大于对照组(P0.05);观察组患者血清IL-6,IL-10及CRP水平均显著低于对照组(P0.05)。与对照组相比,观察组肾绞痛发生率、镇痛剂使用率及VAS评分均较低(P0.01)。用药期间,两组均未发生明显不良反应(P0.05)。结论:坦洛新能有效提高输尿管下段结石患者体外冲击波碎石术的排石效果,减轻机体损伤,缓解术后疼痛,并且安全性较高。     

体外冲击波碎石术对兔肝酶活性的影响

采用超微组织化学方法,观察了体外冲击波碎石术(ESWL)对家免肝脏酶活性的影响。实施 ESWL 后,肝细胞的琥珀酸脱氢酶(SDH)和毛细胆管壁上的碱性磷酸酶(ALP)、焦磷酸硫胺素酶(TPPase)反应活性减弱或消失。TPPase 从损伤的肝细胞高尔基体分泌面扁囊、溶酶体样小泡和毛细胆管内溢出,并伴有肝细胞面的质膜上出现了 TPPase 反应产物和形成膜包内凹小泡。结果提示 ESWL 可对肝细胞及毛细胆管的功能和结构有损伤作用。     

浅谈体外冲击波碎石术在泌尿系结石中的应用

目的:探讨体外冲击波碎石术在泌尿系结石中的临床疗效。方法:选取泌尿系结石患者共3100例,均采取惠康HA-108A型体外冲击波碎石机进行治疗。结果:3100例病人体外冲击波碎石术过程均顺利,术后15天超声复查,2870例病人结石已随尿液排出,占92.58%,余230例病人结石已粉碎,未排出。结论:随着体外冲击波碎石术的广泛应用及治疗经验的积累,对于泌尿系结石的清除是非侵入性、无痛苦的治疗技术,它既能粉碎结石,又不会对人体造成不可逆的损伤,所以是一种对人体安全的非常有效的治疗手段,准确的定位是碎石的根本保证。只要正确掌握体外冲击波碎石术和碎石机的碎石技巧,完全可以达到效果好、痛苦少、费用低、安全有效的目的。     

体外冲击波碎石机及其应用

体外冲击波碎石术〈ESWL〉是本世纪80年代的高科技技术。1980年2月首先在德国由Chaussy等治疗肾结石取得良好效果。1983年后由德国Dornier公司相继制造出HM_3、HM_4、MFL5000及MPL9000等类型的碎石机,在世界各国广泛用于临床,适应症扩展到输尿管结石,近年又成功地用于胆结石。1985年后法国、美国、以色列,我国的北京、上海、汕头、西安也制造出了类似的碎石机。ESWL揭开了物理医学新的一页,是尿石     

输尿管镜下钬激光碎石与体外冲击波碎石术治疗输尿管结石的比较研究

目的:研究输尿管镜下钬激光碎石与体外冲击波碎石术治疗输尿管结石的效果。方法:选取2013年1月到2015年1月我院收治的输尿管结石患者100例,根据手术方法不同将患者分为A组(n=56例,直径≥1 cm者23例,直径1 cm者33例)和B组(n=44例,直径≥1 cm者17例,直径1 cm者27例),其中A组给予输尿管镜下钬激光碎石治疗,B组给予体外冲击波碎石术治疗,比较两组手术时间、结石排净、术后并发症。结果:A组直径≥1 cm和1 cm者手术时间为(55.9±1.6)min和(38.9±0.7)min显著低于B组的(72.8±1.4)min和(53.6±0.7)min(P0.05);A组直径≥1 cm者结石排净率为87%显著高于B组的58.8%(P0.05),A组直径1 cm者90.9%与B组88.9%相近(P0.05);两组并发症发生率比较差异无统计学意义(P0.05)。结论:输尿管镜下钬激光碎石相比体外冲击波碎石术治疗输尿管结石手术时间短,对于直径≥1 cm者效果较好。     

排石汤联合盐酸坦洛新辅助体外冲击波碎石术治疗上尿路结石的临床疗效分析

目的:探讨排石汤联合盐酸坦洛新辅助体外冲击波碎石术(ESWL)治疗上尿路结石的临床疗效。方法:选择我院2015年1月~2016年9月收治的120例上尿路结石患者,采取随机数字表将其分成两组,每组60例。两组患者均行ESWL治疗,并于术后辅助使用盐酸坦洛新,观察组在上述治疗基础上联合排石汤治疗,对比两组的临床疗效以及治疗前后血清肌酐(Scr)、中性粒细胞明胶酶相关载脂蛋白(NGAL)、半胱氨酸蛋白酶抑制剂C(Cys-C)、肾小球滤过率(GFR)水平的变化情况。结果:观察组总有效率为96.60%,对照组为86.67%,观察组总有效率明显高于对照组(P0.05)。观察组结石排净率为95.00%,明显高于对照组(P0.05);肾绞痛发生率为6.67%,明显低于对照组(P0.05),结石排出时间、血尿持续时间均显著短于对照组(P0.01)。两组1年复发率对比差异无统计学意义(P0.05)。两组患者术后2 h、1 d血清NGAL、Cys-C水平逐渐升高,GFR逐渐下降,术后3 d上述指标逐渐恢复。观察组术后1 d、3 d NGAL、Cys-C水平明显低于对照组,GFR明显高于对照组(P0.01)。两组术前术后各时点Scr比较差异均无明显统计学意义(P0.05)。结论:排石汤联合盐酸坦洛新辅助ESWL治疗上尿路结石的临床疗效显著,并可有效改善ESWL引起的肾损伤。     

Focusing water shock waves for lithotripsy by various ellipsoid reflectors

A spherical shock wave generated in the first focus of an ellipsoid is focused in the second focus after reflection. Shadowgraphs provide an impression of the converging process, while the pressure field ist measured with speciality designed pressure probes having a high temporal and spatial resolution. Two different types of reflectors have been investigated. The first is like a spherical mirror with a short focal length, the second is a deep reflector "surrounding" the generation point. Variation of the parameters, size of the reflector, and incident shock energy reveal their influence on the focusing process and the point of maximal pressure, which in the case of deep ellipsoids can deviate from the geometrical focus. Here, non-linear propagation effects on the long distances to the focus lead to an increase in the size of the focal region. Although these reflectors utilize much more of the primary shock front, their peak pressure of 400 bar is low compared with the "shallow" reflectors with 1200 bar and their small focus. The effect of the deep type on kidney stones is however greater. The desintegration process and the reaction of the generated cavitation bubbles have been studied with a high speed camera. It can be shown that stone splinters do not injure the kidney tissue, but liquid jets generated by oscillating cavitation bubbles lead to tissue damage.     

The Dornier lithotripter in a comparison. Measuring shockwave fields and fragmentation effects

For all Dornier lithotripters, comparative shock wave field measurements performed by using a modern piezoelectric pvdf-shock wave measuring technique. The high temporal and spatial resolution of the pressure probe provides many details of the focusing field right up to the focal point. The maximum amplitudes, the axial and lateral pressure distribution around the focus, and their changes as a function of primary energy are presented. Focusing is influenced in particular by the geometry of the reflector, diffraction- and non-linear propagation effects. A comparison between incident shock energies on model calculi in vitro and the resulting fragmentation shows the relationship between focus energy and disintegration effect. For a given lithotripter with fixed electrical and geometrical parameters, the number of shocks needed for complete fragmentation of the model calculus is inversely proportional to the square of the capacitor voltage, and proportional to the volume of the model calculus.     

Effects of Shock Waves on Oxidative Stress, Antioxidant Enzyme and Element Levels in Kidney of Rats

The aim of this study was to investigate the effect of extracorporeal shock wave lithotripsy (ESWL) on kidney oxidative stress and trace element levels of adult rats. Twelve male Wistar albino rats were divided equally into two groups. First group was used as control. The right-side kidneys of animals in second group were treated with 2,000 18-kV shock waves under anesthesia. Localization of the right kidney was achieved following contrast medium injection through a tail vein under flouroscopy control. The animals were sacrificed 72?h after the ESWL treatment, and the kidneys were taken. Malondialdehyde level was higher in the ESWL group than in the control. Reduced glutathione levels, superoxide dismutase, and glutathione peroxidase activities were lower in the ESWL group than those of the control. Fe, Cu, Pb, Mn, Cd, and Ni levels were lower in the ESWL group than in the control, although Mg level was higher in the ESWL group than in the control. In conclusion, the result of the present study indicated that ESWL treatment produced oxidative stress in the kidney and caused impairments on the antioxidant and trace element levels in the kidneys of rats.     

Pressure wave propagation in fluid-filled co-axial elastic tubes. Part 1: Basic theory

Our work is motivated by ideas about the pathogenesis of syringomyelia. This is a serious disease characterized by the appearance of longitudinal cavities within the spinal cord. Its causes are unknown, but pressure propagation is probably implicated. We have developed an inviscid theory for the propagation of pressure waves in co-axial, fluid-filled, elastic tubes. This is intended as a simple model of the intraspinal cerebrospinal-fluid system. Our approach is based on the classic theory for the propagation of longitudinal waves in single, fluid-filled, elastic tubes. We show that for small-amplitude waves the governing equations reduce to the classic wave equation. The wave speed is found to be a strong function of the ratio of the tubes' cross-sectional areas. It is found that the leading edge of a transmural pressure pulse tends to generate compressive waves with converging wave fronts. Consequently, the leading edge of the pressure pulse steepens to form a shock-like elastic jump. A weakly nonlinear theory is developed for such an elastic jump.     

Numerical study of the effect of ultrasound frequency on temperature distribution in layered tissue

The high intensity focused ultrasound (HIFU) technology can produce therapeutic benefits in deep-seated tissues of interest, selectively and noninvasively. In order to control the treatment process, it is important to recognize the heat generation in biological tissue and the parameters that have an effect on temperature rising. This study investigates the influence of frequency and source intensity on temperature distribution during high-intensity focused ultrasound (HIFU). A nonlinear full wave equation model is simulated to compute the pressure field. Additionally, the absorbed coefficient of tissue is added to the nonlinear equations to simulate accurately the wave propagation in tissue with high absorbed coefficient. In addition, temperature distribution was solved by the Pennes bio-heat equation. Conclusively, frequencies in the range of 1–1.5 MHz are prescribed to have maximum heat absorption in the focal region.     

One-dimensional model for propagation of a pressure wave in a model of the human arterial network: comparison of theoretical and experimental results

Pulse wave evaluation is an effective method for arteriosclerosis screening. In a previous study, we verified that pulse waveforms change markedly due to arterial stiffness. However, a pulse wave consists of two components, the incident wave and multireflected waves. Clarification of the complicated propagation of these waves is necessary to gain an understanding of the nature of pulse waves in vivo. In this study, we built a one-dimensional theoretical model of a pressure wave propagating in a flexible tube. To evaluate the applicability of the model, we compared theoretical estimations with measured data obtained from basic tube models and a simple arterial model. We constructed different viscoelastic tube set-ups: two straight tubes; one tube connected to two tubes of different elasticity; a single bifurcation tube; and a simple arterial network with four bifurcations. Soft polyurethane tubes were used and the configuration was based on a realistic human arterial network. The tensile modulus of the material was similar to the elasticity of arteries. A pulsatile flow with ejection time 0.3 s was applied using a controlled pump. Inner pressure waves and flow velocity were then measured using a pressure sensor and an ultrasonic diagnostic system. We formulated a 1D model derived from the Navier-Stokes equations and a continuity equation to characterize pressure propagation in flexible tubes. The theoretical model includes nonlinearity and attenuation terms due to the tube wall, and flow viscosity derived from a steady Hagen-Poiseuille profile. Under the same configuration as for experiments, the governing equations were computed using the MacCormack scheme. The theoretical pressure waves for each case showed a good fit to the experimental waves. The square sum of residuals (difference between theoretical and experimental wave-forms) for each case was <10.0%. A possible explanation for the increase in the square sum of residuals is the approximation error for flow viscosity. However, the comparatively small values prove the validity of the approach and indicate the usefulness of the model for understanding pressure propagation in the human arterial network.     

Theoretical analysis of pressure pulse propagation in arterial vessels.

An original mathematical model of viscous fluid motion in a tapered and distensible tube is presented. The model equations are deduced by assuming a two-dimensional flow and taking into account the nonlinear terms in the fluid motion equations, as well as the nonlinear deformation of the tube wall. One distinctive feature of the model is the formal integration with respect to the radial coordinate of the Navier-Stokes equations by power series expansion. The consequent computational frame allows an easy, accurate evaluation of the effects produced by changing the values of all physical and geometrical tube parameters. The model is employed to study the propagation along an arterial vessel of a pressure pulse produced by a single flow pulse applied at the proximal vessel extremity. In particular, the effects of the natural taper angle of the arterial wall on pulse propagation are investigated. The simulation results show that tapering considerably influences wave attenuation but not wave velocity. The substantially different behavior of pulse propagation, depending upon whether it travels towards the distal extremity or in the opposite direction, is observed: natural tapering causes a continuous increase in the pulse amplitude as it moves towards the distal extremity; on the contrary, the reflected pulse, running in the opposite direction, is greatly damped. For a vessel with physical and geometrical properties similar to those of a canine femoral artery and 0.1 degree taper angle, the forward amplification is about 0.9 m-1 and the backward attenuation is 1.4 m-1, so that the overall tapering effect gives a remarkably damped pressure response. For a natural taper angle of 0.14 degrees the perturbation is almost extinct when the pulse wave returns to the proximal extremity.     

Cytoplasmic molecular delivery with shock waves: importance of impulse

Cell permeabilization using shock waves may be a way of introducing macromolecules and small polar molecules into the cytoplasm, and may have applications in gene therapy and anticancer drug delivery. The pressure profile of a shock wave indicates its energy content, and shock-wave propagation in tissue is associated with cellular displacement, leading to the development of cell deformation. In the present study, three different shock-wave sources were investigated; argon fluoride excimer laser, ruby laser, and shock tube. The duration of the pressure pulse of the shock tube was 100 times longer than the lasers. The uptake of two fluorophores, calcein (molecular weight: 622) and fluorescein isothiocyanate-dextran (molecular weight: 71,600), into HL-60 human promyelocytic leukemia cells was investigated. The intracellular fluorescence was measured by a spectrofluorometer, and the cells were examined by confocal fluorescence microscopy. A single shock wave generated by the shock tube delivered both fluorophores into approximately 50% of the cells (p < 0.01), whereas shock waves from the lasers did not. The cell survival fraction was >0.95. Confocal microscopy showed that, in the case of calcein, there was a uniform fluorescence throughout the cell, whereas, in the case of FITC-dextran, the fluorescence was sometimes in the nucleus and at other times not. We conclude that the impulse of the shock wave (i.e., the pressure integrated over time), rather than the peak pressure, was a dominant factor for causing fluorophore uptake into living cells, and that shock waves might have changed the permeability of the nuclear membrane and transferred molecules directly into the nucleus.