目的 基于计算流体力学技术，研究不同程度肾积水中尿液的尿流动力学变化，从而评估肾积水程度对肾脏排石能力的影响。方法 结合有关文献中正常肾盂肾盏和轻、中、重度肾积水中肾盂肾盏的形态学特点及测量数据，应用CAD软件分别绘制分支型肾盂A组，成熟壶腹型肾盂B组，胚胎壶腹型肾盂C组共12个模型。使用ICEM CFD软件分别对各模型进行网格化处理，使用Fluent 17.0对网格化模型进行流体力学分析，使用tecplot 360软件对Fluent仿真结果进行后处理，得到各模型流体力学参数可视化图像。使用SPSS 17.0软件对数据进行分析。结果 A组模型中肾小盏颈部、肾大盏颈部、肾盂出口处流速A1>A2>A3>A4，各组间两两比较差异均有统计学意义（P<0.05）。B组模型中肾小盏颈部、肾大盏颈部、肾盂出口处流速B1>B2>B3>B4，各组间两两比较差异均有统计学意义（P<0.05）。C组模型中肾小盏颈部、肾盂出口处流速C1>C2>C3>C4，各组间两两比较差异均有统计学意义（P<0.05）。A1、B1、C1 3组模型中，尿液在肾小盏颈部的流速两两比较，差别无统计学意义（P＞0.05）。尿液在肾大盏颈部的流速A1组大于B1组，差别有统计学意义（P<0.05）。尿液在肾盂出口处的流速A1、B1组相比差别无统计学意义（P＞0.05）；C1组大于A1、B1组，差别有统计学意义（P<0.05）。A1中肾小盏尿液入口处的循环停滞区最小，A2、A3、A4中入口处尿液的循环停滞区也逐渐增大。另外，由于4组模型中尿液速度梯度逐渐减小，边缘处尿液流动时受管壁的影响越来越大，管壁处的速度边界层也越来越厚。结论 肾积水会导致尿液的尿流动力学发生改变。随着肾积水程度的增加，尿液在肾小盏颈部、肾大盏颈部、肾盂出口处的流速逐渐降低，在肾脏集合系统内的循环停滞区与速度边界层逐渐增大，结石受到的尿液剪切力随之降低，肾脏的排石能力也逐渐下降。因此，在临床中选择肾结石治疗方式时，应该充分考虑到不同程度肾积水对患者术后排石能力的影响，从而选择更合适的治疗策略。
Objective The urodynamic changes of urine at different degrees of hydronephrosis were studied through the computational fluid dynamics technology to evaluate the influence of the degree of hydronephrosis on the kidneys’ ability to discharge the stones. Methods Using the related literature, we combined the morphological characteristics and measurement data of the normal renal pelvis and calyx at different degrees of hydronephrosis and drew Model A (branched pelvis group), Model B (mature ampullary pelvis group), and Model C (embryo pot abdominal pelvis group) using the CAD software. The ICEM CFD software was used to create a mesh in each model and Fluent 17.0 was used to perform hydromechanical analysis for the meshed models. In order to obtain a visualized image of the hydrodynamic parameters of each model, the Tecplot 360 software was used, which post-processed and visualized the Fluent simulation results. Data were analyzed using SPSS 17.0 software. Results In the group A model, the flow velocity at the outlet and the neck of the calyces, and the outlet of the renal pelvis was A1> A2> A3> A4 (P <0.05). Similarly, in the group B model, the flow velocity at the outlet and the neck of the calyces, and the renal pelvis was B1> B2> B3> B4 (P <0.05). In the C group model, the flow velocity at the outlet of the calyces and the renal pelvis was C1> C2> C3> C4 (P <0.05). In the groups, A1, B1, and C1, the flow rate of urine in the neck of renal calyx were compared in pairs (P> 0.05) and was found to be greater in group A1 compared to the group B1 (P <0.05). There was no significant difference in urine flow rate at the outlet of the renal pelvis between the groups A1 and B1 (P> 0.05), while the flow rate of urine in the C1 group was greater than both A1 and B1 groups (P <0.05). The circulatory stagnation zone at the entrance of renal calyces in the group A1 was the smallest, whereas it gradually increased in the groups A2, A3, and A4. Also, due to the gradual decrease of the urine velocity gradient in the four model groups, the urine flow at the edge was increasingly affected by the wall of the tube, eventually thickening its velocity boundary layer. Conclusion Hydronephrosis can cause changes in the urodynamics of urine. As the degree of hydronephrosis increases, the flow velocity of urine at the neck of the kidney, the outlet of the renal pelvis, the urinary shearing force of the stones, and the kidney’s ability to discharge the stones gradually decreases, whereas the circulatory stagnation zone and the velocity boundary layer in the kidney aggregate system gradually increases. Therefore, the effect of different degrees of hydronephrosis on the patient’s ability to discharge stones after surgery should be fully considered to choose an appropriate treatment method for kidney stones in the clinic.