Dynamic Simulation And Analysis Of Urinary Flow After Benign Prostatic Hyperplasia Surgery Based On Computational Fluid Dynamics

Background:Benign prostatic hyperplasia(BPH)is a common disease in elderly men.Morphologically,it is a benign enlargement of the prostate due to the unregulated proliferation of epithelial and fibromuscular tissue in the transitional zone of the prostate and the periurethra area.The purpose of benign prostatic hyperplasia surgery is to remove the hyperplastic prostate tissue,relieve the obstruction and reduce the urethral resistance.The shape of the prostate urethra changes before and after surgery.In the past,the evaluation of postoperative urodynamics was limited to the acquisition of urodynamic data such as maximum urine flow rate(Qmax)and bladder pressure.With the extensive application of 3D medical image reconstruction(3DR)and computational fluid dynamics(CFD)in disease analysis.More and more researchers are using computational fluid dynamics analysis software to simulate and analyze hydrodynamics problems encountered in the cardiovascular system,respiratory system and urinary system.As for the study on the changes of urinary flow dynamics after the operation of benign prostatic hyperplasia,some researchers have discussed the feasibility of two-dimensional simulation,but there are few studies on the establishment of three-dimensional model and dynamic computational fluid dynamics simulation.Objective:Based on computational fluid dynamics(CFD)technology,a three-dimensional fluid dynamics model of the posterior urethra was established to simulate the dynamic urination process after benign prostatic hyperplasia,and the results were described and analyzed.Method:One patient with benign prostatic hyperplasia who underwent photoselective vaporization of the prostate(PVP)at our hospital was selected.MRI and urodynamic examination were performed at one month postoperatively.Based on the MRI imaging data,the posterior urethra was modeled in three dimensions using Mimics software and imported into Fluent software,and computational fluid dynamics transient simulations were performed based on urodynamic data with boundary conditions and other parameters.The results are presented in the moment of maximum urinary flow rate according to the calculated results,and cloud maps are drawn in different planes and in the median sagittal plane.Calculate the posterior urethral pressure gradient during voiding.The location of the presence of vortices and the variation of posterior urethral pressure with time were investigated and analyzed.Results:1.The three-dimensional fluid mechanics model of posterior urethra,which can truly reflect the postoperative urethra morphology of prostatic urethra,was established.2.The dynamic voiding process was simulated,and the three-dimensional trajectory of urine,pressure,velocity and velocity vector clouds,turbulent kinetic energy and turbulent intensity clouds,and angular velocity clouds were drawn.3.The pressure gradient of the posterior urethra during urination was calculated.Conclusion:Three-dimensional modeling of the patient’s posterior urethra was performed based on the patient’s post-operative MRI imaging data,and dynamic numerical simulations of the internal flow field of the posterior urethra were performed using computational fluid dynamics techniques to simulate the entire voiding process.A preliminary study of the urinary flow pattern in the posterior urethra was carried out,and the posterior urethral vortex phenomenon was observed,and the posterior urethral pressure gradient changes were studied.The results of the study are expected to be used as a reference in the future to design individualized surgical plans for patients and to provide new ideas for the evaluation of patients’ postoperative surgical outcomes.