PM2.5 is an important factor to affect the patients with respiratory and cardiovascular diseases. Clinical studies have found that the morbidity and mortality of patients with heart failure (HF) have a close relationship with the movement and deposition state of PM2.5. One reason is that the breathing pattern of patients with HF has obvious difference with healthy people, however the effect caused by these differences on the distribution regularity of PM2.5 in the respiratory tract is still unclear. Hence, a computational fluid dynamics simulation was conducted to clarify the aerodynamic effect of breathing pattern of patients with HF on respiratory system. Ideal upper respiratory tract geometric model was established based on standardized aerosol research laboratory of Alberta and Weibel A dimension. The discrete phase method is used to calculate the movement of the airflow and particles. The flow rate were chosen as the inlet boundary conditions, and the outlets are set at a constant pressure. The rate of particle deposition, distribution location, wall pressure, flow velocity and wall shear stress are obtained, and compared to the normal control. The results demonstrated that the rate of escaped particles in every bronchial outlet of the patients with HF was more than the normal controls, meanwhile the trapped was less (1024 < 1160). There was higher by 12.9% possibility that the PM2.5 entered the lungs than the normal control. The aerodynamic performances of HF patients are different from normal control. Compared to the normal control, under similar environment, there is higher possibility of PM2.5 moving into lungs, and these particles could affect the function of the respiratory system, resulting in the deterioration of the state of cardiovascular system. In short, it’s necessary to pay more attention to the living environment of HF patients, to reduce the content of PM2.5 particles in the air, and reduce the damage of PM2.5 particles caused by breathing patterns.

Background: The STM CP-24 I centrifugal pump is a newly developed centrifugal pump for extracorporeal membrane oxygenation equipment. This study aimed to combine hydraulic experiments, hemodynamic numerical simulations, and standard in vitro hemolysis experiments to investigate the comprehensive performance of this centrifugal pump. Methods: In vitro experiments were first done to obtain the pressure-flow data of the centrifugal pump in its working range to evaluate its hydraulic performance. Next, the commonly used clinical working points were selected as boundary conditions, and a computational fluid dynamics method was applied to evaluate its hemodynamic performance. The blood pressure distribution, blood flow fields, and high-wall-shear-stress zones in the centrifugal pump were determined as indicators for hemodynamic evaluation. Finally, standard in vitro hemolysis experiments were performed to test the blood compatibility of this centrifugal pump (n=3 blood samples). In addition, its blood compatibility was evaluated in the form of the normalized index of hemolysis (NIH). Results: The pressure-flow curve of the centrifugal pump showed that the head pressure and flow of the centrifugal pump showed a mostly linear relationship within the whole working range. When the rotation speed of the centrifugal pump was 5,500 rpm, it achieved a hydraulic performance of 550 mmHg head pressure and 8 L/min output flow, which could meet the clinical needs of extracorporeal membrane oxygenation. Analysis of computational fluid dynamics data indicated that the centrifugal pump had excellent hemodynamic performance: even distribution of blood pressure in the pump, no blood flow stagnation zone or dead zone in the overall flow field, and secondary flows in the gap between the rotor and the volute that significantly reduced the volume of the low-blood-flow zone close to the impeller. There was no obvious high-shear-stress zone on the surface of the volute or the impeller, which will effectively reduce the risk of thrombosis. In vitro hemolysis experiments indicated that the centrifugal pump had excellent blood biocompatibility, with a NIH =0.0125±0.0022 g/100 L. Conclusions: The STM CP-24 I centrifugal pump has excellent hydraulic performance, a reasonable design of the hemodynamic structure of the blood pump, and excellent blood compatibility. Therefore, it can meet clinical needs.

Sigmoid sinus diverticulum (SSD) is a common pathophysiology of pulsatile tinnitus (PT) and mainly treated by SSD reconstruction surgery. The degree of reconstruction is an important indicator of SSD reconstruction surgery, but its impact on the effect of SSD reconstruction is unclear. This study aimed to clarify the effect of the degree of SSD reconstruction on diverticulum reconstruction surgical treatment. One patient-specific case (control subject) was reconstructed based on the computed tomography angiography (CTA) images of patients with PT. The SSD reconstruction degree was used as a new index in this study. And the case of 30% (case 1), 60% (case 2), and 100% (case 3) of the diverticulum reconstruction degree of control subject were constructed. Transient-state computational fluid dynamics was performed. Wall pressure distribution, wall average pressure (P_avg) of SSD, flow pattern (velocity streamlines and velocity vector), wall shear stress (WSS) and averaged WSS (WSS_avg) were calculated and used in evaluating the hemodynamic differences among the DRD cases. Results demonstrated that change in SSD pressure was not linear with increase in DRD. The DRD that reached 60% of the original diverticulum was effective. At the peak point of the inlet boundary condition (T1 = 0.22s), the P_avg of SSD had a nonlinear change (control subject, 126.967 Pa vs. case 1, 126.274 Pa vs. case 2, 106.897 Pa vs. case 3, 94.116 Pa). Flow vorticity decreased gradually, and the smoothness of the streamlines increased with DRD. WSS_avg slightly changed with increasing DRD. The high-speed flow blood hit the diverticulum entrance and then swirled to hit the area of the sigmoid sinus wall abnormal. It was concluded that flow patterns related to PT differ with DRD. In diverticulum reconstruction surgery, there is a threshold value, and only when the DRD exceeds this value (60% or 70% or 80%), it will have a noticeable effect. In this study, DRD should at least reach 60% of the original diverticulum. When DRD is insufficient, hemodynamic change in the diverticulum is small, and the PT may have remained. SSD may be caused by high-speed blood flow.