Lateral Orifice Research Articles

Ureteral stents: What your eyes can’t see! An in vitro study

ObjectivesTo characterize and compare in vitro the surfaces of ureteral stents (STENTS) before utilization. MethodsOur in vitro experiment included six unused STENTS models: three double-pigtail with side orifices (ImaJin and Stenostent [Coloplast©,France], TriaSoft [BostonScientific©,USA]), two double-pigtail without side orifice (Vortek-TumorStent [Coloplast©,France], Urosoft-TumorStent [Bard-Angiomed©,Germany]) and one single-pigtail (J-Fil [Rocamed©,Monaco]). STENTS were made of polyurethane except for ImaJin (silicone). For all STENTS, four parts of the stent were specifically analyzed under high-resolution scanning electron microscopy (HR-SEM,FEI-XL40 [Philips©,France]): surface core, lateral orifice, ureteral loop, and black marking surface. Each experiment was repeated with three different samples from three different stents. STENTS analysis included multiple imperfection searches, defined as irregularities>10μm. ResultsAll STENTS presented imperfections with no discernible differences. Imperfections were mainly located on the stent loop and on the lateral orifice. For STENTS without side orifice (J-Fil, Urosoft) imperfections were also reported, on the beveled cut as well as the distal loop orifice. Marking surfaces examinations found defects in the Urosoft and imperfections in the ImaJin and Stenostent. The Triasoft presented a better smoothness on marking surfaces compared to other STENTS. Additional matter was reported on the loop distal orifice for J-Fil and ImaJin but all STENTS presented irregular cross-sectional aeras. ConclusionAll ureteral stents are not perfectly smooth even before utilization. Imperfections were noticed regardless to stent composition or shape, and could play a role in the incrustation phenomenon, is association with inner irregularities, infection, and urine composition. Both manufacturing and material could have an impact on the stent external surface's smoothness. Level of evidence3

Endoscopic approach to complex or recurrent pilonidal sinus: A retrospective analysis.

Pilonidal Sinus is a benign, chronic disease that affects the hair follicles of the natal cleft of the sacrococcygeal area. Its ideal treatment is controversial, especially in complex or recurrent cases. The aim of this study is to evaluate the use of minimally invasive endoscopic approach in this setting. We enrolled patients affected by complex or recurrent sacrococcygeal pilonidal sinus from January 2015 through December 2020 who underwent Video-Assisted Ablation of Pilonidal Sinus. All patients enrolled were re-evaluated once a year with a standard physical examination. The patients included were 38. Recurrence rate at 1-, 3- and 5-years follow-ups were 28.9%, 22.2% and 38.1% respectively. Of interest, the mean (SD) distance from the most lateral orifice to the midline was higher in group of patients with recurrence and the multivariate analysis demonstrated that it was the limiting factor, which influences the recurrence rate. In complex or recurrent pilonidal sinus disease with pits off the midline the endoscopic approach should not be the first choice. This makes us think that these cases should have their own classification to be identified and guide surgeons in choosing the appropriate approach.

Granular mixtures discharging through a silo with lateral orifice

Here, we studied the flow dynamics of a mixture of dumbbells and disks flowing through an orifice situated on the lateral wall of a two-dimensional silo using the discrete element method. When two constituent parts of a dumbbell are simultaneously in contact with either a disk or one part of another dumbbell, it hinders the relative motion of both the particles. An increase in the fraction of dumbbells increases the number of contacts exhibiting the aforementioned mechanism, thus increasing the dynamic friction. This leads to a decrease in the flow rate with an increase in the fraction of dumbbells. To relate the flow rate with the fraction of dumbbells and the orifice width, we proposed modified Beverloo's law scaling. Moreover, we presented coarse-grained flow fields, which reveal the presence of stagnant zones that hinder the free flow of particles adjacent to them.

Treating Mitral Valve Prolapse in Barlow's Disease by Creation of a Medial MitraClip Bridge and a "New" Lateral Orifice: Rationale for MitraClip NTR Adoption.

Percutaneous mitral valve repair with MitraClip XTR (Abbott Vascular) has been proposed in patients with Barlow's disease, as the extended length of the MitraClip XTR may facilitate "grasping" and limit the number of clips. However, the design of the MitraClip XTR includes arms that 3 mm longer than the NTR device as well as 2 additional frictional elements, and requires a patient selection based mainly on mitral valve tissue quality. We summarize our rationale for using the shorter and smaller MitraClip NTR in patients with Barlow's disease.

Discharge of a silo through a lateral orifice: Role of the bottom inclination versus friction.

In this work we propose to identify the relative role of the inclination of gravitational acceleration and friction on the discharge flow rate of a granular media from a rectangular silo by varying the silo geometry thanks to an inclined bottom which ends up at a lateral outlet. The study is motivated by a nuclear safety problem: a fuel rod (modeled by an elongated silo) accidentally releases fuel fragments (modeled by grains). We performed experiments where we independently measured the mass flow rate and the velocity profiles, together with discrete particle simulations and continuum simulations with a frictional rheology described by a μ(I) constitutive law and taking into account the wall friction. We study monolayer flows and three-dimensional flows, and we propose an analytical model that predicts the discharge flow rate of particles from a rectangular silo with an inclined bottom according to its outlet aspect ratio and the bottom inclination angle.

Discharge flow of granular media from rectangular silos: role of an obstacle and modelling by an orifice at the corner

We present an experimental study on the discharge flow of a granular media from a rectangular silo with a cylindrical obstacle placed above the outlet. As described in the literature, the presence of an obstacle decreases the flow rate, but the characteristic lengths to be chosen in the flow rate law are not known. To predict the flow rate we vary the obstacle diameter and vertical position, the outlet size and the particle diameter. However due to the large number of parameters we find that the characteristic length which controls the flow rate cannot be thoroughly defined. To model the effect of an obstacle on the flow rate we design a new configuration with an orifice at the corner of the silo. We study the two extreme cases (a bottom orifice at the wall and a lateral orifice) and we show that for the corner all the data are in between these two cases.

Right upper lobe anatomy revisited: a computed tomography scan study.

The double lumen tube (DLT) has become the most popular way to isolate the lungs for thoracic surgery. The variable anatomy of the right main stem bronchus (RMSB) seems to be the main reason clinicians are unwilling to use the right-sided DLT (R-DLT). The factors that could compromise the adequate ventilation of the right lung are mostly the variable length of the RMSB and the misalignment of the lateral orifice of the R-DLT in regard to the right upper lobe bronchus (RULB). The objectives of this study were to validate an alternative method to estimate the RMSB length, and to determine the distribution of the angulation of the ostium of the RULB. From high-resolution computed tomography scans of the thorax of 106 consecutive patients, the length of the RMSB was measured using Kim's method and the carina-to-carina method. The angle between the RULB origin and the lateral aspect of the RMSB was also measured. All these measurements were correlated and inter-observer variation documented. From the Kim's method, the mean (standard deviation [SD]) length of the RMSB was 25.5 (4.7) mm. From the alternative carina-to-carina method, the mean (SD) length of RMSB was 29.4 (4.6) mm. The inter-observer agreement was substantial with both methods (Kim's method: intraclass correlation coefficient [ICC] = 0.84; carina-to-carina method: ICC = 0.95). Both measures were closely related (ICC = 0.93; P < 0.001). The RULB presented a wide range angulation [mean (SD), 0.1 (9.5)°; range, -28.6 to 21.2]. These anatomic observations provide a better understanding of the variable anatomy of the right bronchial tree and may guide thoracic anesthesiologists in the choice of the best lung isolation device for their patients.

Experiments on, and discrete and continuum simulations of, the discharge of granular media from silos with a lateral orifice

We compare laboratory experiments, contact dynamics simulations and continuum Navier–Stokes simulations with a $\unicode[STIX]{x1D707}(I)$ visco-plastic rheology, of the discharge of granular media from a silo with a lateral orifice. We consider a rectangular silo with an orifice of height $D$ which spans the silo width $W$, and we observe two regimes. For small enough aperture aspect ratio ${\mathcal{A}}=D/W$, the Hagen–Beverloo relation is obtained. For thin enough silos, ${\mathcal{A}}\gg {\mathcal{A}}_{c}$, we observe a second regime where the outlet velocity varies with $\sqrt{W}$. This new regime is also obtained in the continuum simulations when the friction on side walls is taken into account in a thickness-averaged version of $\unicode[STIX]{x1D707}(I)$ $+$ Navier–Stokes (in the spirit of Hele-Shaw flows). Moreover most of the internal details of the flow field observed experimentally are reproduced when considering this lateral friction. These two regimes are recovered experimentally for a cylindrical silo with a lateral rectangular orifice of height $D$ and arc length $W$. The dependency of the flow rate on the particle diameter is found to be reasonably described experimentally using two geometrical functions that depend respectively on the number of beads through the two aperture dimensions. This is consistent with two-dimensional discrete simulation results: at the outlet, the volume fraction and the velocities depend on the particle diameter and this behaviour is correctly described by those geometrical functions. A similar dependency is observed in the two-dimensional continuum simulations.

Discharge flow of granular media from silos with a lateral orifice and injection of air

Few studies concern the prediction of the mass flow rate of a granular media discharged from a silo with a lateral orifice. However, this situation can have pratical interest considering a tank of granular material with a leak on its side. We studied experimentally the discharge of a vertical silo filled by spherical glass beads. We consider rectangular silos with a rectangular orifice. The impact of size, aspect ratio and position of the orifice and the effect of an additional air flow were studied. The measured parameters are the mass flow rate and the pressure along the silo, whereas the controlled parameters are the size of particles, and the flow rate of air. We identified two regimes of discharge according to the aspect ratio (of width to height) of the rectangular orifice. Increasing the air flow rate induces an increase of the granular media flow rate. Using a simple physical model to describe the grains and gas flow, we put in evidence the role played by the air pressure gradient at the outlet. Then we compared the experimental results with continuum Navier-Stokes simulations with the granular μ (I)-rheology. We showed that the continuum μ (I)-rheology describes well our discharge flow of granular media from silos, taking into account the effect of the position of the orifice as well as the coupling with the gas flow.

A novel computational model for the hemodynamics of bileaflet mechanical valves in the opening phase.

A powerful alternative means to study the hemodynamics of bileaflet mechanical heart valves is the computational fluid dynamics method. It is well recognized that computational fluid dynamics allows reliable physiological blood flow simulation and measurements of flow parameters. To date, in almost all of the modeling studies on the hemodynamics of bileaflet mechanical heart valves, a velocity (mass flow)-based boundary condition and an axisymmetric geometry for the aortic root have been assigned, which, to some extent, are erroneous. Also, there have been contradictory reports of the profile of velocity in downstream of leaflets, that is, in some studies, it is suggested that the maximum blood velocity occurs in the lateral orifice, and in some other studies, it is postulated that the maximum velocities in the main and lateral orifices are identical. The reported values for the peak velocities range from 1 to 3 m/s, which highly depend on the model assumptions. The objective of this study is to demonstrate the importance of the exact anatomical model of the aortic root and the realistic boundary conditions in the hemodynamics of the bileaflet mechanical heart valves. The model considered in this study is based on the St Jude Medical valve in a novel modeling platform. Through a more realistic geometrical model for the aortic root and the St Jude Medical valve, we have developed a new set of boundary conditions in order to be used for the assessment of the hemodynamics of aortic bileaflet mechanical heart valves. The results of this study are significant for the design improvement of conventional bileaflet mechanical heart valves and for the design of the next generation of prosthetic valves.

Pilonidal sinus surgery: could we predict postoperative complications?

Pilonidal sinus surgery could, as of now, be considered a surgery tailored more to the surgeon than to the patient. In an attempt to give to surgeons an objective instrument of decision, we have evaluated which variables could be considered predictive of postoperative complications after pilonidal sinus surgery. A prospective electronic database of all patients treated for sacrococcygeal pilonidal disease was analysed. Sex, age, obesity, smoking, recurrent disease, the presence of multiple orifices and the distance between the most lateral orifice and midline were recorded and correlated with the occurrence of postoperative complications (infection and recurrence); 1006 patients were evaluated. Excision with primary mid-line closure was performed on all the patients. Mean follow-up was 7·3 ± 3·6 years. A total of 158 patients with postoperative complications (infection and/or recurrence) were recorded during this period. A multivariate analysis showed that, after adjusting for major clinical and demographic characteristics, only a recurrent disease [odds ratio (OR): 3·41, 95% confidence interval (CI): 1·89-6·15, P < 0·001] and the distance of lateral orifice from midline (OR: 26·3, 95% CI: 12·2-56·7, P < 0·001) were independent predictors of overall postoperative complications. Focussing on the distance from midline, the receiver operative characteristic (ROC) analysis showed that the distance of lateral orifice from midline predicted 79·2% of complications and the Youden's test identified the best cut-off as 2·0 cm for this variable. An evidence-based tool for deciding on the type of surgical intervention could be developed and validated by further ad hoc prospective studies evaluating our results in comparison to other different types of surgical techniques. Our results support the use of these variables as an effective way to tailor pilonidal sinus surgery to the patient, so as to obtain the best results in patient care.

Analysis of flow through lateral rectangular orifices in open channels

A side lateral orifice in open channel is hydraulic control structure widely used in hydraulic, irrigation and environmental engineering for diverting the flow from main channel to a secondary channel. In this paper, analytical relationships for the discharge through side orifice are developed accounting for the pressure distribution over the area of the orifice. The computed discharges using the proposed relationship are within ±5% of the observed values; however percentage error is more in case the discharge is computed using earlier equations.

Huber Cannula Releases Silicone Particles From Port

The article purports to present the most important studies on complications in port catheter systems from the past 10 years. This may be the reason for the error when the authors write that Huber needles, which are used for puncture through the port system’s silicone membrane, are non-punching. As early as in 1988, Haindl and Muller (1) as well as Muller and Zierski (2) were able to show that the Huber cannula, which was developed in the 1950s, releases silicone particles from the port septum. These particles pose a problem not only for port systems themselves, but also for patients as they may be able to reach their circulatory system. Our own studies into standard port cannulas, Huber cannulas, and punch-free cannulas showed that in 100 punctures with a Shore hardness of 80, large particles were punched by standard port cannulas, small particles by the Huber cannula, and 0 particles when using punch-free cannulas. Alternatives to the Huber cannula are available. The critical lower end of the Huber bevel has been modified to decreased sharpness (3). Other manufacturers have provided styles to protect the needle tip, for instance by using a mandrin, which is effective but costly. Another solution is a non-bending needle tip with a lateral orifice as found in punch-free needles. This is 100% effective in preventing punch defects regardless of Shore strength.

Lateral Orifice of Prussak's Space Assessed With a High-Resolution Cone Beam 3-Dimensional Computed Tomography

To describe how to obtain high-resolution computed tomography (CT) images of the en face view of the lateral orifice of Prussak's space (Ps orifice) and tympanic ring and to investigate the shape and size of these structures in normal ears and in those with chronic otitis media and attic cholesteatoma. University-affiliated referral center. Using the Accuitomo image reconstruction algorithm, the slope of the eardrum was turned to vertical on both coronal and axial images. A sagittal slice view at the eardrum gave the en face view of the eardrum. The width and height of the Ps orifice and vertical axis of the tympanic ring were measured with an automatic measuring device. In the normal Ps orifice, the height is less than 1.30 mm, and the width is less than 2.63 mm. The height and width in the Ps orifice with attic cholesteatoma were significantly larger than those in normal ears and in ears with COM (p < 0.01). In the ears with COM, the width and height on average seemed larger than normal, but no significant difference was verified. The vertical axis of the tympanic ring was unaffected by the diseases. CT imaging of the en face view of the Ps orifice obtained by the present method is useful as an objective measure to assess bone destruction at the Ps orifice, a scutum defect, in ears with COM and attic cholesteatoma.

Numerical and experimental investigations of pulsatile blood flow pattern through a dysfunctional mechanical heart valve

Around 250,000 heart valve replacements are performed every year around the world. Due their higher durability, approximately 2/3 of these replacements use mechanical prosthetic heart valves (mainly bileaflet valves). Although very efficient, these valves can be subject to valve leaflet malfunctions. These malfunctions are usually the consequence of pannus ingrowth and/or thrombus formation and represent serious and potentially fatal complications. Hence, it is important to investigate the flow field downstream of a dysfunctional mechanical heart valve to better understand its impact on blood components (red blood cells, platelets and coagulation factors) and to improve the current diagnosis techniques. Therefore, the objective of this study will be to numerically and experimentally investigate the pulsatile turbulent flow downstream of a dysfunctional bileaflet mechanical heart valve in terms of velocity field, vortex formation and potential negative effect on blood components. The results show that the flow downstream of a dysfunctional valve was characterized by abnormally elevated velocities and shear stresses as well as large scale vortices. These characteristics can predispose to blood components damage. Furthermore, valve malfunction led to an underestimation of maximal transvalvular pressure gradient, using Doppler echocardiography, when compared to numerical results. This could be explained by the shifting of the maximal velocity towards the normally functioning leaflet. As a consequence, clinicians should try, when possible, to check the maximal velocity position not only at the central orifice but also through the lateral orifices. Finding the maximal velocity in the lateral orifice could be an indication of valve dysfunction.

Modified and Newly Designed Right-sided Double-lumen Endobronchial Tubes Are Complementary

University Heart and Lung Institute at Laval Hospital, Quebec City, Quebec, Canada. jean.bussieres@anr.ulaval.caWe read with great interest the case report1on the application of a newly designed right-sided, double-lumen endobronchial tube (R-DLT) in patients with a very short right mainstem bronchus.However, in citing our work2on the improvement of the endobronchial positioning of the R-DLT, Hagihira et al. stated that we modified the design of the bronchial cuff and that these changes seem to offer little improvement. This statement is inconsistent with our published manuscript which demonstrates, on a randomized series of 80 patients, that the modified enlarged area of the lateral orifice (and not the bronchial cuff as stated by Hagihira et al. ) improve the success rate of final positioning from 74 to 97% with a P &lt; 0.0109. These two new versions of the R-DLT are not intended to solve the same problem, but the final objective, improvement of the use of R-DLT, is similar.We thank Dr. Hagihira for this interesting case report. While this new R-DLT may become a useful tool for thoracic anesthesiologists, we would first encourage them to validate its use with a randomized study.University Heart and Lung Institute at Laval Hospital, Quebec City, Quebec, Canada. jean.bussieres@anr.ulaval.ca

Analytical and numerical analysis of the liquid longitudinal sloshing impact on a partially filled tank-vehicle with and without baffles

A new analytical model of longitudinal liquid sloshing is developed using the Navier-Stokes theoretical equations and the principle of work and energy for tank models with lateral orifice baffles. The analyses are performed under varying magnitudes of longitudinal accelerations of the tank, and using two different fills. The results obtained are compared with the simulation results obtained using the full complex Navier-Stokes equations. The comparison is presented in terms of mean and peak of longitudinal and vertical shift of the centre-of-mass coordinates and also in terms of longitudinal pressure force and mass moment inertia variations.

Modified right-sided Broncho-Cath™ double lumen tube improves endobronchial positioning: a randomized study

ObjectiveA left-sided double lumen tube is recommended for one-lung ventilation for most thoracic surgeries, but for certain indications, a right-sided double lumen tube (R-DLT) may be mandatory. Frequent malposition of R-DLTs has been reported. We propose an innovative modification of Mallinckrodt’s Broncho-Cath™ R-DLT consisting of an enlarged area of the lateral orifice, and studied the impact of this modification on the adequacy of R-DLT positioning.MethodsEighty adult patients scheduled for elective thoracic surgery were randomized into two groups: standard Broncho-Cath™ R-DLT, or modified Broncho-Cath™ R-DLT. After induction of anesthesia, the R-DLT was positioned using a fibreoptic bronchoscope. The position of the R-DLT was assessed on three occasions: with the patient supine (T1), then immediately following the patient’s transfer to the lateral position (T2), and after repositioning of the tube, when needed, with the patient in lateral position (T3). A score ranging from 1 to 4 was accorded to the relative position of the right upper lobe (RUL) orifice in relation to the origin of the RUL bronchus.ResultsThe modified Broncho-Cath™ R-DLT was more frequently in an adequate position at T2: 77% vs 37% of patients (P = 0.0121), and easier to reposition at T3: 97% vs 74% of patients (P = 0.0109) in comparison to the standard Broncho-Cath™ R-DLT group.ConclusionThese data suggest the superiority of the modified Broncho-Cath™ R-DLT compared to a standard Broncho-Cath™ R-DLT for optimal R-DLT positioning to facilitate one-lung ventilation during thoracic surgery.

Preliminary MRI study on hemodynamics after prosthetic cardiac valve implantation

目的 应用MRI测量人工心脏瓣膜远端血流野及三维图像的描绘,来评价人工心脏瓣膜功能,并为长期随访瓣膜血栓等并发症的出现和发展提供原始资料.方法27例人工主动脉瓣膜置换患者进行MR血流速度测量检查,置换双叶机械瓣20例,单叶机械瓣7例.于升主动脉内距主动脉瓣环0.5、1.0及2.0个人工瓣环直径处进行血流速度测量.应用血流分析及Matlab 6.5软件进行二维及三维血流图形重组.结果16例置换Sorin双叶机械主动脉瓣患者,三维血流图人工心脏瓣膜的形状特点为近似对应于2个瓣孔及2个瓣叶之间缝隙的3个喷射峰;4例置换Sorin双叶机械主动脉瓣患者,出现对应于2个瓣孔的双喷射峰.20例置换双叶机械主动脉瓣患者,血流速度在加速射血相及最大射血相血流速度图变成倾斜.7例置换单叶机械主动脉瓣患者在收缩加速相见对应单叶瓣口的1个主喷射峰.26例反向血流出现在人工瓣膜侧孔的位置.MR血流速度三维图反映了人工心脏机械瓣膜的设计形状.距主动脉瓣环1.0人工瓣环直径处的轴向血流速度图较远端(2.0人工瓣环直径处)及近端(0.5人工瓣环直径处)的轴向血流速度图能更详细反映人工瓣膜的设计形状.结论MR可以无创、直观、在体地了解瓣膜功能,为发现术后并发症奠定基础。

Echocardiographic characteristics of transprosthetic blood peak velocity in the Sorin Bicarbon bileaflet prosthetic heart valve

The Bicarbon prosthetic heart valve with two curved leaflets is designed so that the blood flows through the three orifices are parallel jets of equal size. This study was conducted to confirm that the Bicarbon valve functions clinically as designed. Forty-three patients underwent valve replacement with the Bicarbon valve. Forty-eight Bicarbon valves were implanted: 25 valves in the mitral position and 23 in the aortic position. Peak blood flow velocity through the three prosthetic orifices was measured postoperatively by Doppler echocardiography. The three flow jets through the prosthesis were parallel. The velocity through the lateral orifice was 2.33±0.38 m/min, and the velocity through the central orifice was 2.14±0.43 m/min at the aortic position (P>0.05). The velocity through the lateral orifice was 1.72±0.06 m/min at the mitral position, and that through the central orifice was 1.73±0.06 m/min (P>0.05). Serum lactic acid dehydrogenase values were also lower than those of patients or whom another bileaflet prosthesis had been implanted. The results confirm that the Bicarbon prosthetic heart valve performs clinically as designed, producing three parallel blood flow jets with equal flow velocity.