Port Size Research Articles

Microlobectomy—where do we stand?

Video-assisted thoracoscopic surgery (VATS) have been shown to be superior to open procedures, particularly with regards to pain and post-operative recovery, though high-levels of pain may still be reported due to large intercostal port sizes. Microlobectomy is a novel endoscopic lobectomy technique building on VATS lobectomies, with the principle that there are no intercostal ports larger than 5 mm. CO 2 insufflation is used to improve access to the chest and a 12 mm subxiphoid port is created to function as a utility port and can be extended further to facilitate specimen removal. All instruments utilized are 5 mm in size, including a 5 mm camera. However, a standard 12 mm stapler can be used through the subxiphoid incision, which provides excellent access to all the hilar structures bilaterally. Additionally, newer instruments are being developed to facilitate easier improved dissection of vascular structures and lymph nodes, such as the FlexDex needle holder, which is an articulated endoscopic needle holder facilitating movements in all directions, similar to a robotic instrument. The main advantage of a microlobectomy is reduced post-operative pain and shorter time to mobilisation, enabling a faster recovery. In our experience of microlobectomies, we have had patients successfully discharged on the first post-operative day. The development of a greater variety of 5 mm instruments that are similar to conventional VATS instruments may enable more surgeons globally to adopt the microlobectomy approach.

Gas Lift Valve R-Ratios

Summary The R-ratio is considered a constant, equal to the area of the port (Ap) divided by the bellows effective area. When gas lift valves are tested for both opening and closing pressures, it is possible to calculate the R-ratio. The calculated R-ratio from test data is consistently larger than the manufacturers’ published R-ratios. This paper presents a discussion of the factors affecting the R-ratio and an explanation for the difference between published and tested R-ratios. The R-ratio is not a constant but varies with dome pressure, port-material strength, bellows size, and port size. A method is proposed to calculate or test the true R-ratio. The use of the area of the port (Ap) in the R-ratio is not completely accurate. The area should be the seal area (As) defined by the outer-sealing diameter of the ball (Ds) on the port. It is possible to test valve behavior to determine the seal area, and it is recommended that the tests be conducted in order to use the correct R-ratio when designing gas lift wells. A method to apply the use of the measured R-ratio is also provided.

A novel technique for superior-based pharyngeal flaps: 10-year results with formal speech outcomes assessment

PurposeDescribe a novel technique for superior-based pharyngeal flaps allowing restoration of bulk to the soft palate and intraoperative fine-tuning of lateral port size, while avoiding midline palate-splitting. Validated speech assessment tools are employed for quantitative analysis. MethodsRetrospective review of all patients who underwent superior-based pharyngeal flap in a 10-year period by a single surgeon. Pittsburgh Weighted Values for Speech Symptoms Associated with VPI and the Goldman-Fristoe Test of Articulation were used for formal speech assessment. Results78 patients met inclusion criteria with clinical data up to 10years postoperatively. 31 patients had congenital velopharyngeal insufficiency (VPI), and the remainder acquired VPI after cleft palate repair or adenoidectomy. 37 patients had a recognized syndrome. All patients noted subjective improvement in nasality, and evaluation with the validated speech assessment tools demonstrated statistically significant improvement in speech. Only one flap takedown was required in a patient with severe midface hypoplasia who developed sleep apnea several years postoperatively. ConclusionsThis technique is successful in congenital and acquired VPI, and in patients with complex craniofacial syndromes. Customization of lateral ports based on preoperative nasopharyngoscopy, and avoidance of a midline palate splitting incision, make this an attractive option for superior-based flap surgery.

Simulation study of multi-chamber rotary compressor

A new multi-chamber rotary compressor (MCRC) has been designed and the simulation result is presented in this paper. MCRC utilizes the space within the cylinder and it has the advantage of being more compact. Mathematical models which include geometrical, thermodynamics, mass flow and discharge valve have been formulated to evaluate the performance of MCRC. Parametric studies have also been carried out to determine the effects of design parameters such as suction and discharge ports size, valve length, valve thickness and valve width on compressor performance. In this paper, mathematical models will be presented and the predictions of the model will be shown and discussed.

연소기 산화제 개폐밸브 재순환예냉 유로의 유량계수 개선

본 논문에서 극저온 추진제를 사용하는 액체추진기관의 재순환예냉 시스템 설계의 유연성을 확보하기 위한 연소기 산화제 개폐밸브 재순환예냉 유로의 유량계수 개선 내용을 소개하였다. 밸브의 재순환 예냉 출구 포트 크기와 밸브 내부 유로 형상 변경에 의한 재순환예냉 유로의 유량계수 값을 예측하기 위해서 기존 밸브에서 측정한 재순환예냉 유로의 유량계수 값들을 활용하였으며, 액체질소를 운용유체로 사용하여 측정한 유량계수와 예측값과의 비교를 통해 밸브 내부 형상 변경에 의한 유량계수 개선정도를 확인하였다. 연소기 산화제 개폐밸브의 재순환예냉 유로의 유량계수는 기존 밸브에 비해 2배가량 향상되었으며, 결과적으로 연소기 산화제 개폐밸브에 할당되었던 설계 요구 차압의 75%가량을 재순환예냉 시스템에서 추가적으로 소요될 수 있는 잠재적인 차압과 재순환예냉 시스템의 다른 구성품의 추가 차압으로 활용될 수 있을 것으로 기대된다. The improvement of a flow coefficient for the recirculation chill-down flow in a main oxidizer shut-off valve has been presented. The flow coefficient, which is mainly affected by the recirculation outlet port size and the configuration inside the valve, has been predicted with measured flow coefficient values. The comparison of experimentally measured flow coefficient with the predicted value shows the effect of valve inside configuration on the flow coefficient. Consequently, the flow coefficient is twice the previous value and about 75% of the pressure loss assigned to the main oxidizer shut-off valve can be used for additional pressure losses for other components in the recirculation chill-down system of a launch vehicle.

Effect of R Ratio on Performance of Injection-Pressure-Operated Gas Lift Valves

Summary An injection-pressure-operated (IPO) gas lift valve's closing force is supplied by a nitrogen charge, acting on the effective area of the bellows (Ab), or a spring force. Traditionally, the opening force is the production pressure acting on the area of the port (Ap) plus the injection pressure acting on the bellows effective area minus the area of the port (Ab − Ap). Traditionally, the ratio Ap/Ab is referred to as the R ratio, and has been considered constant for every valve of the same make, model, and port size. The actual R ratio is not a constant and neither is it equal to the published value. The published R ratios are embedded in all gas lift design programs, and are an integral part of the gas lift design process. This paper describes the consequences of using an assumed R ratio in a gas lift design that is not the same as the actual R ratio of the valve that will be installed in the well.

Performance analysis of a new hypersonic vitrector system.

PurposeTo evaluate porcine vitreous flow and water flow rates in a new prototype hypersonic vitrectomy system compared to currently available pneumatic guillotine vitrectors (GVs) systems.MethodsTwo vitrectors were tested, a prototype, ultrasound-powered, hypersonic vitrector (HV) and a GV. Porcine vitreous was obtained within 12 to 24 h of sacrifice and kept at 4°C. A vial of vitreous or water was placed on a precision balance and its weight measured before and after the use of each vitrector. Test parameters included changes in aspiration levels, vitrector gauge, cut rates for GVs, % ultrasound (US) power for HVs, and port size for HVs. Data was analysed using linear regression and t-tests.ResultsThere was no difference in the total average mean water flow between the 25-gauge GV and the 25-gauge HV (t-test: P = 0.363); however, 25-gauge GV was superior (t-test: P < 0.001) in vitreous flow. The 23-gauge GV was only more efficient in water and vitreous removal than 23-gauge HV needle-1 (Port 0.0055) (t-test: P < 0.001). For HV, wall thickness and gauge had no effect on flow rates. Water and vitreous flows showed a direct correlation with increasing aspiration levels and % US power (p<0.05).ConclusionsThe HV produced consistent water and vitreous flow rates across the range of US power and aspiration levels tested. Hypersonic vitrectomy may be a promising new alternative to the currently available guillotine-based technologies.

횡류식 도로터널의 급배기구 개도율 최적화 프로그램 개발 연구

도심지 터널에 주로 적용되는 횡류식 환기방식은 환기구간 거리가 길어질수록 환기성능이 저하되므로 균일한 풍량분배가 필요하다. 본 연구에서는 환기구간 거리가 길어져도 균일한 풍량분배를 통해 설계값의 환기성능을 확보할 수 있도록 급배기구의 개도율을 최적화하는 프로그램을 개발하였으며, TUNVEN DUCT 프로그램과의 비교를 통해 프로그램의 예측 성능을 검증하였다. 이를 위해 반횡류 급기 환기방식을 적용하였으며, 두 프로그램은 유사한 포트 크기 및 풍량 분배를 예측하고 있으며, 계산값의 변동범위는 각각 11.71% 와 1.36% 인 것으로 나타났다. 이 프로그램은 다양한 터널 연장 및 급배기 포트 설치 조건에 대한 신속한 분석이 가능하므로, 횡류식 및 반횡류 환기방식의 포트 최적화 설계에 상당히 유용할 것으로 판단된다. The transverse ventilation system, commonly applied to urban tunnel, is necessary to be distributed with airflow uniformly. In this study, we developed a program that can optimize the opening ratio of ports to ensure ventilation performance of design criteria through a uniform airflow distribution even though ventilation interval becomes longer. And program's prediction performance was verified by comparison with TUNVEN DUCT program. For comparison, Semi-transverse ventilation system was applied. Both programs predicted a similar port size and air flow distribution, and the variation range of the calculated values was 11.71% and 1.36%, respectively. This program is very useful for port optimization design of transverse and semi-transverse ventilation system, because it is possible to analyze various tunnel lengths and supply/exhaust port installation conditions.

Study of pressure drop in single pass U-type plate heat exchanger

The present work deals with the experimental investigation of the flow maldistribution in a single pass U-type chevron plate heat exchanger using water as a working fluid. Results are presented in terms of total pressure drop, mean channel pressure drop, channel pressure drop and channel velocity for Reynolds number, Re=800–5900, chevron angle, β=60°, and fixed port size of dp=0.0254m for different set of plates, namely, 21 and 27 under two conditions viz. (i) isothermal and (ii) non-isothermal. The present results are also verified with the analytical results of Bassiouny and Martin (1984). Channel pressure drop is observed to be higher for a higher number of plates set. Results also show that the channel pressure drop decreases along the successive channels of the PHE. Deviation of channel pressure drop from mean channel pressure drop verifies the existence of non-uniformity in the flow distribution from port to channels. Higher temperature promotes greater turbulence in the channels leading to higher frictional losses and hence, higher pressure drops. Based on the experimental data, correlations have been developed for friction factor, non-dimensional channel pressure drop and non-dimensional channel velocity.

Reduced-port gastrectomy for gastric cancer with similar port arrangement to conventional five-port laparoscopic gastrectomy

In the recent years, approaches such as reduced-port surgery have garnered much attention because of their minimally-invasive nature and improved cosmetic outcomes. Many different types of reduced-port gastrectomy (RPG) for gastric cancer have been reported, and the optimal port size and their arrangement have not yet been established. The authors perform RPG for gastric cancer using an umbilical multi-channel port (MCP) and two needle forceps. In our procedure, a laparoscope and two 5-mm instruments are inserted through umbilical MCP (GelPOINT). The surgeon stands on the patient’s right side and manipulates the conventional laparoscopic instruments through GelPOINT and right upper abdominal wall needle forceps. The first assistant on the patient’s left side uses the forceps inserted through GelPOINT and the left upper abdominal wall needle forceps. Gastrectomy with lymphadenectomy and reconstruction are performed using the same technique as that of conventional five-port laparoscopic gastrectomy (LG). We have successfully used this procedure in over 60 patients with gastric cancer. Our technique for RPG employs the same number of instruments and similar port arrangement as used in conventional five-port LG. This procedure can also achieve almost the same postoperative pain reduction and excellent cosmetic outcomes as observed with single-port gastrectomy.

Experimental evaluation of mechanical heart support system based on viscous friction disc pump

Aim. Experimental evaluation of the viscous friction disk pump efficiency, studying the relationship between inter-disk clearance and sizes of input and output ports and pump performance parameters.Materials and methods. To assess the characteristics and to optimize the disk friction pump design the pump model and experimental stand were created. Pump dimensions were set on the basis of medical and biological requirements for mechanical heart support systems and with due consideration of the experimental studies of our colleagues from Pennsylvania. Flow volume of the working fluid was measured by float rotameter Krohne VA-40 with measurement error of not more than 1%. The pressure values in the hydrodynamic circuit were measured using a monitor manufactured by Biosoft-M. Expansion device allowed changing the flow resistance of the system simulating the total peripheral resistance of the circulatory system.Results. Linear direct correlation between the pump performance and the pressure drop of liquid being created at the inlet and outlet of the pump was obtained. The required flow rate (5–7 l/min) and pressure (90–100 mmHg) were reached when the rotor speed was in the range of 2500–3000 rev/min. It has been shown that the increase of the inlet diameter to 15 mm has not resulted in a significant increase in the pump performance, and that the highest efficiency values can be obtained for the magnitude of inter-disk gap of 0.4–0.5 mm.Conclusion. Designed and manufactured experimental disc pump model for pumping fluid has showed the fundamental possibility to use this model as a system for mechanical support of the heart.

On the prediction of uniformity of air flow out from manifold distribution

AbstractComputational fluid dynamics (CFD) was used to simulate a closed‐end multiple outlet pipe to examine the effect of different exit port geometry and size of perforation on performance of manifold distribution. To obtain an optimum design, the amount of fluid discharging from any opening in a pipe is greatly concern in engineering applications because uniform flow distribution has significant influence on the performance of manifold distribution. In this investigation, the vertical manifold system was used to study the hydrodynamics of air flow and simulate with computational fluid dynamics (CFD). Firstly, three different exit port geometry (circular, rectangular and square) are chosen to investigate the effect of exit port on mass flow rate uniformity effusing from distribution manifold. The best performance, which most closely approximating uniform outflow was achieved by the rectangle exit ports. Secondly, three different perforation size (3, 4 and 5 mm) of circular exit port were selected to reach to the finding of uniformity. Results show the 5 mm diameter orifices exit port achieve the uniform outflow of all. The ratio of the total opening area for all cases to the cross‐sectional area of the cylindrical pipe is identical for these two cases. Thirdly, the effect of perforation diameter with variable pipe ratio for equal number of orifices was investigated. The analysis for investigating the changes in the discharge angle of the stream between the orifices of multi‐perforated pipes perform for all cases. Standard k–ϵ turbulence model was considered for the numerical simulation, the finding results of numerical simulation were evaluated by the laboratory experiments.

Three port versus four port laparoscopic cholecystectomy- a prospective study

Introduction: Cholelithiasis is the most common and important cause of biliary tract disease. In today’s world, laparoscopic cholecystectomy is the gold standard treatment for gallstones. Decrease in the size or number of ports provide better results in laparoscopic cholecystectomy. Objective: We aim the study to find out feasibility of three port lap cholecystectomy over four port lap cholecystectomy regarding post-op pain, duration of surgery, conversion rate, hospital stay and complications. Materials & Methods: Patients who fulfilled the inclusion criteria were included. 76 patients enrolled for the study and divided into two groups as 3 port and 4 port. Surgical preformed assessment proforma used to collect the data. Results: The mean age of the studied patients was 46.38 years with female preponderance. The Mean operative time for three ports was 66.90 minutes and for four ports it was 75.45minutes. Mean duration of post-operative stay for three port was 4.66 and for the conventional group it was 5.30. Conclusion: Patients who underwent the three port technique had a lesser hospital stay compared to patients who underwent the conventional 4 port technique. Patients had less postoperative pain, lesser requirement of analgesics in three port group. 2 patients from the 4 port group had fever 48 hours after surgery.

Laparoscopic appendectomy using only two 5 mm trocars

Background Laparoscopic appendectomy is now the standard and most surgeons use two 5 mm and one 10–12 mm port; the latter placed into the umbilicus. Various attempts have been made to reduce the number and sizes of ports for this procedure.

Balance between less invasiveness and radical capability with safety

Various types of minimally invasive procedures have been developed for performing a thymectomy and resection of an anterior mediastinal tumor in order to avoid a sternotomy. Those are usually performed with either thoracic or infrasternal (subxiphoid) access. Recently, surgeons have been attempting to reduce the number and size of the access ports with the goal of less injury to the chest wall. A uniportal (single-port) approach is the final state of such so-called reduced port surgery.

Regression Rate Study of Cylindrical Stepped Fuel Grain of Hybrid Rocket

Hybrid rocket propulsion is a rising propulsion system which presents flashy features such as low cost, safety and environment friendliness. On the other side it has certain issues like mixture ratio shifting; low regression rates, mixing inefficiencies, and etc. bound its use as a prime propulsion system. The present analysis presents an approach for rectification of one of the most important among those issues, namely low fuel regression rate. By increasing oxidizer flow speed over the burning fuel surfaces the fuel regression rate can be increased. This is because flow over the burning surface creates shear stress which facilitates fuel and oxidizer mixing. One method of improving shear stress and thus regression rate is to induce an oxidizer vortex into the combustion chamber. The stepped fuel grain configuration is one of the mean to create vortex combustion field in a port. To generate this flow, oxidizer is injected axially in the fuel grain and vortex created inside the grain due to different size of cylindrical port size. A series of static rocket firing were conducted to investigate the solid-fuel regression rate behavior and operating characteristic of stepped solid fuel grain hybrid rocket motor. Results from eight tests of laboratory scale hybrid rocket motor using polyvinyl chloride and gaseous oxygen have been presented here at different oxidizer injections pressures i.e. 16.872, 21.092, 28.122, 42.184, and 48.511 (kgf/cm2) respectively during static rocket test firing. Higher regression rate has been observed in the case of cylindrical stepped fuel grain compare to cylindrical grain.

An optical projection system with mirrors for laparoscopy

We propose an optical projection system aimed at improving laparoscopic surgery based on three-dimensional (3D) measurement that gives an effective information for robotic-assisted surgery and computer-aided surgery. Laparoscopic surgery, which involves the creation of small ports through the patient's body for the laparoscope and surgical instruments, such as clamp, is minimally invasive and has generated a growing interest. There are techniques using the stereo laparoscope to obtain depth information. Active sensing when structured light is added to the laparoscope can reconstruct a 3D shape. However, active sensing that requires projection devices for the structured light leads to an increase in size. Large-sized projection and sensing systems affect surgical procedures. The size of the system is also larger than the size of port for the laparoscope. To remove the obstacle for the surgery, it is important to design downsized systems. For active sensing with the structured light, a small-size projection system is required to use a small port for the laparoscope. Therefore, we built the optical projection system toward downsizing the device to stereoscopic vision of the laparoscope using mirrors, and we show a new shape reconstruction method from its active sensing. Our Experimental results demonstrate the effectiveness of this proposed system and method.

A Study of Port Site Infection Following Laparoscopic Cholecystectomy In a teaching Hospital.

Background/Aims: To assess the port site infections in patients who underwent Laparoscopic Cholecystectomy in the department of Surgery at AGMC and GBP hospital and how to prevent port site infection. Design: Prospective Study Materials and Methods: In this study, a total number of 100 patients who underwent Laparoscopic Cholecystectomy for Chronic Calcular Cholecystitis from January 2015 to June 2016 at our hospital were observed for port site infections. Culture Sensitivity were taken for all patients who developed Port site infections. Variables like Port site, Port size, causative organisms, Surgery-infection interval were analysed. Results: The incidence of port site infection in our study is 7%. The port site infection is more common at Epigastric port site and in 10 mm port size. Most common organisms are staphylococcus aureus followed by Pseudomonas aeruginosa and atypical mycobacterial infection. Conclusion: Port site infections in Laparoscopic Cholecystectomy are minor complication, but still these complications are preventable by proper sterilization of laparoscopic instruments. Keyword : Laparoscopic Cholecystectomy, Port site infection(PSI), Prevention .

Comparison of drill- and needle-based tree injection technologies in healing of trunk injection ports on apple trees

Excessive tree wounding is a common concern regarding the use of trunk injection technology for tree protection purposes in landscapes and urban greening. We investigated the rate of healing of injection ports (points) in apple trees by monitoring parameters such as port diameters, the size of bark cracking, and port depths. We compared drilled injection ports from 4.4 and 9.5mm drill bits, with latter being sealed with plastic-silicone plug (Arborplug®) or not, and the lenticular port from a double-edged blade. Depending on port size and type, port closure ranged from one to more than two years. Bark cracking around injection ports was more pronounced longitudinally. On the sealed 9.5mm port, bark cracking was largely similar to all drilled ports. The depth of port wounds decreased faster on the port from the 4.4mm drill bit and on lenticular injection port versus the unsealed port from the 9.5mm drill bit. Plastic-silicone plugs, which simulate removed bark, slowed the healing of 9.5mm drill port with callus and increased the port depths over time due to callus formation over the top of the plug. From fastest-healing to slowest-healing, on average the injection ports were: lenticular port from blade (70.8%), the unsealed 9.5mm drill port (44.4%), 4.4mm drill port (43.9%), and 9.5mm drill port sealed with plastic-silicone plug (20.4%).

The design and influence of port arrangement on an improved wave rotor refrigerator performance

The port width and the offset between them are important structure parameters of a wave rotor refrigerator (WRR). The arrangement of ports decides the wave diagram in the wave rotor, which has a huge influence on the WRR performance. Designing a wave rotor mainly focuses on predicting the behavior of shock and expansion waves in wave rotor channels. This paper first presents an analytical design procedure for the pressure exchanger refrigerator, also known as WRR, to afford a theoretical port arrangement of the WRR rapidly. Then, the analytical design results are used as initial numerical model for CFD calculation. Based on the numerical simulation results, the port arrangements can be optimized. Charts and explanations are presented for the optimum design. Furthermore, a series of experiments were conducted to investigate the WRR performance under the optimized port sizes and offset. The results suggest that the COP of the system greatly changes with the geometrical arrangements. The highest COP of the system may be reduced by 41.8% with improper port widths or positions. The analysis of the WRR refrigeration system performance has revealed that expansion efficiency can be adversely affected by the compression efficiency, which means the improved WRR system have a great resistance to the working condition of volatility.