Outflow Capacity Research Articles

Management of vascular access inflow-outflow imbalance: A bimodal approach.

A more accurate descriptive and clinically useful diagnosis based upon pathophysiology for what is commonly referred to as venous outflow stenosis is inflow-outflow imbalance. In these cases, the total outflow capacity of the AV access is inadequate to handle the inflow volume (Qa) without an increase in pressure. The relative inadequacy of the access outflow capacity in comparison to Qa results in increased outflow resistance and a proportional increase in intraluminal pressure. The clinical indicators associated with venous stenosis are the resulting manifestations of this imbalance. The point at which this occurs is dependent upon variations in these two parameters-Qa and outflow resistance. The variations in these two parameters are considerable and reciprocal. Excessive Qa results in or can lead to an entire list of serious problems that adversely affect patient morbidity and mortality. Most studies dealing with AV access Qa reduction have been for the treatment of an existing condition rather than its prevention; however, prevention of disease rather than waiting for its development is an important tenet of medical practice. The resulting clinical picture of inflow-outflow imbalance is taken as an indication for corrective treatment. In the past, in most cases this has meant angioplasty to open the outflow if it is reduced; however, this clinical picture may be associated with an excessive Qa and angioplasty in these cases creates the risk for a further increase in Qa. It is the authors' opinion that access flow measurements should be a part of the evaluation of these cases prior to planning treatment. Using this information, a bimodal approach to primary treatment should be adopted involving either angioplasty for cases with a low or normal Qa or flow reduction in cases with an elevated Qa.

Development and Verification of a Novel Three-Dimensional Aqueous Outflow Model for High-Throughput Drug Screening.

Distal outflow bleb-forming procedures in ophthalmic surgery expose subconjunctival tissue to inflammatory cytokines present in the aqueous humor, resulting in impaired outflow and, consequently, increased intraocular pressure. Clinically, this manifests as an increased risk of surgical failure often necessitating revision. This study (1) introduces a novel high-throughput screening platform for testing potential anti-fibrotic compounds and (2) assesses the clinical viability of modulating the transforming growth factor beta-SMAD2/3 pathway as a key contributor to post-operative outflow reduction, using the signal transduction inhibitor verteporfin. Human Tenon's capsule fibroblasts (HTCFs) were cultured within a 3D collagen matrix in a microfluidic system modelling aqueous humor drainage. The perfusate was augmented with transforming growth factor beta 1 (TGFβ1), and afferent pressure to the tissue-mimetic was continuously monitored to detect treatment-related pressure elevations. Co-treatment with verteporfin was employed to evaluate its capacity to counteract TGFβ1 induced pressure changes. Immunofluorescent studies were conducted on the tissue-mimetic to corroborate the pressure data with cellular changes. Introduction of TGFβ1 induced treatment-related afferent pressure increase in the tissue-mimetic. HTCFs treated with TGFβ1 displayed visibly enlarged cytoskeletons and stress fiber formation, consistent with myofibroblast transformation. Importantly, verteporfin effectively mitigated these changes, reducing both afferent pressure increases and cytoskeletal alterations. In summary, this study models the pathological filtration bleb response to TGFβ1, while demonstrating verteporfin's effectiveness in ameliorating both functional and cellular changes caused by TGFβ1. These demonstrate modulation of the aforementioned pathway as a potential avenue for addressing post-operative changes and reductions in filtration bleb outflow capacity. Furthermore, the establishment of a high-throughput screening platform offers a valuable pre-animal testing tool for investigating potential compounds to facilitate surgical wound healing.

Exploring the Sensitivity of the Transient Response following Power Failure to Air Valve and Pipeline Characteristics

Air valves are protective devices often used in pressurised water pipelines, ideally admitting air to limit sub-atmospheric pressures and controlling the release of entrapped air. This work summarises a comprehensive sensitivity analysis of the transient behaviour in a rising water pipeline with an air valve following a pump trip. The paper examines the water hammer stages associated with a pump trip, namely, the initial depressurisation, followed by air admission, then air expulsion, and finally the creation of a secondary pressure wave. For each air valve location and specific set of design conditions, the relationship between the transient magnitude and air valve outflow capacity is found to be non-linear, but to roughly follow the shape of a logistic curve having a lower left plateau for attenuated (type 1) behaviour and transitioning through type 2 behaviour to a higher right plateau for water-hammer-dominated (type 3) behaviour. Through an extensive set of simulations covering a wide range of conditions, the study identifies the size of the critical outflow orifices associated with both type 1 and type 3 responses and assesses the influence of the location of the air valve on the transient magnitude and on the timing of air pocket collapse. Furthermore, the paper highlights that a non-slam air valve is capable of effectively mitigating transient magnitudes provided that its design parameters are judiciously chosen and account for both the system’s attributes and the characteristics of the transient event.

The use of strain-gauge plethysmography in the functional assessment of chronic venous disease: five-year experience at a single centre.

Plethysmography can be used in the diagnosis and evaluation of chronic venous disease in the lower extremities. This study aimed to evaluate the applicability and reliability of strain-gauge plethysmography (SDP) in the functional assessment of chronic venous disease. This descriptive study was conducted between 2016 and 2021 at a single centre. Four hundred and thirty-two patients with symptomatic chronic venous disease were included in the study. All participants were diagnosed initially with Doppler ultrasonography. SGP was then performed to evaluate venous outflow capacity, venous reflux and muscle pump function. The average age was 45.16 ± 12.54 years (median age 46 years; range 20-78 years), and 239 (55.3%) women and 193 (44.7%) men were included in the study. The age groups, diagnosis, pathological distribution and risk factors were quantitatively determined according to gender. Localisation and lateralisation statistics of the pathologies are given. SGP measurements, including venous volume (V), venous emptying (VE), expelled volume ratio in four seconds (EV4/V), half refilling time (t½) and refilling volume (RV) of each lower extremity, were done individually to compare the involved extremity with the normal contralateral side. SGP measurements of each affected lower limb were also compared separately by gender, age group and disease onset. The correlation between t½ values and skin discolouration or oedema of the affected limb was examined. Finally, receiver operating characteristic curve analyses of the V, VE, EV4/V, t½ and RV values were done, and the cut-off values of each parameter were defined accordingly. High reliability and consistent results indicate that SGP is a practical and sensitive test for quantitative functional assessment of patients with chronic venous disease. It can be used as an effective method in diagnosing and following up chronic venous disorders. As there are no currently accepted cut-off values, we suggest that ours can be used as new reference values for SGP measurements.

Hydraulic Characteristics and Numerical Simulation of the Entrance Section of Ladder-Shaped Spillway

The ladder-shaped spillway in a certain reservoir junction is set as the engineering background in the paper. The hydraulic similarly model experiment and three-dimensional numerical simulation of hydraulic characteristics of water flow are performed. The outflow capacity, flow state analysis, velocity distribution, water surface line, pressure, and the energy dissipation rate are analyzed, and experimental results are compared with the numerical results. The conclusions demonstrate that the numerical results of the flow characteristics are very proximate to actual experimental results, the changeable law is the same, and their energy dissipation rate is basically consistent; it shows the feasibility of three-dimensional numerical simulation; the conclusions can provide the basis for the optimization about the flow state of the ladder-shaped spillway in the future.

Routes to Improve Arteriovenous Fistula Formation for Haemodialysis

Background. Contemporary methods to create primary arteriovenous fistula (AVF) for permanent vascular access (PVA) in haemodialysis continue to improve. The modified Brescia-Cimino operation is considered the main technique of forming native AVF. Various early PVA complications occur in 6–40 % patients entailing repeated surgical interventions.Materials and methods. The study was conducted at the vascular surgery unit of City Clinical Hospital No. 21 of Ufa. All patients had surgery for distal AVF formation in forearm. Native forearm AVF creation was aided by the hydraulic balloon dilation technique prior to forming anastomosis.Results. The PVA survival was 75.0 (n = 30), the median survival time corresponding to estimated time-to-rehospitalisation in at least 50 % patients (n = 30) was 4.0 ± 0.89 (95 % CI: 2.25–5.75) months. Mean time-to-relapse was 6.05 ± 1.15 (95 % CI: 3.8–8.3) months.Discussion. The results obtained suggest the accessory hydraulic balloon dilation method useful prior to forming anastomosis to provide for the vein mechanical expansion, outflow capacity assessment and prevent venous torsion at preparation steps. Preparing a certain vein length (10 cm) with ligation of putative tributaries is also of importance.Conclusion. The accessory technique of hydraulic balloon dilation of recipient vein in primary native AVF creation allows an intraoperative estimation of the vein state to exclude torsion and perform its mechanical dilation prior to forming anastomosis, which reduces the risk of postoperative thromboses.

Energy Dissipation in Stilling Basins with Side Jets from Highly Convergent Chutes

Spillways with Highly Converging Chutes (HCCs) are a non-conventional alternative that can be applied to achieve a higher outflow capacity when the weir length exceeds the width of the valley at the toe of gravity or arch dams. This kind of spillway has been used in the past, but no general studies have yet been published. This article summarizes experimental research work aiming to increase the knowledge of the effect of some design parameters of HCCs on the energy dissipation in the stilling basin at the toe of the dam. As a comparison reference, we use the Type I stilling basins, widely known by the technical dam engineering community. The obtained results show that spillways with HCCs are a promising alternative to traditional designs, combining the ability to increase the weir length with a high capacity to dissipate energy through the impingement effect of the frontal and the side jets inside the stilling basin.

Extended geographic information monitoring of urban ecotone based on cell transmission model

The road traffic network in the urban interlaced zone is a collection of road sections and nodes. The difficulty in road traffic monitoring lies in the processing of traffic at the node locations. In this paper, the cell transmission model is used to monitor the extended geographical information of the urban interlaced zone. Using the cell transmission model, the channelisation and cell outflow capacity at the intersection are calculated. According to the timing of traffic signals in the interlaced zone, calculations are made on the road traffic volume and accurately monitoring the vehicle density. The simulation experiment results show that the model in this paper can accurately monitor the congestion information of the gradation road network and the uniform road network in the urban interlaced zone traffic network, and the monitoring results are close to the actual results, indicating that the research method in this paper has stronger applicability.

Thermal waters of central Poland: a case study from Mogilno\u2013\u0141\xf3d\u017a Trough, Poland

Thermal waters in Poland occur in several different geothermal regions, but the best parameters for their effective utilisation are connected i.a. with the area of Polish Lowlands. One of the most prospective areas in the central part of Polish Lowlands for managing geothermal waters for various purposes is the area of Mogilno–Łódź Trough. There are currently 2 operating geothermal heating plants and several others in various stages of development. In this area, water with a temperature of 97.5 °C has been documented. The aim of this article is to determine and visualise the potential of geothermal waters of the central Poland (Mogilno–Łódź Trough) by providing the most important, potential geothermal water parameters. It is done by providing maps of potential temperature, mineralization, water outflow capacity, thermal power and physicochemical analysis (mineralization, waters type). The two most prospective geothermal reservoirs—Lower Jurassic and Lower Cretaceous—were analysed. The results of the studies indicate that this area is characterised by very favourable hydrogeological conditions. Geothermal energy utilisation should be connected with Lower Jurassic and Lower Cretaceous reservoirs, but it should be emphasised that a larger energy potential relates to waters from Lower Jurassic reservoir; however, they are characterised by high water mineralisation (up to 170 g/L). Waters of Lower Cretaceous reservoir are characterised by not only lower mineralisation (up to 100 g/L), but also lower temperature (max. 75 °C). The highest temperatures in the Lower Jurassic are recorded in the axial part of the Trough, where, locally, they exceed in the top of formation 100 °C. On the other hand, in edge Trough zones, water temperatures are 30–40 °C. The actual geothermal potential of the area is much higher than currently used. For example, potential discharge of wells is to over 400 m3/h in the Lower Cretaceous and up to over 500 m3/h in the Lower Jurassic.

Fluid outflow in the rat spinal cord: the role of perivascular and paravascular pathways

BackgroundCerebrospinal fluid (CSF) is thought to flow into the brain via perivascular spaces around arteries, where it mixes with interstitial fluid. The precise details concerning fluid outflow remain controversial. Although fluid dynamics have been studied in the brain, little is known about spinal cord fluid inflow and outflow. Understanding the normal fluid physiology of the spinal cord may give insight into the pathogenesis of spinal cord oedema and CSF disorders such as syringomyelia. We therefore aimed to determine the fluid outflow pathways in the rat spinal cord.MethodsA fluorescent tracer, Alexa-Fluor®-647 Ovalbumin, was injected into the extracellular space of either the cervicothoracic lateral white matter or the grey matter in twenty-two Sprague–Dawley rats over 250 s. The rats were sacrificed at 20 or 60 min post injection. Spinal cord segments were sectioned and labelled with vascular antibodies for immunohistochemistry.ResultsFluorescent tracer was distributed over two to three spinal levels adjacent to the injection site. In grey matter injections, tracer spread radially into the white matter. In white matter injections, tracer was confined to and redistributed along the longitudinal axonal fibres. Tracer was conducted towards the pial and ependymal surfaces along vascular structures. There was accumulation of tracer around the adventitia of the intramedullary arteries, veins and capillaries, as well as the extramedullary vessels. A distinct layer of tracer was deposited in the internal basement membrane of the tunica media of arteries. In half the grey matter injections, tracer was detected in the central canal.ConclusionsThese results suggest that in the spinal cord interstitial fluid movement is modulated by tissue diffusivity of grey and white matter. The central canal, and the compartments around or within blood vessels appear to be dominant pathways for fluid drainage in these experiments. There may be regional variations in fluid outflow capacity due to vascular and other anatomical differences between the grey and white matter.

Dynamic traffic assignment in degradable networks: paradoxes and formulations with stochastic link transmission model

ABSTRACTThis paper proposes a simultaneous route and departure time choice (SRDTC) problem with fixed demand in a degradable transport network. In this network, travelers face with stochastic travel times. Their selection of routes and departure times follows the UE principle in terms of the mean generalized route cost, which is defined as the probabilistic dynamic user optimal (PDUO) principle. The proposed PDUO-SRDTC problem is formulated as a variational inequality (VI) problem. As a special case of PDUO-SRDTC problem, the PDUO route choice (PDUO-RC) problem is also proposed and formulated as a VI problem. Network degradation is defined on the degradation of the outflow capacity of each link. A Monte Carlo-based stochastic link transmission model (MC-SLTM) is developed to capture the effect of physical queues and the random evolution of traffic states during flow propagation to estimate mean generalized route costs. Both the extragradient algorithm and the route-swapping method with a variable sample size scheme are developed to solve the proposed VI problems. Numerical examples are developed to illustrate the paradoxical phenomena of the problems and the effectiveness of the solution methods. Numerical results show that constructing a new road, enhancing link outflow capacity, or reducing outflow capacity degradation can lead to poor network performance and it is important to consider both network degradation and queue spillback when making transportation policies aimed at improving network performance. The results also demonstrate that the variable sample size scheme can give a quicker and better solution than the traditional fixed sample size scheme.

Imaging of the Intrascleral Aqueous Drainage System - New Insights for Glaucoma Surgery Targeting the Trabecular Meshwork

Numerous new techniques in glaucoma surgery target the trabecular meshwork, which is considered to be the main site of aqueous outflow resistance. These approaches rely on a functioning aqueous drainage system distal to the site of surgery. Thus, the intrascleral aqueous outflow tract comprises Schlemm's canal, collector channels and aqueous veins and has become an object of increasing research interest. The intrascleral outflow tract contributes approximately 25-50 % to the total aqueous outflow resistance, but the outflow capacity differs greatly over the segments of the eye. Morphological and functional assessment of the intrascleral outflow tract is challenging, due to its deep scleral location and the complex nature of its small diameter vessel network. In this review, we present novel insights into its morphology and function, based on advances in a variety of imaging modalities, including optical coherence tomography, fluorescence imaging and electron microscopy. Together with clinical data, they support the paradigm of significant sectorial differences in aqueous outflow, which has a direct impact on glaucoma surgery targeting sectors of the trabecular meshwork, such as trabeculectomy ab interno or trabecular meshwork bypass stents. Possible future applications of intrascleral outflow tract imaging are discussed.

Evaluation of potential risk factors for development of primary angle-closure glaucoma in Bouviers des Flandres.

OBJECTIVE To evaluate potential risk factors for development of primary angle-closure glaucoma (PACG) in Bouviers des Flandres. DESIGN Prospective, observational study. ANIMALS 98 Bouviers des Flandres. PROCEDURES All dogs underwent slit-lamp biomicroscopy, indirect ophthalmoscopy, gonioscopy, applanation tonometry, streak retinoscopy, and A-scan, B-scan, and high-resolution ultrasonography. Iridocorneal angles and degree of pectinate ligament dysplasia sheeting were graded, and an angle index was mathematically derived for each eye on the basis of these values. Ciliary clefts evaluated by high-resolution ultrasonography were classified as open, narrow, or closed. Owners were contacted by telephone 7 to 9 years after the initial examination to determine whether dogs had a subsequent diagnosis of PACG. Relationships between previously recorded variables and the development of PACG were evaluated by logistic regression methods. Available pedigrees were reviewed to assess genetic relationships among affected dogs. RESULTS 9 of 92 (9.8%) dogs with follow-up information available developed PACG. An angle index < 1 and presence of a narrow or closed ciliary cleft in 1 or both eyes were each significantly associated with development of PACG. Odds of developing PACG for dogs with an angle index < 1 (indicating marked reduction in outflow capacity through the iridocorneal angle), a narrow or closed ciliary cleft in > 1 eye, or both findings were 13, 20, and 28 times those for dogs that did not have these findings, respectively. All dogs that developed PACG shared 1 common male sire or grandsire. CONCLUSIONS AND CLINICAL RELEVANCE Several anatomic factors were significant risk factors for development of PACG in this population of dogs. Results also suggested a genetic component for the disease.

Comparison of static and dynamic resilience for a multipurpose reservoir operation

AbstractReliability, resilience, and vulnerability are the traditional risk measures used to assess the performance of a reservoir system. Among these measures, resilience is used to assess the ability of a reservoir system to recover from a failure event. However, the time‐independent static resilience does not consider the system characteristics, interaction of various individual components and does not provide much insight into reservoir performance from the beginning of the failure event until the full performance recovery. Knowledge of dynamic reservoir behavior under the disturbance offers opportunities for proactive and/or reactive adaptive response that can be selected to maximize reservoir resilience. A novel measure is required to provide insight into the dynamics of reservoir performance based on the reservoir system characteristics and its adaptive capacity. The reservoir system characteristics include, among others, reservoir storage curve, reservoir inflow, reservoir outflow capacity, and reservoir operating rules. The reservoir adaptive capacity can be expressed using various impacts of reservoir performance under the disturbance (like reservoir release for meeting a particular demand, socioeconomic consequences of reservoir performance, or resulting environmental state of the river upstream and downstream from the reservoir). Another way of expressing reservoir adaptive capacity to a disturbing event may include aggregated measures like reservoir robustness, redundancy, resourcefulness, and rapidity. A novel measure that combines reservoir performance and its adaptive capacity is proposed in this paper and named “dynamic resilience.” The paper also proposes a generic simulation methodology for quantifying reservoir resilience as a function of time. The proposed resilience measure is applied to a single multipurpose reservoir operation and tested for a set of failure scenarios. The dynamic behavior of reservoir resilience is captured using the system dynamics simulation approach, a feedback‐based object‐oriented method, very effective for modeling complex systems. The results of dynamic resilience are compared with the traditional performance measures in order to identify advantages of the proposed measure. The results confirm that the dynamic resilience is a powerful tool for selecting proactive and reactive adaptive response of a multipurpose reservoir to a disturbing event that cannot be achieved using traditional measures. The generic quantification approach proposed in the paper allows for easy use of dynamic resilience for planning and operations of various civil infrastructure systems.

An intersection-movement-based stochastic dynamic user optimal route choice model for assessing network performance

Different from traditional methods, this paper formulates the logit-based stochastic dynamic user optimal (SDUO) route choice problem as a fixed point (FP) problem in terms of intersection movement choice probabilities, which contain travelers’ route information so that the realistic effects of physical queues can be captured in the formulation when a physical-queue traffic flow model is adopted, and that route enumeration and column generation heuristics can be avoided in the solution procedure when efficient path sets are used. The choice probability can be either destination specific or origin–destination specific, resulting into two formulations. To capture the effect of physical queues in these FP formulations, the link transmission model is modified for the network loading and travel time determination. The self-regulated averaging method (SRAM) was adopted to solve the FP formulations. Numerical examples were developed to illustrate the properties of the problem and the effectiveness of the solution method. The proposed models were further used to evaluate the effect of information quality and road network improvement on the network performance in terms of total system travel time (TSTT) and the cost of total vehicle emissions (CTVE). Numerical results show that providing better information quality, enhancing link outflow capacity, or constructing a new road can lead to poor network performance.

Performance Measures for Optimizing Diverging Interchanges and Outcome Assessment with Drone Video

Diverging diamond interchanges (DDIs) are an emerging interchange configuration that eliminates the need for left-turn phases in conventional diamonds and may be less expensive to construct than some alternative geometries. This paper examines signal timing for DDIs. DDI signal timing typically has used a two-phase configuration that reflects the two competing movements at the crossover points at each inter section of the DDI. This configuration inherently contains some inefficiency: (a) there is potential for internal queuing under two-phase configuration and (b) it is possible for the inflow demand to exceed outflow capacity of the interchange. This paper uses high-resolution event data to develop performance measures for evaluating operations at a DDI in Salt Lake City, Utah. Alternatives to the existing signal timing within the two-phase configuration are modeled and tested with a field deployment. The field deployment demonstrated the ability to prioritize ramp or through vehicles within the two-phase configuration. Additionally, a new three-phase configuration was developed and deployed to address the internal queuing that occurs with two-phase timing. With this new configuration, the flows from one DDI intersection to the other are balanced, and progression within the DDI is improved. With the implementation of the three-phase configuration, the percentage of vehicles arriving on green at the heaviest internal movement within the DDI increased from 53% to 92%. To illustrate these performance measures and improved DDI operation qualitatively, a video from a tethered unmanned aerial vehicle demonstrated the vehicle arrival characteristics by overlaying vehicle detection and signal state graphics on the video.

Computerized Venous Strain-gauge Plethysmography is a Reliable Method for Measuring Venous Function

To achieve reference values for computerized strain-gauge plethysmography (SGP), to assess reproducibility, and to evaluate the influence of different factors such as age, gender, body mass index, and symptomatic post-thrombotic disease on commonly used variables. Sixty-three healthy controls and 56 patients with previous deep venous thrombosis (DVT) were included. All participants underwent computerized SGP with evaluation of outflow capacity, as well as evaluation of venous reflux and muscle pump function. All variables were significantly reduced in DVT limbs, both compared with contralateral limbs and with healthy controls. Only two patients had all values within normal ranges (=mean±2 SD in controls). Measures of outflow capacity had a coefficient of variation (CV) of 5-6% and exercise-induced volume changes a CV of 10-15%. In symptomatic post-thrombotic limbs half-refilling time was significantly related to presence of edema (R=-0.28, p<.05) and to chronic skin changes (R=-0.58, p<.001). We suggest that our values in healthy controls can be used as new reference values for computerized venous strain-gauge plethysmography. The computerized design ensures high reproducibility and the results indicate that this is a very useful and sensitive test for functional quantitative assessment of patients with venous disease.

Placement of an arterial hepatic catheter after a major hepatectomy for colorectal liver metastases: Is this safe?

Studies have suggested that hepatic arterial infusion of chemotherapy (HAI) after resection of colorectal liver metastasis (CRLM) may improve patient's survival. The placement of a catheter in the hepatic artery at the time of hepatic surgery should therefore be considered in patients at high risk of hepatic recurrence. The aim of this study was to compare post-operative outcomes in patients who underwent at least a major hepatectomy (≥3 segments) for CRLM with or without catheter placement. From 2000 to 2010, 57 patients who underwent at least a major hepatectomy for CRLM resection were selected from a prospective database. Among them, 22 had had a catheter insertion during surgery. The two groups were similar in terms of age, body mass index (BMI), ASA score, and the average number of pre-operative courses of systemic chemotherapy (11±5). The rate of overall complications was slightly higher after catheter insertion (63% vs. 51%) although not significant (p=0.36). Two patients had died post-operatively from liver insufficiency; both had undergone catheter insertion after a major hepatectomy associated with contralateral procedures resulting in a small remnant liver volume with low outflow capacity. Thrombosis of the common hepatic artery and portal venous gas were depicted on both CT scan. Although the placement of an arterial catheter during a major hepatectomy does not significantly increase the rate of postoperative complications two patients died post-operatively in this study from vascular thrombosis. In case of extended and complex hepatectomy, with a higher risk of post-operative complications, delaying the catheter placement could be recommended.

Modulation of graft vascular inflow guided by flowmetry and manometry in liver transplantation

Survival of the partial graft after living donor liver transplantation owes much to its tremendous regenerative ability. With excellent venous outflow capacity, a graft within a wide range of graft-to-standard-liver-volume ratios can cope with portal hypertension that is common in liver transplant recipients. However, when the ratio range is exceeded, modulation of graft vascular inflow becomes necessary for graft survival. The interplay between graft-to-standard-liver-volume ratio and portal pressure, in the presence of portosystemic shunt or otherwise, requires individualized modulation of graft portal and arterial inflows. Boosting of portal inflow by shunt ligation can be guided by transonic flowmetry, whereas muting of portal inflow by splenic artery ligation can be monitored by portal electronic manometry. We describe four cases to illustrate the above. One patient had hepatic artery thrombosis resulting from splenic artery steal syndrome which was the sequela of small-for-size syndrome. Emergency splenic artery ligation and re-anastomosis of the hepatic artery successfully muted the portal inflow and boosted the hepatic arterial inflow. Another patient with portal vein thrombosis underwent thrombendvenectomy. Portal inflow was boosted with ligation of portosystemic shunt, which is often present in these patients with portal hypertension. The coexistence of splenic aneurysm and splenorenal shunt required ligation of both in the third patient. The fourth patient, with portal pressure and flow monitoring, avoided ligation of a coronary vein which became a main portal inflow after portal thrombendvenectomy. Management of graft inflow modulation guided selectively by transonic flowmetry or portal manometry was described.

Risk Factors of SFSS in Adult-to-Adult Living Donor Liver Transplantation Using the Right Liver: A Single-Center Analysis of 217 Cases

Small-for-size Syndrome (SFSS) in adult-adult living right lobe liver transplantation (A-ALRLT) remains the greatest limiting factor for the expansion of using segmental liver transplantation and the major cause of worse short-term prognoses after LDLT. The causes of SFSS are not clear, so in this study we approached the risk factors of the SFSS. The study included 217 consecutive adult recipients that underwent living right lobe liver transplantation at our center. Cases were divided into two groups: 45 cases were determined as SFSS and 172 cases without SFSS within one month after transplantation. Preoperative factors like donor and recipient characteristics, operational data and postoperative factors were compared between the two groups. Factors possibly related to postoperative SFSS were also analyzed using logistic regression. After comparing the two groups, there was no significant difference in donor and recipient background characteristics and no differences were found between the two groups, except for portal inflow volume and MELD score which were much higher and GRWR and outflow volume were much lower in G1. Logistic regression analysis revealed four independent factors associated with SFSS development in right lobe graft: GRWR, MELD score, portal inflow volume and outflow capacity. Small GRWR, high MELD score, high portal inflow volume and low outflow capacity are four risk factors in A-ALRLT.