Filter Lifetime Research Articles

Sulfonated Pentablock Copolymer (NexarTM) for Water Remediation and Other Applications.

This review focuses on the use of a sulfonated pentablock copolymer commercialized as NexarTM in water purification applications. The properties and the use of sulfonated copolymers, in general, and of NexarTM, in particular, are described within a brief reference focusing on the problem of different water contaminants, purification technologies, and the use of nanomaterials and nanocomposites for water treatment. In addition to desalination and pervaporation processes, adsorption and photocatalytic processes are also considered here. The reported results confirm the possibility of using NexarTM as a matrix for embedded nanoparticles, exploiting their performance in adsorption and photocatalytic processes and preventing their dispersion in the environment. Furthermore, the reported antimicrobial and antibiofouling properties of NexarTM make it a promising material for achieving active coatings that are able to enhance commercial filter lifetime and performance. The coated filters show selective and efficient removal of cationic contaminants in filtration processes, which is not observed with a bare commercial filter. The UV surface treatment and/or the addition of nanostructures such as graphene oxide (GO) flakes confer NexarTM with coating additional functionalities and activity. Finally, other application fields of this polymer are reported, i.e., energy and/or gas separation, suggesting its possible use as an efficient and economical alternative to the more well-known Nafion polymer.

A novel pulse-jet cleaning method to effectively extend the lifetime of pleated filter and reduce dust emission

To solve the problem of poor cleaning effect of pleated filter, this study explored in detail the impact of various cleaning method on the filtration and cleaning performance of the filter media in clean-on-demand mode. Furthermore, the clogging mechanism of the filter and the deposition structure of dust on the filter media were analyzed based on the effective filtration area ratio and true resistance coefficient calculated by the proposed model. The results demonstrated that for the constant pulse-jet cleaning pressure (PJCP), increasing PJCP was more conducive to removing dust deposited on the filter media and improving regeneration efficiency, although higher PJCP increased power consumption. Different from the thick primary dust layer formed on the filter surface under the constant PJCP of 0.3 MPa, the dust was mainly deposited inside the filter media under the constant PJCP of 0.5 and 0.7 MPa. In contrast, stepwise increasing PJCP was more effective in cleaning and regenerating the filter media, which was reflected in further extending the filter lifetime, increasing the processing air volume and reducing the dust emission concentration with acceptable energy consumption. Moreover, the filter media mainly clogged itself and formed a medium thickness primary dust layer on the filter surface.

Kidney replacement and conservative therapies in rhabdomyolysis: a retrospective analysis

BackgroundToxic renal effects of myoglobin following rhabdomyolysis can cause acute kidney injury (AKI) with the necessity of kidney replacement therapy (KRT). Fast elimination of myoglobin seems notable to save kidney function and intensify kidney repair. Clinical data regarding efficacy of KRT in critical care patients with rhabdomyolysis and AKI are limited. This retrospective analysis aimed to identify differences between conservative therapy and different modalities of KRT regarding myoglobin elimination and clinical outcome.MethodsThis systematic, retrospective, single-center study analyzed 328 critical care patients with rhabdomyolysis (myoglobin > 1000 µg/l). Median reduction rate of myoglobin after starting KRT was calculated and compared for different modalities. Multivariate logistic regression models were established to identify potential confounder on hospital mortality. Filter lifetime of the various extracorporeal circuits was analyzed by Kaplan–Meier curves.ResultsFrom 328 included patients 171 required KRT. Health condition at admission of this group was more critical compared to patient with conservative therapy. Myoglobin reduction rate did not differ between the groups (KRT 49% [30.8%; 72.2%] vs. conservative treatment (CT) 61% [38.5%; 73.5%]; p = 0.082). Comparison between various extracorporeal procedures concerning mortality showed no significant differences. Hospital mortality was 55.6% among patients with KRT and 18.5% with CT (p < 0.001). Multivariate logistic regression model identified requirement for KRT (OR: 2.163; CI: 1.061–4.407); p = 0.034) and the SOFA Score (OR: 1.111; CI: 1.004–1.228; p = 0.041) as independent predictive factors for hospital mortality. When comparing specific KRT using multivariate regression, no benefit was demonstrated for any treatment modality. Life span of the extracorporeal circuit was shorter with CVVH compared to that of others (log-Rank p = 0.017).ConclusionsThis study emphasizes that AKI requiring KRT following rhabdomyolysis is accompanied by high mortality rate. Differences in myoglobin reduction rate between various KRTs could not be confirmed, but CVVH was associated with reduced filter lifetime compared to other KRTs, which enable myoglobin elimination, too.Graphical

High-fidelity 3D simulation of dust-loading behavior and clogging process of coarse nonwoven filter media considering collision effect

The filter lifetime of fibrous media is important for the energy-saving application of air filters and efficient delivery of clean air. The clogging process significantly affects the dust-loading behavior of fibrous filter media. Therefore, an effective methodology for determining the deposition of dust particles inside filter structures is necessary. This study conducted numerical dust loading simulations on a three-dimensional (3D) X-ray tomographic structure of coarse nonwoven filter media. Spherical particles with a density of 1808 kg/m3 were used in the simulations instead of plate-like dust particles with a higher silica density. A high-fidelity simulation model was successfully developed by considering collision effects. Key factors were determined, including the Hamaker constant for the adhesion energy, restitution coefficient for the particle kinetic energy, and sliding motion. Remarkably, the deviation between the simulated and experimental dust holding capacity was less than 1 %. The developed simulation model enabled a quantitative evaluation of the clogging process and 3D in-situ evolution of particle deposition and pore structures. It was observed that 95.6 % of the maximum deposited dust mass within the fibrous structure was captured at the clogging point. Several computational methods yielded accurate pore size evaluations and clear 3D pore structure visualizations. The developed methodology for high-fidelity simulation and 3D analysis can be further applied to other two-phase filtration and separation fields, including aerosol filtration, coalescence filtration, membrane fouling, micro/nanoplastic capture, and oil/water separation.

A simplified protocol of regional citrate anticoagulation with phosphate-containing solutions in infants and children treated with continuous kidney replacement therapy.

Regional citrate anticoagulation (RCA) is the preferred modality of anticoagulation used in continuous kidney replacement therapy (CKRT) in adults and less extensively in children. Potential metabolic complications limit widespread use in infants, neonates, and in children with liver failure. We report our experience with a simplified protocol in 50 critically ill children, infants, and neonates, some of them with liver failure, with commercially available solutions containing phosphorous and higher concentration of potassium and magnesium. RCA allowed attainment of a mean filter lifetime of 54.5 ± 18.2h, 42.5% of circuits lasted more than 70h, and scheduled change was the most frequent cause of CKRT interruption. Patient Ca++ and circuit Ca++ were maintained in the target range with mean values of 1.15 ± 0.13mmol/l and 0.38 ± 0.07mmol/l, respectively. No session had to be stopped because of metabolic complications. The most frequent complications were hyponatremia, hypomagnesemia, and metabolic acidosis mostly related to primary disease and critical illness. No session had to be stopped because of citrate accumulation (CA). Transitory CA occurred in 6 patients and was managed without requiring RCA interruption. No patients with liver failure presented CA episodes. In our experience, RCA with commercially available solutions was easily applied and managed in critically ill children, even in patients with low weight or with liver failure. Solutions containing phosphate and higher concentrations of magnesium and potassium allowed reduction of metabolic derangement during CKRT. Prolonged filter life was ensured with no detrimental effects on patients and reduced staff workload. A higher resolution version of the Graphical abstract is available as Supplementary information.

Sustainable and Optimized Harmonic Filter Design for Industrial Loads

Over the past two decades, there has been a surge in digitalization across industries. This tremendous growth of industries has brought many challenges in the field of semiconductor technologies for controlling non-linear loads, resulting in distorted voltages, currents, and power factor, which frequently disturb other loads that are connected in parallel. Many types of passive filters have been designed by power engineers to moderate or reduce the degree of harmonic content in the system; nevertheless, manual tuning is required, which takes time and energy. To lower Total Harmonic Distortion %THD, optimization technique approaches play an important role in tuning the filter components as well as the Quality Factor, increasing the filter's lifetime, and confirming compliance with standards. The Particle Swarm Optimization is proposed for non-linear AHUs, Un-Interrupted Power Supply, and Lighting loads from the IT industry, each with a different dominant harmonic. This paper presents the passive filters for the dominant harmonic which were simulated using MATLAB Simulink software, as well as the accompanying waveforms and findings.

Analysis of Air Supply Air Flow Rate Decrease by Accelerated Dust Load Experiments on Heat-Recovery Ventilator Air Filter

Purpose: Recently, owing to the high concentration of fine dust, air filters have become essential in heat-recovery ventilators. In Korea, air filter performance is evaluated by the standard, “KS B 6141 Air Filter Units for Ventilation.” However, filter lifetime has not been examined. In this study, an accelerated test method for air filters was developed. In addition, the change in the supply air flow rate was analyzed under filter conditions. Method: The filter accelerated test conditions were identified, and the annual average concentration of fine dust in the atmosphere was determined. A vertical wind tunnel was built to evaluate the air filter lifetime. The ISO A2 dust was dosed to an air filter. In addition, the supply air flow rates were measured for the three products that the accelerated air filter used. Result: Under the lab test conditions, the supply air flow rate changed with the filter usage time and the air resistance. In the experiments, only ISO A2 dust was used. Subsequently, the effects of various particles were tested on the development of the acceleration test method for filters.

Smoke and dust‐free laser use

Abstract“The filter lifetimes have increased enormously. For us, this means greatly reduced effort and, most importantly, costs,” says Olaf Lehmann, head of production at Werba Plast.

Bioaugmentation of Biological Activated Carbon Filters for Enhanced Micropollutant Removal

Granular activated carbon (GAC) filtration is an important technology for micropollutant removal from water. In GAC filters, micropollutants adsorb onto the activated carbon and can also be biodegraded, prolonging the filter lifetime. Biodegradation can be enhanced by introducing micropollutants degrading microorganisms to the filters, that is, through bioaugmentation. We assessed pyrazole adsorption to activated carbon and biodegradation in GAC filters inoculated with pyrazole degrading biomass originating from a drinking water plant. Pyrazole was chosen as a model micropollutant because it was detected at high levels in 2015 in Dutch surface water, and little is known about its removal mechanism in water treatment. GAC filters without inoculation and inoculated at different moments were operated, and breakthrough curves were fit to an adsorption and biodegradation model based on surface diffusion and Monod kinetics. Pyrazole biodegradation was successfully transferred from a sand filter to GAC filters and contributed to decreasing pyrazole concentrations below 10 μg/L in the GAC filter effluent. Pyrazole degradation was a stable process that could be maintained despite the lack of pyrazole in the filter influent for up to 30 days. Achieving a combination of adsorption and biodegradation in GAC filters is essential to sustain high micropollutant removals in the long term.

Performance evaluation of activated carbon sorbents for indoor air purification during normal and wildfire events.

Volatile organic compounds (VOCs) are a significant class of indoor air pollutants and are known for their adverse effects on health. A common strategy to reduce indoor VOC levels is to use sorbents, including activated carbons (ACs). The amount of activated carbon is critical to achieving a reasonable AC filter lifetime in an air purification device. The study aims to estimate the amount of carbon needed in a typical indoor environment and in a heavy use setting such as during cooking, agriculture field fires, or wildfires. The problem is complex as various types of ACs are used, and the type and concentration of VOCs in the indoor environment also vary in different settings. Therefore, literature data on thermophysical parameters for 45AC-VOC pairs was used to estimate the required amount of AC under a given set of conditions. The study uses modeling distributions of the footprint of suitable carbon filters for the removal of common VOCs encountered indoors for a period of 30 days. It was found that while 50% of AC-VOC pairs surveyed will require about 190-370g at low indoor VOCs levels of 0.1-1μmol/m3(considered a good clean indoor environment), up to 1.1kg of ACs are needed for a carbon filter to survive 30 days in a typical indoor environment (VOCs levels of 10μmol/m3). On the other hand, 3-15kg or more AC will be needed in a filter to survive 30 days during adverse events such as wildfires. The objective of the present study is to aid consumers and businesses in making an informed decision on the type of AC-based indoor air filters that meet their needs. Using this data, an open-access online calculator is being developed to predict the amount of carbon needed in a filter/device at any specific indoor air condition.

A Graphical Representation of Membrane Filtration

We analyze the performance of membrane filters represented by pore networks using two criteria: (1) total volumetric throughput of filtrate over the filter lifetime and (2) accumulated foulant concentration in the filtrate. We first formulate the governing equations of fluid flow on a general network, and we model transport and adsorption of particles (foulants) within the network by imposing an advection equation with a sink term on each pore (edge) as well as conservation of fluid and foulant volumetric flow rates at each pore junction (network vertex). Such a setup yields a system of partial differential equations on the network. We study the influence of three geometric network parameters on filter performance: (1) average number of neighbors of each vertex, (2) initial total void volume of the pore network, and (3) tortuosity of the network. We find that total volumetric throughput depends more strongly on the initial void volume than on average number of neighbors. Tortuosity, however, turns out to be a universal parameter, leading to almost perfect collapse of all results for a variety of different network architectures. In particular, the accumulated foulant concentration in the filtrate shows an exponential decay as tortuosity increases.

MO272: Effect of the Hollow Fiber Diameter and Membrane Surface Area of the Polymethyl Methacrylate Membrane Filter Used in Continuous Renal Replacement Therapy on the Lifetime of the Filter

Abstract BACKGROUND AND AIMS When polymethyl methacrylate (PMMA) membranes are used in renal replacement therapy, inflammatory cytokines and other substances are removed by adsorption. However, these filters are also prone to clogging and the filter lifetimes are likely to be short. In the present study, we investigated the effects of the hollow fiber inner diameter and membrane area of PMMA membranes on the filter lifetime and protein removal performance using an in vitro continuous hemofiltration (CHF) experimental model with porcine blood. METHOD Three filters with different hollow fiber inner diameters and membrane areas were used: CH-1.0N (membrane area, 1.0 m2; hollow fiber inner diameter, 200 µm), CH-1.0W (prototype: 1.0 m2; 240 µm), and CH-1.8W (1.8 m2; 240 µm). Blood samples from one pig were divided into three portions, and in vitro CHF experiments for each filter were performed at QB = 100 mL/min and QS = QF = 10 mL/min. The pressure changes, total protein concentration in the blood, and total protein amount in the filtrate were measured during the experiments. From the results of the pressure changes, the time for the TMP to reach 200 mmHg (corresponding to the time when the membrane pores were clogged) and the time for the pressure drop through the filter to reach 200 mmHg (corresponding to the time when the hollow fibers were clogged) were calculated as the filter lifetime for comparative evaluation. RESULTS The time for the TMP to reach 200 mmHg was significantly longer with CH-1.8W than that with CH-1.0N or CH-1.0W (Friedman test, P &amp;lt; .05, n = 15). The time for the pressure drop through the filter to reach 200 mmHg was significantly longer with CH-1.8W than that with CH-1.0N or CH-1.0W (Friedman test, P &amp;lt; 0.05, n = 15). The results suggest that an increased membrane surface area is an essential factor for extending the filter lifetime. The total protein adsorption was significantly higher for the CH-1.0W and CH-1.8W filters than for the CH-1.0N filter (two-way ANOVA and post hoc Tukey test, P &amp;lt; 0.01, n = 15). Thus, the membranes with larger hollow fiber inner diameters (CH-1.8W and CH-1.0W) adsorbed more protein. CONCLUSION A larger membrane area contributes to a longer filter lifetime, whereas increase in the hollow fiber inner diameter does not. On the other hand, the protein removal performance, especially the adsorption performance, was higher for membranes with larger hollow fiber inner diameters.

Radiological HEPA Filter 10-year Lifetime Evaluation in Research Facilities.

High-efficiency particulate air (HEPA) filters are widely employed by nuclear facilities to remove radiological particulate matter from their effluent exhaust streams. The purpose of this study is to evaluate the relationships between the 10-y HEPA filter lifetime deployment and its other performance indicators. This 10-y-long endeavor to collect and analyze data regarding the service life of HEPA filters at the Pacific Northwest National Laboratory began in 2010. A set of HEPA filters was selected, and the filters have been surveyed and analyzed at least annually to verify compliance with permit conditions. The study suggests the frequency of filter replacement should be based on the actual operational requirements, such as fume hood face velocity and/or efficiency test results, instead of on the prescribed filter "age limit" of 10 y from the date of manufacture (e.g., birth date) when operating under dry conditions. The study has now been completed, and over the past decade, all the HEPA filters have been replaced due to either technical issues as listed in this report or the previously recommended filter "age limit" of 10 y as prescribed by the oversight bodies. Experimentally determined failure rates are also determined from the data set and can be used to estimate the chances of HEPA filters surviving 15, 20, or even 30 y.

Comparison of Clinical Outcomes of Different Connection Modes of Extracorporeal Membrane Oxygenation Combine with Continuous Renal Replacement Therapy

To evaluate the effect of different connection modes of ECMO and CRRT on patients with acute kidney injury (AKI). Twenty-one patients received ECMO with AKI. These patients were admitted to our center from December 2018 to February 2021, selected, and treated with both ECMO and CRRT. They were divided into A connection mode (pre-membrane-pre-pump connection) and B connection mode (post-membrane-post-pump connection). We compared clinical indicators and outcomes between two connection modes. There were eight cases (38.91%) in A connection mode and 13 cases (61.09%) in B connection mode, with median durations of ECMO assistance of 5 days and 7 days, respectively. Median flow rates of ECMO of 3.0 L/min and 2.5 L/min, respectively; CRRT flow rates of 200 mL/min and 180 mL/min, respectively. CRRT filter lifetime was over 48h in both connection modes. Except for NT-pro BNP, no significant differences in clinical indicators were observed between the two groups before or after the treatment (P > .05). Both connection modes could achieve the therapeutic purpose and need no higher level of anticoagulation for patients simultaneously treated with ECMO and CRRT. Two modes had no impact on treatment effect and clinical indicators in patients. It had no effect on length of ICU stay and prognostic.

Recurrent Early Filter Clotting during Continuous Veno-Venous Hemodialysis with Regional Citrate Anticoagulation is Linked to Systemic Thrombin Generation and Heparin Induced Thrombocytopenia Type II: A Retrospective Analysis

Objective: Regional Citrate Anticoagulation (RCA) for Continuous Renal Replacement Therapy (CRRT) is widely used and leads to an excellent clottingfree filter survival. Despite strict adherence to protocols, in some cases recurrent early filter-clotting occurs. The aim of this observational study was to evaluate the underlying causes and the efficacy of interventions in patients with early recurrent filter-clotting during RCA. Methods: In a retrospective analysis of a cohort of 1183 patients treated with RCA-CRRT we detected 12 patients with early filter-clotting unrelated to protocol violation or any obvious technical or medical reason. Results: All patients were systemically anticoagulated with low molecular weight or unfractionated heparin for at least 24h before initiation of Continuous Veno-Venous Hemodialysis with RCA (RCA-CVVHD). During RCA, all postfilter ionized calcium concentrations were in the target range (mean 0.33±0.05 mmol/L). At the time of the first clotting event, thrombocyte counts were 168±66/ nL. After the clotting events, the systemic anticoagulation was switched to argatroban in all patients. With systemic anticoagulation using argatroban filter lifetime of RCA-CVVHD increased significantly (p&lt;0.001) and clotting-events decreased from 0.61 to 0.10 per 24h. All patients were tested for HIT and 5/12 (42%) had a positive test for hep-PF4-antibodies. Application of argatroban significantly reduced early filter-clotting both in HIT-positive patients as well as in HIT-negative patients. At the time of the first clotting event, no patient had clinical signs of thrombosis or thromboembolism. However, during follow up a thromboembolic event occurred in three patients. Conclusion: In patients with recurrent early filter-clotting despite strict adherence to the citrate protocol undetected HIT or other causes of thrombin activation may be present. Therefore, patients with recurrent early filter clotting in RCA-CVVHD should be screened for HIT or other conditions that may activate thrombin. A significant improvement of filter run-time can be achieved by systemic administration of a thrombin inhibitor both in patients with and without HIT.

Recurrent Early Filter Clotting during Continuous Veno-Venous Hemodialysis with Regional Citrate Anticoagulation is Linked to Systemic Thrombin Generation and Heparin Induced Thrombocytopenia Type II: A Retrospective Analysis

Objective: Regional Citrate Anticoagulation (RCA) for Continuous Renal Replacement Therapy (CRRT) is widely used and leads to an excellent clottingfree filter survival. Despite strict adherence to protocols, in some cases recurrent early filter-clotting occurs. The aim of this observational study was to evaluate the underlying causes and the efficacy of interventions in patients with early recurrent filter-clotting during RCA. Methods: In a retrospective analysis of a cohort of 1183 patients treated with RCA-CRRT we detected 12 patients with early filter-clotting unrelated to protocol violation or any obvious technical or medical reason. Results: All patients were systemically anticoagulated with low molecular weight or unfractionated heparin for at least 24h before initiation of Continuous Veno-Venous Hemodialysis with RCA (RCA-CVVHD). During RCA, all postfilter ionized calcium concentrations were in the target range (mean 0.33±0.05 mmol/L). At the time of the first clotting event, thrombocyte counts were 168±66/ nL. After the clotting events, the systemic anticoagulation was switched to argatroban in all patients. With systemic anticoagulation using argatroban filter lifetime of RCA-CVVHD increased significantly (p&lt;0.001) and clotting-events decreased from 0.61 to 0.10 per 24h. All patients were tested for HIT and 5/12 (42%) had a positive test for hep-PF4-antibodies. Application of argatroban significantly reduced early filter-clotting both in HIT-positive patients as well as in HIT-negative patients. At the time of the first clotting event, no patient had clinical signs of thrombosis or thromboembolism. However, during follow up a thromboembolic event occurred in three patients. Conclusion: In patients with recurrent early filter-clotting despite strict adherence to the citrate protocol undetected HIT or other causes of thrombin activation may be present. Therefore, patients with recurrent early filter clotting in RCA-CVVHD should be screened for HIT or other conditions that may activate thrombin. A significant improvement of filter run-time can be achieved by systemic administration of a thrombin inhibitor both in patients with and without HIT.

Hepa filter age evaluation and estimate of nominal lifetime in nuclear facilities

In 2020, PNNL completed a literature search for high-efficiency particulate air (HEPA) filter age information. HEPA filters are used in many operations to remove particulate matter from effluent exhaust streams. They are thought to degrade over time both during proper storage and during normal operational service; however, the rate at which the filters degrade remains unknown. This brings into question if age is an adequate indicator of HEPA filter performance. Data from six previous reports were obtained from the literature search and combined to create a data set of 1600 operating filters. Filter usage was identified from multiple facilities. The various types of filters (e.g., axial flow, self-contained, and standard 61 × 61 × 28 cm; and both separator and separatorless) reported were constructed to the requirements Section FC (HEPA Filters) or Section FK (Special HEPA Filters) of the American Society of Mechanical Engineers AG-1 code. Filters were presumed to have continuously met the operational criteria and in particular passed both annual efficiency tests and annual differential pressure measurements. The environmental conditions within the exhaust system were also assumed adequate for long-term filter operation. The data, by the nature of the reports, excludes rejected filters from quality assurance evaluations, intake, or installation testing. The collective data set shows over half of were operating past the recommended 10-year Department of Energy (DOE) lifetime. Data was evaluated for age lifetime using a linear trendline, survival function, probability functions, and failure rate; financial impacts were also addressed. This report supports the notion that HEPA filters can operate safely and efficiently under proper maintenance well past the 10-year lifetime established by DOE. Using the results of the four age evaluation approaches, they collectively point to the reasonableness of an operating HEPA filter lifetime of 20 years. The results are not necessarily definitive, but nevertheless, they are promising. The analysis provides reasonable assurance that when implemented using a graded approach with well-defined performance and operational requirements, extending the service life for HEPA filters beyond 10 years is low risk.

On the performance of multilayered membrane filters

Multilayered membrane filters, which consist of a stack of thin porous membranes with different properties (such as pore size and void fraction), are widely used in industrial applications to remove contaminants and undesired impurities (particles) from a solvent. It has been experimentally observed that the performance of well-designed multilayer structured membranes is markedly better than that of equivalent homogeneous membranes. Mathematical characterization and modeling of multilayered membranes can help our understanding of how the properties of each layer affect the performance of the overall membrane stack. In this paper, we present a simplified mathematical model to describe how the pore-scale properties of a multilayered membrane affect the overall filter performance. Our results show that, for membrane stacks where the initial layer porosity decreases with depth, larger (negative) porosity gradients within a filter membrane are favorable for increasing throughput and filter lifetime, but at the expense of moderately poorer initial particle retention. We also found that the optimal layer thickness distribution that maximizes total throughput corresponds to a membrane stack with larger (negative) porosity gradients in which layer thickness increases slightly between successive layers in the depth of the membrane.

Filter lifetimes of different hemodiafiltration membrane materials in dogs: reevaluation of the optimal anticoagulant dosage

BackgroundIn continuous renal replacement therapy (CRRT), administration of anticoagulants is necessary for achieving a certain level of filter lifetime. Generally, anticoagulant doses are controlled to keep activated partial thromboplastin time and other indicators within a certain target range, regardless of the membrane materials used for the filter. However, in actual clinical practice, the filter lifetime varies significantly depending on the membrane material used. The objective of this study was to demonstrate that the minimum anticoagulant dose necessary for prolonging the filter lifetime while reducing the risk of hemorrhagic complications varies depending on the type of membrane.MethodsIn three beagles, hemodiafiltration was performed with hemofilters using polysulfone (PS), polymethylmethacrylate (PMMA), and AN69ST membranes separately. The minimum dose of nafamostat mesylate (NM) that would allow for 6 h of hemodiafiltration (required dose) was investigated for each membrane material.ResultsThe NM doses required for 6 h of hemodiafiltration were 2 mg/kg/h for the PS membrane, 6 mg/kg/h for the PMMA membrane, and 6 mg/kg/h for the AN69ST membrane.ConclusionFor hemodiafiltration performed in beagles, the required NM dose varied for each filter membrane material. Using the optimal anticoagulant dose for each membrane material would allow for safer CRRT performance.

Quantitative filter forensics: Size distribution and particulate matter concentrations in residential buildings.

We applied filter forensics, the analysis of dust from the heating, ventilation, and air-conditioning (HVAC) filters, to measure particle size distribution in 21 residences in Toronto, Canada over a year. Four filters with different nominal efficiencies (Minimum Efficiency Reporting Value (MERV) 8-14 from ASHRAE Standard 52.2) were deployed in each residence each for three months, while the effective filtration volumes (the product of flow rate, runtime, and in-situ filter efficiency) were characterized over each filter lifetime. Using extraction and laser diffraction, we found that approximately 90% of the volumetric distributions were >10µm and the volume median diameter (VMD) ranged from 23.4 to 75.1µm. Using quantitative filter forensics (QFF), total suspended particle (TSP) concentrations ranged from 2.9 to 823.7µg/m3 (median=89.8µg/m3 ) with a moderate correlation with the content of TSP on the filters (in terms of g) and with the TSP effective filtration volume (m3 ) indicating the importance of both filter forensics and HVAC metadata parameters to QFF concentration estimates. There was no strong correlation between PM10 or PM2.5 concentrations and hourly airborne particle number concentrations measured by low-cost sensors suggesting an evaluation of QFF is warranted, particularly for the exploration of smaller particles.