Filter Penetration Research Articles

Protective Efficiency of Filtering Respirators

In the article the dependence of protective efficiency of the respiratory protective devices on the filter penetration coefficient and leakage of the polluted air through sealing band was established. The leakage was determined by the ratio of the filter resistance and the sealing band. The relationship between increasing the filter resistance and worsening the protective effectiveness of respiratory protective device was established. Factors that worsen the respirator quality were determined: the gaps between the face and half-mask, weak tension of the head harness. Filter parameters that will ensure high efficiency for respirators of the second protection class were established.

Encountered a Black Swan During ERCP: A Rare Case of IVC Filter Migration to Ampulla

Inferior Vena Cava (IVC) filter penetration of the vessel wall into surrounding gastrointestinal (GI) structures is a possible but rare complication. Few cases of IVC filter migration into the duodenum have been reported. We present a case of Greenfield IVC filter penetrating in the ampulla, visualized only during ERCP. To the best of our knowledge, IVC filter migration to ampulla has not been reported in the literature. An 87-year-old female presented to the hospital with melena, and abdominal pain. Her past medical history was significant for Atrial Fibrillation and recurrent DVTs for which she takes coumadin. The patient had a Greenfield IVC filter placed around 20 years ago for her recurrent DVTs as she had contraindication to anticoagulation at that time. She did not follow-up and the filter was not removed. On examination upper abdomen was tender. Lab studies revealed anemia (Hemoglobin 7.5 mg/dl), supratherapeutic INR and abnormal liver function test suggestive of cholestasis. MRCP showed dilated bile ducts and choledocholithiasis. Upper GI endoscopy was performed but did not reveal any source of bleeding. GI bleeding resolved spontaneously with reversal of anticoagulation and supportive care. ERCP was then performed for management of choledocholithiasis which incidentally revealed a protruding piece of hardware which was consistent with Greenfield filter prawn (Image 1). The protruding prawn was grasped with the biopsy forceps and fluoroscopic images were taken (Image 2). Images confirmed it to be a part of IVC filter while the rest of body was extraluminal, likely in the IVC. It was left undisturbed while choledocholithiasis was treated with sphincterotomy. Patient's abdominal pain resolved.Considering patient's age, comorbidities and her being asymptomatic, it was decided to manage the perforating filter conservatively. Long standing IVC filter can perforate the duodenal wall and can result in obscure GI bleeding. Generally, filters migrating to the duodenal wall can be seen on endoscopy with forward view scopes. We believe the migrated IVC filter caused GI bleeding in our patient which was missed on EGD. IVC filter strut at the ampulla was visualized only during an ERCP. One of the implications of this rare finding is that if there is high suspicion for IVC filter perforation, then inspection of the ampulla with a duodenoscope should be considered as well. Our case also highlights the importance of timely removal of IVC filters.Figure: Leg of IVC filter seen perforating at Ampulla during ERCP.Figure: Fluoroscopic image showing IVC filter.

Asymptomatic Duodenal Penetration by Inferior Vena Cava Filter: 3-Year Follow-up

INTRODUCTION: Inferior vena cava (IVC) filters are used to reduce the risk of thromboembolic events in subjects who are either not a candidate for anticoagulant therapy (ACT) or have failed ACT. Complications of IVC filters could be either early (bleeding, infection, acute venous thrombosis, hematoma and arteriovenous fistula formation) or late (filter migration and chronic thrombosis/recurrent thromboembolism). IVC filter penetration of the surrounding structures including bowel (duodenum), is a known although rare complication which can manifest as abdominal pain, gastrointestinal bleeding, cava-duodenal fistula, or small bowel obstruction. We present a rare case of asymptomatic duodenal penetration by IVC filter which was managed conservatively. CASE REPORT A 64-year-old male with history of multiple, recurrent DVTs and pulmonary embolism secondary to heterozygous MTHFR gene mutation presented to our facility 3 years ago for progressively worsening dysphagia. He had Greenfield IVC filter placed a few years back and was on long term ACT. Esophagogastroduodenoscopy(EGD) incidentally revealed a piece of metal protruding from the second portion of the duodenal wall, as shown in figure 1.CT scan of the abdomen and pelvis showed multiple IVC filter struts extending beyond the IVC wall with one of the struts extending anteriorly to penetrate the duodenal wall, as in figure 2. IVC venography confirmed CT scan findings, showing four struts of a patent IVC filter extending beyond the IVC wall. Vascular surgery (VS) and interventional radiology (IR) recommended conservative management in the absence of any symptoms. He remained asymptomatic for the next three years. Repeat EGD performed 3 years later revealed unchanged IVC filter strut in the duodenum, as shown in figure 3.Figure: EGD performed in 2013 showing IVC filter strut in duodenum.Figure: CT scan of the abdomen and pelvis showing multiple IVC filter struts extending beyond the IVC wall, with one of the struts penetrating duodenal wall.Figure: EGD performed in 2016 showing IVC filter strut at the same location in duodenum.DISCUSSION IVC filter migration into the GI tract is extremely rare and patients are usually symptomatic. Duodenum is the most common extra-caval involved organ. Current literature directs surgical treatment of patients with symptomatic duodenal perforation, however, there are no consensus guidelines for management of asymptomatic IVC filter penetrations in GI tract. Such cases should be managed by a multidisciplinary team of IR, VS and gastroenterologist. CONCLUSION Our patient was managed successfully with a non-surgical approach and remained asymptomatic during next 3 years.

Development of a HPLC method for determination of four UV filters in sunscreen and its application to skin penetration studies.

This study describes the development, validation and application of a high-performance liquid chromatography (HPLC) method for the simultaneous determination of the in vitro skin penetration profile of four UV filters on porcine skin. Experiments were carried out on a gel-cream formulation containing the following UV filters: diethylamino hydroxybenzoyl hexyl benzoate (DHHB), bis-ethylhexyloxyphenol methoxyphenyl triazine (BEMT), methylene bis-benzotriazolyl tetramethylbutylphenol (MBBT) and ethylhexyl triazone (EHT). The HPLC method demonstrated suitable selectivity, linearity (10.0-50.0 μg/mL), precision, accuracy and recovery from porcine skin and sunscreen formulation. The in vitro skin penetration profile was evaluated using Franz vertical diffusion cells for 24 h after application on porcine ear skin. None of the UV filters penetrated the porcine skin. Most of them stayed on the skin surface (>90%) and only BEMT, EHT and DHHB reached the dermis plus epidermis layer. These results are in agreement with previous results in the literature. Therefore, the analytical method was useful to evaluate the in vitro skin penetration of the UV filters and may help the development of safer and effective sunscreen products.

Knowledge Spillovers and Absorptive Capacity Institutional Evidence from the German Mittelstandd

Recent extensions to the knowledge spillover theory of entrepreneurship (KSTE) show that the successful commercialization of new knowledge by incumbents depends on their absorptive capacities. For policy-makers focusing on increasing incumbents’ innovative performance, the systematic reduction of knowledge filter through improved absorptive capacities thus becomes a crucial goal. While the general working mechanisms of knowledge filter have been analyzed within the KSTE framework, few institutional solutions to increase absorptive capacities have been put forth. This study provides an initial case study explaining a specific institutional framework fostering the systematic penetration of knowledge filters by incumbent firms in the case of German SMEs. Using a set of 177 in-depth interviews with firm representatives, the system of interrelated organizations, institutional arrangements, shared values and economic incentives associated with the institutional structures for knowledge spillovers for German SMEs are described. I identify institutional characteristics connected to the dual system of vocational training, regulatory measures and economic incentives mutually enforcing and fostering broad knowledge spillovers. This exploratory approach enables deriving hypotheses for the further study of knowledge filters as well as policy implications for the design of institutions increasing incumbents’ absorptive capacities.

Filter penetration and breathing resistance evaluation of respirators and dust masks

ABSTRACTThe primary objective of this study was to compare the filter performance of a representative selection of uncertified dust masks relative to the filter performance of a set of NIOSH-approved N95 filtering face-piece respirators (FFRs). Five different models of commercially available dust masks were selected for this study. Filter penetration of new dust masks was evaluated against a sodium chloride aerosol. Breathing resistance (BR) of new dust masks and FFRs was then measured for 120 min while challenging the dust masks and FFRs with Arizona road dust (ARD) at 25°C and 30% relative humidity. Results demonstrated that a wide range of maximum filter penetration was observed among the dust masks tested in this study (3–75% at the most penetrating particle size (p < 0.001). The breathing resistances of the unused FFRs and dust masks did not vary greatly (8–13 mm H2O) but were significantly different (p < 0.001). After dust loading there was a significant difference between the BR caused by the ARD dust layer on each FFR and dust mask. Microscopic analysis of the external layer of each dust mask and FFR suggests that different collection media in the external layer influences the development of the dust layer and therefore affects the increase in BR differently between the tested models. Two of the dust masks had penetration values < 5% and quality factors (0.26 and 0.33) comparable to those obtained for the two FFRs (0.23 and 0.31). However, the remaining three dust masks, those with penetration > 15%, had quality factors ranging between 0.04–0.15 primarily because their initial BR remained relatively high. These results indicate that some dust masks analysed during this research did not have an expected very low BR to compensate for their high penetration.

Laser-Assisted Removal of Embedded Vena Cava Filters: A 5-Year First-in-Human Study

Many patients are subjected to the potential risks and morbidity associated with an indwelling inferior vena cava (IVC) filter when standard methods fail to remove the filter. We evaluated the safety and effectiveness of the excimer laser sheath technique for removing embedded IVC filters. Over a 5-year period, 251 consecutive patients undergoing laser-assisted filter retrieval were prospectively enrolled. There were 103 men and 148 women (mean, 46 years; range, 15-82 years). Indications for retrieval included symptomatic acute IVC thrombosis, chronic IVC occlusion, and/or pain from filter penetration. Retrieval was also performed to prevent risks from prolonged implantation and potentially to eliminate the need for lifelong anticoagulation. After retrieval failed using three times the standard retrieval force (digitally measured), treatment escalation was attempted using a laser sheath powered by a 308-nm XeCl laser. Success was defined as complete filter detachment and removal from the body. Primary safety outcomes were major procedure-related complications. Laser-assisted retrieval was successful in 249 of 251 patients (99.2%) (95%CI, 97.2%-99.9%), with a mean implantation of 979days, range: 37-7,098days (> 19 years), among retrievable-type filters (n= 211) and permanent-type filters (n= 40). Average force during failed attempts without laser was 6.7 vs3.8 lbs during laser-assisted retrievals (P< .0001). The major complication rate was 1.6%(95%CI, 0.4%-4.0%), and all were successfully treated. Successful retrieval allowed cessation of anticoagulation in 45 of 46 patients (98%) (95%CI, 88%-99%) and alleviated filter-related morbidity in 55 of 57 patients (96%) (95%CI, 88%-99%). The excimer laser sheath technique is safe and effective for removing embedded IVC filters refractory to standard retrieval and high force. This technique can be used to alleviate or prevent filter-related morbidity and may allow cessation of filter-related anticoagulation. ClinicalTrials.gov; No.: NCT01158482; URL: www.clinicaltrials.gov.

Totally analytical closure of space filtered Navier–Stokes for arbitrary Reynolds number: Part II. Resolution algorithms, validations

ABSTRACTFor uniform measure δ Gaussian filter, Part I derives the totally analytical aFNS theory closing rigorously space filtered Navier–Stokes (NS) partial differential equation (PDE) system absent a Reynolds number (Re) assumption. aFNS theory state variable is scaled O(1; δ2; δ3) via classic fluid mechanics perturbation theory which also identifies the O(δ2) elliptic PDE system. Filter penetration of domain bounding surfaces requires O(1) PDE system inclusion of boundary commutation error (BCE) integrals. For the O(1; δ2), PDE system to be bounded domain well-posed requires derivation of domain encompassing nonhomogeneous Dirichlet boundary conditions (DBC). Resolution of BCE and DBC requirements is theorized via O(δ4) approximate deconvolution (AD) Galerkin differential definition weak form algorithms. Amenable to any space-time discretization, detailed is aFNS theory insertion in the optimal Galerkin weak form CFD algorithm, finite element linear tensor product basis implemented. Coupled Galerkin CFD/BCE/DBC code a posteriori data reported herein validate theory resolution algorithms including accuracy/convergence assessments.

Cellulose acetate nanofiber electrospun on nylon substrate as novel composite matrix for efficient, heat-resistant, air filters

Cellulose acetate (CA) nanofibers were prepared via electrospinning to obtain a high quality factor (QF) fibrous mat for aerosol particle filtration. To this purpose, special attention was paid to the substrate material used to collect the nanofibers. Different materials (glassine paper, Lyocell, nylon grids) were investigated for use as substrates in the membrane spinning process. Membrane and membrane fiber morphologies were characterized by optical microscope and scanning electron microscope (SEM) analyses. Results show that the arrangement of the membrane fibers is directly correlated to the morphology of the collecting substrate material. Experiments shows that the electrospun nanofiber web tends to recreate the specific character of the supporting textile texture. A support with a pronounced bi-dimensional structure should be preferred. A regular grid, made of nylon, is selected for the composition with CA nanofibres.By maintaining the same support, various electrospinning parameters such as the spinning solution CA concentration (14wt%, 18wt%) and spinning volume (15–120μL) of the membranes are tested in terms of air filtration performance. Filtration tests are performed by measuring the filter penetration against neutralized aerosol particles. Basis weight, solid volume fraction and thickness parameter were investigated to find the best arrangement.The filtration efficiency of stacked layers is analyzed at variable thickness of the building block element. An electrospun membrane of above 60μm thickness, combined with the selected substrate, increases the QF and improve its reproducibility. The QF can be further increased with an optimized porosity of the nylon substrate. The best QF of 0.080±0.050Pa−1 at 300nm was obtained by spinning a 14wt% CA solution in an acetone- DMSO-acetic acid solvent mixture on a nylon grid with 100μm mesh size producing fleeces with a very low pressure drop (7Pa). Thermogravimetric analyses (TGA) and SEM imaging demonstrated the stability of the composite filter morphology up to 200°C.

Solving the knowledge filter puzzle: absorptive capacity, entrepreneurship and regional development

New growth theory addresses the important role of knowledge in regional economic growth. However, knowledge is not always commercially exploited. The obstacles preventing knowledge commercialization are known as the knowledge filter. The literature has identified entrepreneurship as a mechanism of overcoming the knowledge filter. This article further argues that absorptive capacity is another effective factor that can solve the knowledge filter puzzle. To test this hypothesis, we introduce a new approach to measuring regional absorptive capacity and, via exploratory factor analysis, identifies two types of absorptive capacity: cognitive capacity and technical capacity. Multivariate analysis finds a significant moderating role of cognitive capacity (and to a lesser extent technical capacity) in the impact of knowledge on regional economic performance and therefore supports absorptive capacity as an effective mechanism for the penetration of the knowledge filter. The empirical results also provide additional evidence on the role of entrepreneurship in commercializing new knowledge and penetrating the knowledge filter.

THE CAVAL PENETRATION BY PERMANENT IMPLANTATION OF THE TEMPORARY INFERIOR VENA CAVA FILTERS AND LONG-TERM CLINICAL OUTCOMES: A SINGLE CENTER EXPERIENCE

The high incidence of caval penetration after inferior vena cava (IVC) filter implantation has been reported. However little is known regarding clinical outcomes related to caval penetration of IVC filters. We evaluated a total of 87 IVC filters that implanted between July 2008 and June 2014 in

Effectiveness of N95 respirators versus surgical masks in protecting health care workers from acute respiratory infection: a systematic review and meta-analysis.

Conflicting recommendations exist related to which facial protection should be used by health care workers to prevent transmission of acute respiratory infections, including pandemic influenza. We performed a systematic review of both clinical and surrogate exposure data comparing N95 respirators and surgical masks for the prevention of transmissible acute respiratory infections. We searched various electronic databases and the grey literature for relevant studies published from January 1990 to December 2014. Randomized controlled trials (RCTs), cohort studies and case-control studies that included data on health care workers wearing N95 respirators and surgical masks to prevent acute respiratory infections were included in the meta-analysis. Surrogate exposure studies comparing N95 respirators and surgical masks using manikins or adult volunteers under simulated conditions were summarized separately. Outcomes from clinical studies were laboratory-confirmed respiratory infection, influenza-like illness and workplace absenteeism. Outcomes from surrogate exposure studies were filter penetration, face-seal leakage and total inward leakage. We identified 6 clinical studies (3 RCTs, 1 cohort study and 2 case-control studies) and 23 surrogate exposure studies. In the meta-analysis of the clinical studies, we found no significant difference between N95 respirators and surgical masks in associated risk of (a) laboratory-confirmed respiratory infection (RCTs: odds ratio [OR] 0.89, 95% confidence interval [CI] 0.64-1.24; cohort study: OR 0.43, 95% CI 0.03-6.41; case-control studies: OR 0.91, 95% CI 0.25-3.36); (b) influenza-like illness (RCTs: OR 0.51, 95% CI 0.19-1.41); or (c) reported workplace absenteeism (RCT: OR 0.92, 95% CI 0.57-1.50). In the surrogate exposure studies, N95 respirators were associated with less filter penetration, less face-seal leakage and less total inward leakage under laboratory experimental conditions, compared with surgical masks. Although N95 respirators appeared to have a protective advantage over surgical masks in laboratory settings, our meta-analysis showed that there were insufficient data to determine definitively whether N95 respirators are superior to surgical masks in protecting health care workers against transmissible acute respiratory infections in clinical settings.

Temporal changes in filtering-facepiece respirator fit

ABSTRACTA three-year study examined changes in N95 filtering-facepiece respirator (FFR) fit at six-month intervals and the relationship between fit and changes in weight for 229 subjects. During each visit, subjects performed a total of nine fit tests using three samples of the same FFR model. Inward leakage and filter penetration were measured for each donned respirator to determine face seal leakage (FSL). A total of 195 subjects completed the second visit and 134 subjects completed all seven visits. Acceptable fit was defined as 90th percentile FSL ≤ 5% and at least one fit factor ≥ 100. An unacceptable fit was observed for 14, 10, 7, 12, 15, and 16% of subjects on Visits 2–7, respectively. The predicted risk of an unacceptable fit increased with increasing length of time between fit tests, from 10% at Year 1 to 20% at Year 2 and to 25% at Year 3. Twenty-four percent of subjects who lost ≥ 20 lb had an unacceptable fit; these percentages ranged from 7–17% for subjects with lower weight losses or any degree of weight gain. Results support the current OSHA requirement for annual fit testing and suggest that respirator users who lose more than 20 lb should be re-tested for respirator fit.

Air filtration and antimicrobial capabilities of electrospun PLA/PHB containing ionic liquid

Abstract Polylactide/polyhydroxybutyrate ( PLA / PHB ) nanofibers were prepared by electrospinning and functionalized with different amounts of ammonium-based ionic liquid ( IL ) belonging to quaternary ammonium compounds ( QACs ) to obtain a fibrous mat with antimicrobial properties for aerosol particle filtration. The filtration performance of these biopolymer nanofiber mats was evaluated by measuring the filter penetration of sodium chloride (NaCl) aerosol particles ranging from 20 to 600 nm. These filtration test results showed that the quality factors remain unvaried with the addition of IL and depend mostly on the electrospinning time. The “multi-layering” method was adopted to fabricate highly efficient nanofiber filters with a greatly reduced pressure drop. A quantitative analysis of the antimicrobial activity is also presented. The results show that renewable materials, such as PLA blended with PHB , can be considered for biodegradable filters, in line with the future trend to develop eco-sustainable products. Adding QAC salt to the biopolymer blend combines these qualities with an innovative bactericidal nanomaterial.

Aerosol Filtration with Mobility-Classified Particles: Role of Multiply Charged Particles in Skewing Penetration Measurements

Filter media exhibit strong particle-size dependent capture characteristics that have a complicated dependence to filter properties and operating conditions. As simulation-based determination of the filtration characteristics of real media is very challenging, accurate experimental approaches are critically necessary. Conventionally, filter penetration measurements were made using test particles extracted from a differential mobility analyzer (DMA) and measuring the ratio of particle counts downstream of the filter to that upstream. Size-dependent filter penetration can be directly determined from these measurements if the DMA was operated at high resolution and the contribution of multiply charged particles was negligible. The accuracy of this well-established approach has, however, never been fully assessed. In this study, the influence of multiply charged particles to the filter efficiency measurements is determined using a system-modeling approach. The model results suggest that the contribution of mu...

Respiratory-Induced Haemodynamic Changes: A Contributing Factor to IVC Filter Penetration.

The purpose of the study is to evaluate the influence of respiratory-induced vena caval hemodynamic changes on filter migration/penetration. After placement of either a Gunther Tulip or Celect IVC filter, 101 consecutive patients scheduled for filter retrieval were prospectively enrolled in this study. Pre-retrieval CT scans were used to assess filter complications and to calculate cross-sectional area in three locations: at level of filter strut fixation, 3 cm above and 3 cm below. A 3D finite element simulation was constructed on these data and direct IVC pressure was recorded during filter retrieval. Cross-sectional areas and pressures of the vena cava were measured during neutral breathing and in Valsalva maneuver and identified filter complications were recorded. A statistical analysis of these variables was then performed. During Valsalva maneuvers, a 60 % decrease of the IVC cross-sectional area and a fivefold increase in the IVC pressure were identified (p < 0.001). There was a statistically significant difference in the reduction of the cross-sectional area at the filter strut level (p < 0.001) in patient with filter penetration. Difficulty in filter retrieval was higher in penetrated or tilted filters (p < 0.001; p = 0.005). 3D computational models showed significant IVC deformation around the filter during Valsalva maneuver. Caval morphology and hemodynamics are clearly affected by Valsalva maneuvers. A physiological reduction of IVC cross-sectional area is associated with higher risk of filter penetration, despite short dwell times. Physiologic data should be used to improve future filter designs to remain safely implanted over longer dwell times.

Evaluation of the Effect of the Volume Throughput and Maximum Flux of Low-Surface-Tension Fluids on Bacterial Penetration of 0.2 Micron-Rated Filters during Process-Specific Filter Validation Testing.

Evaluation of the Effect of the Volume Throughput and Maximum Flux of Low-Surface-Tension Fluids on Bacterial Penetration of 0.2 Micron-Rated Filters during Process-Specific Filter Validation Testing.

4-Methylbenzylidene camphor microspheres: reconstituted epidermis (Skinethic®) permeation and distribution.

The UV filter 3(4-methylbenzylidene) camphor (4-MBC) is a common ingredient in sunscreen cosmetic products. However, different 'in vitro' and 'in vivo' studies suggest that 4-MBC can cause endocrine disrupting effects. Therefore, there is a need for new systems able to minimize the skin penetration of this UV filter. The aim of this study was to evaluate cutaneous permeation and distribution, through and into EPISKIN reconstituted epidermis (RE) from an O/W emulsion containing 4-MBC free or encapsulated in polymeric substantive microspheres. Microspheres containing 4-MBC were prepared using the emulsification-solvent evaporation method and characterized for shape and surface morphology and encapsulation efficiency. O/A emulsions containing sunscreen free or encapsulated in microspheres were undergone to permeation tests through RE using vertical diffusion cells. At the end of the in vitro permeation experiments, the skin was subjected to tape stripping procedure to separate stratum corneum from viable epidermis. Each part was properly treated to extract the sunscreen retained and subject to quantitative analysis. The encapsulation of the sunscreen in the microspheres remarkably reduced the permeation of 4-MBC and increased its retention on the skin surface where its action is more desirable. The results of this study confirm the validity of substantive microspheres as an ideal formulation candidate to use in sunscreen preparation as they appear minimizing its systemic uptake and the potential associate toxicological risks. Therefore, more of the active sunscreen remains on the surface of the skin where it is intended to act and a higher activity it will explicate.

Modeling Penetration through Fibrous Filter during Dynamic Filtration

A model to quantitatively describe penetration change during filter clogging through a fiber filter is proposed. This model is developed using two different analytical methods and indicates that filter penetration is a function of the coefficient K and deposited dust mass in the filter. This is verified through a number of laboratory filter experiments. The coefficient K is obtained using regression analysis via the results of the experiments with different dust loading parameters. K is expressed as a function of aerosol particle diameter, efficiency, and filter material. A larger value of K illustrates a higher increasing rate of efficiency during clogging. A larger value of K also correlates with a smaller aerosol particle size and a higher penetration filter.

Delayed Lumbar Artery Laceration and Symptomatic Retroperitoneal Hemorrhage Following IVC Filter Placement

Inferior vena cava filters are placed in selected patients to protect against potentially fatal pulmonary embolism. Generally, filter placement is regarded as a safe procedure although rare complications may arise. Recurrent thromboembolic events are the most common complications assoiated with inferior vena cava filters; however, there are multiple reports of filter fracture, migration, embolization, penetration and perforation. The aim of this report is to illustrate a serious potential complication of inferior vena cava filters. We report a rare case of symptomatic retroperitoneal hemorrhage occurring 3 weeks after filter placement treated successfully with selective arterial embolization of a lumbar artery laceration. This case serves to highlight the importance of retrieving filters when they are no longer beneficial.