Polymethylpentene Research Articles

Accumulation of Multipotent Progenitor Cells on Polymethylpentene Membranes During Extracorporeal Membrane Oxygenation.

Multipotent progenitor cells were mobilized during pediatric extracorporeal membrane oxygenation (ECMO). We hypothesize that these cells also adhered onto polymethylpentene (PMP) fibers within the membrane oxygenator (MO) during adult ECMO support. Mononuclear cells were removed from the surface of explanted PMP-MOs (n = 16). Endothelial-like outgrowth and mesenchymal-like cells were characterized by flow cytometric analysis using different surface markers. Spindle-shaped attaching cells were identified early, but without proliferative activity. After long-term cultivation palisading type or cobblestone-type outgrowth cells with high proliferative activity appeared and were characterized as (i) leukocytoid CD45+/CD31+ (CD133+/VEGFR-II+/CD90+/CD14+/CD146dim/CD105dim); (ii) endothelial-like CD45-/CD31+ (VEGF-RII+/CD146+/CD105+/CD133-/CD14-/CD90-); and (iii) mesenchymal-like cells CD45-/CD31- (CD105+/CD90+/CD133dim/VEGFR-II-/CD146-/CD14-). The distribution of the cell populations depended on the MO and cultivation time. Endothelial-like cells formed capillary-like structures and did uptake Dil-acetylated low-density lipoprotein. Endothelial- and mesenchymal-like cells adhered on the surface of PMP-MOs. Further research is needed to identify the clinical relevance of these cells.

Light weight high temperature polymer film capacitors with dielectric loss lower than polypropylene

The dielectric and high voltage performance of polymethylpentene (PMP) is investigated and compared with biaxially-oriented polypropylene (BOPP) for high power density and high temperature capacitor applications. PMP has a melting temperature that is around 60 °C higher than BOPP, while still maintaining low dielectric loss and high charge–discharge efficiency that are comparable to the latter. Furthermore, PMP is the lightest commercial thermoplastic polymer with density of 0.83 g/cm3, which is 8 % lower than BOPP (0.9 g/cm3). PMP is a promising semicrystalline dielectric material that may replace BOPP for high temperature pulsed power and power conditioning applications.

A paediatric ECMO case of plasma leakage through a polymethylpentene oxygenator

Polymethylpentene (PMP) oxygenators, utilised for ECMO, are commonly believed to be resistant to plasma leakage. Whilst uncommon, plasma leakage has been previously reported with PMP fibres, both in vivo and in vitro. We describe a paediatric ECMO case during which plasma leakage occurred and oxygenator function gradually deteriorated, ultimately necessitating device replacement. To our knowledge, this is the first case of plasma leakage described using a PMP device during paediatric ECMO. Subsequent investigation is described, demonstrating that a protein coating reduces the free passage of solution across the PMP membrane.

Cost-effective usage of membrane oxygenators in extracorporeal membrane oxygenation in infants.

Although the poly-methylpentene (PMP) oxygenators have significant advantages in ECMO implementation, their usage may be limited in some situations, which may be related to economic constraints. In this report, we aimed to emphasize our cost-effective usage of a membrane oxygenator at the ECMO setup. We implemented ECMO with eight Capiox® FX05 or Baby RX05 hollow-fiber membrane oxygenators in five neonatal patients. The average ECMO duration was 121 hours (ranging from 41 to 272 hours). Following the termination of the ECMO, the system was broken down into its components for macroscopic analysis. Neither gross blood clots nor plasma leakage were observed in any of the components. The integration of a centrifugal pump and a separate hollow-fiber oxygenator may provide a cost-effective ECMO implementation setup with no adverse effects which may be an encouraging alternative for the low cost usage of ECMO in neonates.

Evaluation of a polymethylpentene fiber mat formed directly on an anode as a battery separator

Battery separator is a porous membrane that separates the positive and negative electrodes to prevent their electrical shorting, yet enables lithium ion transport through the liquid electrolyte in its pores. In this work, a polymethylpentene (PMP) non-woven separator was formed directly on an anode through the electrospinning process. The PMP separator exhibited a much improved thermal dimensional stability compared to a commercial polyolefin separator. It showed negligible shrinkage in the 150°C oven test, while the shrinkage was close to 55% for a commercial separator in the machine direction. It also enabled good effective ionic conductivity in the range of 1.16–1.44mS/cm when saturated with the liquid electrolyte of 1M LiPF6 in ethylene carbonate/diethyl carbonate (1:2 by volume). The cell performance was tested in coin cells with the LiNi1/3Co1/3Mn1/3O2 cathode and the graphite anode. The cells with the PMP separators displayed stable cycling performance and good rate capabilities. However, the PMP separators showed low tensile strengths and the effect of the low tensile strengths on the performance of large format batteries needs further investigation.

Case Report: Remote monitoring using Spectrum Medical Live Vue allows improved response time and improved quality of care for patients on cardiopulmonary support

Clinician rounding on bedside extracorporeal membrane oxygenation (ECMO) is a common coverage practice at many centers across the USA. Occasionally, clinical issues or concerns may go unnoticed for a considerable period of time during the intervals of clinician rounds. We report a case utilizing the LiveVue (Spectrum Medical, Fort Mill, SC) remote monitoring for care of a patient on ECMO. A patient was placed on veno-arterial (VA) ECMO in our intensive care unit, using a Rotaflow centrifugal pump and a Quadrox D polymethylpentene (PMP) fiber oxygenator (both Maquet, Fairfield, NJ). Following ECMO initiation and stabilization, a two-hour rounding schedule was established for the covering perfusionist. On day two, shortly after the perfusionist had rounded, the ECMO flow began fluctuating between 0.1 and 2.1 L/min. A compliance alert (i.e. red flashing notification) was recognized by the perfusion team on a large screen monitor installed in the perfusion pump room. Immediate response from the perfusion team identified venous inflow obstruction due to cannula malposition. The pump revolutions per minute (rpm) and, thus, the resulting flow were temporarily reduced to prevent vessel intimal damage and the surgical team was summoned to reposition the venous cannula. Later in that ECMO run, a steady rise in pre-oxygenator pressure was noted by the perfusionist. This increasingly concerning event was able to be trended and monitored with the LiveVue from a remote location. After a few hours, a compliance alert was noticed again on the LiveVue screen in the pump room. The pre-oxygenator pressure increased by 150 mmHg and the circuit flow decreased by half. Again, the perfusionist response was immediate and an oxygenator change-out ensued. Once more, a potentially dangerous clinical scenario was avoided with continuous critical parameter remote monitoring using the LiveVue system.

Insensible water loss from the Hilite 2400LT oxygenator: an in vitro study

Neonatal extracorporeal membrane oxygenation (ECMO) patients are particularly vulnerable to the effects of uncompensated insensible water loss resulting in hypernatraemia. There exists a long-standing relationship between hypernatraemia and varying degrees of cerebral dysfunction. The aim of this study is to explore the degree to which free water loss occurs across a commonly used ECMO oxygenator, the polymethylpentene (PMP) membrane Hilite 2400LT (Medos, Medizintechnik AG, Stolberg, Germany). The secondary aim is to assess to what extent the addition of heat and/or humidity ameliorates this water loss. An ECMO circuit consisting of a centrifugal pump and a Hilite 2400LT oxygenator was primed with crystalloid and albumin. Each experimental trial was carried out in triplicate, with gas flow rates of 1, 3 and 4.8 L/min being investigated. Fluid loss was assessed at six time points over a 24-hour period. Water loss increased significantly from 1 to 3 L/min gas flow (p=0.05) and from 3 to 4.8 L/min gas flow (p=0.025). The mean water loss differences between the differing gas flow trials per L/min gas flow were non-significant (72.4 ±3.9 ml/24 hrs). The effect of heating the gas to 37 °C did not significantly alter water loss, whereas heat and humidity reduced water loss significantly (p=0.009). Insensible water loss from a Hilite 2400LT oxygenator is approximately 72 ml/day per L/min gas flow over 24 hrs. Heating and humidifying the gas reduces the fluid loss significantly to approximately 8 ml/L/min gas flow over 24 hrs (p=0.009).

Neonatal Extracorporeal Membrane Oxygenation Devices, Techniques and Team Roles: 2011 Survey Results of the United States’ Extracorporeal Life Support Organization Centers

In early 2011, surveys of active Extracorporeal Life Support Organization (ELSO) centers within the United States were conducted by electronic mail regarding neonatal Extracorporeal Membrane Oxygenation (ECMO) equipment and professional staff. Seventy-four of 111 (67%) U.S. centers listed in the ELSO directory as neonatal centers responded to the survey. Of the responding centers, 53% routinely used roller pumps for neonatal ECMO, 15% reported using centrifugal pumps and 32% reported using a combination of both. Of the centers using centrifugal pumps, 51% reported that they do not use a compliance bladder in the circuit. The majority (95%) of roller pump users reported using a compliance bladder and 97% reported using Tygon® S-97-E tubing in the raceway of their ECMO circuits. Silicone membrane oxygenators were reportedly used by 25% of the respondents, 5% reported using micro-porous hollow fiber oxygenators (MPHF), 70%reported using polymethylpentene (PMP) hollow fiber oxygenators and 5% reported using a combination of the different types. Some form of in-line blood monitoring was used by 88% of the responding centers and 63% of responding centers reported using a circuit surface coating. Anticoagulation monitoring via the activated clotting time (ACT) was reported by 100% of the reporting centers. The use of extracorporeal cardiopulmonary resuscitation (ECPR) was reported by 53% of the responding centers with 82% of those centers using a crystalloid primed circuit to initiate ECPR. A cooling protocol was used by 77% of the centers which have an ECPR program. When these data are compared with surveys from 2002 and 2008 it shows that the use of silicone membrane oxygenators continues to decline, the use of centrifugal pumps continues to increase and ECMO personnel continues to be comprised of multidisciplinary groups of dedicated allied health care professionals.

Evaluation of two pediatric polymethyl pentene membrane oxygenators with pulsatile and non-pulsatile perfusion

This experiment sought to compare two polymethyl pentene (PMP) hollow-fiber membrane oxygenators: the Medos HILITE 2400 LT and the Maquet Quadrox-iD Pediatric in terms of transmembrane pressure gradients and hemodynamic energy preservation under both pulsatile and non-pulsatile conditions. A simulated pediatric extracorporeal life support (ECLS) circuit was used to test these two oxygenators. The circuit consisted of a roller pump, ¼ inch tubing for both arterial and venous lines, an oxygenator, and a venous reservoir served as a pseudo-patient. Three pressure transducers were placed upstream and downstream of the oxygenator and the distal arterial line. The experimental system was primed with lactated Ringer's solution and packed human red blood cells to maintain a hematocrit of 40%.The total volume was 600 ml, including the 350 ml volume of the pseudo-patient.The tests were performed at six flow rates (250, 500, 750, 1000, 1250, 1500 ml/min) and three distal arterial line pressures (MAP) (60, 80, 100 mmHg), under both pulsatile and non-pulsatile perfusion modes.The temperature was kept constant at 37°C for all tests. Both oxygenators had adequate performances in pressure drop and hemodynamic energy preservation. There were no significant differences between pre- and post-oxygenators for mean pressure (MP), energy equivalent pressure (EEP) and total hemodynamic energy (THE). During the pulsatile perfusion mode, the HILITE 2400 LT retained a greater percentage of surplus hemodynamic energy (SHE) across the oxygenator. Both the Quadrox-iD Pediatric and HILITE 2400LT PMP membrane oxygenators are suitable for pediatric ECLS therapy under both non-pulsatile and pulsatile perfusion. An optimized combination of flow rate and MAP should be achieved in order to deliver the maximal pulsatile energy in the extracorporeal circuit.

Diffusion-controlled reference material for VOC emissions testing: proof of concept

Because of concerns about indoor air quality, there is growing awareness of the need to reduce the rate at which indoor materials and products emit volatile organic compounds (VOCs). To meet consumer demand for low emitting products, manufacturers are increasingly submitting materials to independent laboratories for emissions testing. However, the same product tested by different laboratories can result in very different emissions profiles because of a general lack of test validation procedures. There is a need for a reference material that can be used as a known emissions source and that will have the same emission rate when tested by different laboratories under the same conditions. A reference material was created by loading toluene into a polymethyl pentene film. A fundamental emissions model was used to predict the toluene emissions profile. Measured VOC emissions profiles using small-chamber emissions tests compared reasonably well to the emissions profile predicted using the emissions model, demonstrating the feasibility of the proposed approach to create a diffusion-controlled reference material. To calibrate emissions test chambers and improve the reproducibility of VOC emission measurements among different laboratories, a reference material has been created using a polymer film loaded with a representative VOC. Initial results show that the film's VOC emission profile measured in a conventional test chamber compares well to predictions based on independently determined material/chemical properties and a fundamental emissions model. The use of such reference materials has the potential to build consensus and confidence in emissions testing as well as 'level the playing field' for product testing laboratories and manufacturers.

Adhesion Loss of Syrups in a Metering Glass Which Consists of a Low Surface Free Energy Material

We previously reported a strong positive correlation between syrup viscosity and the rate of syrup loss due to adhesion to a glass metering device. In this study, we examined differences in the surface free energies of metering devices made of different polymeric materials, since reducing adhesion loss to metering devices could improve the efficiency of drug preparation involving highly viscous syrups. Among metering devices made of glass only, glass with a silicone coating (SLC), polypropylene (PP), and polymethylpentene (PMP) the surface free energy of the glass-only metering device was the highest (49.2 mN/m). The adhesion loss obtained for highly viscous syrups in the PP and PMP metering devices was significantly lower than that of the glass metering device. Measurements of syrup contact angles suggested that in metering devices made of PP and PMP, which have low surface free energies, a decrease in the spreading wetting of syrups was a factor in reducing the rate of adhesion loss. Thus irrespective of the syrup viscosity being measured, metering devices produced from materials with low surface free energies can reduce the time required to prepare prescriptions without compromising the accuracy of drug preparation.

Assessment of risk of circuit infection in patients with severe acute respiratory distress syndrome on extracorporeal life support

Background: Bioline-coated poly-methylpentene (PMP) membrane oxygenators (MO) are used for extracorporeal membrane oxygenation (ECMO) to improve gas exchange in patients with severe acute respiratory distress syndrome (ARDS). The aim of the present study was to assess the risk of circuit infection after long-term treatment of PMP-MO.

Nanopatterned polymethylpentene substrates fabricated by injection molding for biophotonic applications

This paper reports the well-controlled replication of nanostructures with features sizes as small as 50 nm on the surface of polymethylpentene (PMP) substrates by injection molding. A 2″ silicon wafer carrying the nanostructures served as exchangeable mold insert. This PMP injection molding process is aimed at developing a planar optical polymer waveguide platform for evanescent wave sensing. In particular we focus on disposable polymer optical biochips for the label-free detection of bio-molecules.

Fabrication of diffractive optical elements inside polymers by femtosecond laser irradiation

Bragg-type gratings were prepared by irradiation inside a series of optical polymers with femtosecond laser pulses and the preparation conditions of the grating were examined. Repeated scanning irradiation with femtosecond laser pulses formed gratings due to refractive index changes inside polymers. Among the polymers examined in the present study, polymethylpentene (PMP) showed the highest diffraction efficiency, which was an order of magnitude higher than those of other optical polymers. The density of PMP was the lowest among the polymers evaluated in the present study, and the large volume contraction based on its low density was responsible for the larger refractive index change of PMP. Furthermore, we fabricated large-area diffractive optical elements (DOEs) in PMP measuring 15 × 25 mm 2 by widening the scanning area.

Efficiency in Extracorporeal Membrane Oxygenation—Cellular Deposits on Polymethypentene Membranes Increase Resistance to Blood Flow and Reduce Gas Exchange Capacity

Bioline-coated polymethylpentene (PMP) membrane oxygenators (MO) are used for extracorporeal membrane oxygenation (ECMO) to improve gas exchange in patients with severe acute respiratory distress syndrome (ARDS). However, in some patients, long-term durability is limited due to fibrous and cellular accumulations on the gas exchange surface which can increase resistance to blood flow and diffusion path. These surface deposits of PMP MO after removal were studied with scanning electron and fluorescence microscopy techniques. Three of 31 patients supported by a PMP MO in an ECMO setting required a replacement of the oxygenator after a mean support interval of 11 +/- 7 days due to an increase in flow resistance and an impairment of the gas exchange capacity. The membrane surface of the MO was covered with a fibrous network with imbedded platelets and red blood cells. A membranous structure composed of single cells and clusters of cells covered large areas of the PMP fibers. We assume that these cellular deposits lower the efficacy of ECMO. The identification of these cells could be a key for future therapeutic interventions and improvements in the development of MO.

Design of Conservative Simulated Particles for Validation of a Multiphase Aseptic Process

Simulated food particles with conservative (fast moving and slow heating) properties are required for validation of multiphase aseptic processing for production of shelf-stable low-acid foods. The validation process requires simulated particles to contain residence time tags, thermosensitive implants, and/or bioloads for temperature detection, time-temperature integration, and bactericidal efficacy confirmation. Conservative particle design (CPD) software was used to determine the wall thickness required for conservative behavior of such particles made with polypropylene (PP) and polymethylpentene (PMP) of wall thickness 1 mm (0.0393 inches) and 2 mm (0.0787 inches) containing tube inserts. Thermocouples were inserted in the simulated and real food particles and the particles were heated up to 127 degrees C under pressurized (24 psi) conditions. Based on the heating rates of the real and simulated particles, an appropriate simulated particle was identified for each type of real food particle. This would allow a food processor to use these designed particles with an appropriate tube insert (diameter) to validate an aseptic process for a multiphase food containing any or all the above tested food materials.

Density characterization of femtosecond laser modification in polymers

Bragg-type gratings were prepared by femtosecond laser irradiation in a series of optical polymers. The diffraction efficiency of polymethylpentene (PMP) was an order of magnitude higher than those of other polymers. Repeated scanning irradiation with femtosecond laser light formed gratings by refractive index changes inside the polymers. In PMP, whose density was the lowest among the polymers examined, large volume contraction by femtosecond laser irradiation was observed by transmission electron microscopy. The larger refractive index change of PMP was attributed to its large volume contraction based on its low density.

Extracorporeal Membrane Oxygenation With a Poly-Methylpentene Oxygenator (Quadrox D). The Experience of a Single Italian Centre in Adult Patients With Refractory Cardiogenic Shock

Although microporous polypropylene hollow fiber oxygenators are standard devices used for extracorporeal membrane oxygenation (ECMO), they have limitations such as development of plasma leakage. Poly-methylpentene (PMP) is a new material used for the last generation of oxygenators. We reviewed our experience with a new PMP oxygenator (Quadrox D) and a centrifugal pump (RotaFlow) used to support adult patients with refractory cardiogenic shock. Between January 2000 and April 2007, 25 patients required ECMO for primary or postcardiotomy cardiogenic shock. Eighteen patients were analyzed [mean age 60.2 years; 11 (61%) men; 7 (39%) women]. Nine patients (50%) suffered primary cardiogenic shock. Cardiopulmonary resuscitation was applied in 11 patients (61%) with a mean duration time of 31.5 minutes. Mean ECMO duration time was 7.1 +/- 6.3 days (range, 1-27 days). Intra-aortic balloon pump was used in 13 patients (72.2%) with a mean duration time of 7.7 +/- 5 (range, 2-17 days). Twelve patients (66.7%) survived on ECMO and five patients (27.8%) were discharged. Our results indicate the PMP oxygenator and the centrifugal pump provided acceptable results in terms of surviving on ECMO and discharge. Patients with an initial catastrophic hemodynamic status could benefit by means of a rapid institution of ECMO with PMP oxygenators.

Characterization of Cysts Using Differential Correlation Coefficient Values from Two Dimensional Breast Elastography: Preliminary Study

Although simple cysts are easily identified using sonography, description and management of nonsimple cysts remains uncertain. This study evaluated whether the correlation coefficient differences between breast tissue and lesions, obtained from 2D breast elastography, could potentially distinguish nonsimple cysts from cancers and fibroadenomas. We hypothesized that correlation coefficients in cysts would be dramatically lower than surrounding tissue because noise, imaging artifacts, and particulate matter move randomly and decorrelate quickly under compression, compared with solid tissue. For this preliminary study, 18 breast lesions (7 nonsimple cysts, 4 cancers, and 7 fibroadenomas) underwent imaging with 2D elastography at 7.5 MHz through a TPX (a polymethyl pentene copolymer) 2.5 mm mammographic paddle. Breasts were compressed similar to mammographic positioning and then further compressed for elastography by 1 to 7%. Images were correlated using 2D phase-sensitive speckle tracking algorithms and displacement estimates were accumulated. Correlation coefficient means and standard deviations were measured in the lesion and adjacent tissue, and the differential correlation coefficient (DCC) was introduced as the difference between these values normalized to the correlation coefficient of adjacent tissue. Mean DCC values in nonsimple cysts were 24.2 ± 11.6%, 5.7 ± 6.3% for fibroadenomas, and 3.8 ± 2.9 % for cancers ( p < 0.05). Some of the cysts appeared smaller in DCC images than gray-scale images. These encouraging results demonstrate that characterization of nonsimple breast cysts may be improved by using DCC values from 2D elastography, which could potentially change management options of these cysts from intervention to imaging follow-up. A dedicated clinical trial to fully assess the efficacy of this technique is recommended. (E-mail: jrubin@med.umich.edu)

A comparison of radiographic signs of pulmonary inflammation during ECMO between silicon and poly-methyl pentene oxygenators

The inflammatory response caused by extracorporeal membrane oxygenation (ECMO) is clearly visible within the first 24 h of cannulation. The inflammatory process affects all areas of the lung, even areas previously spared by the primary disease. To compare the change in the radiographic signs of inflammatory response to ECMO between poly-methyl pentene and silicon oxygenators. Retrospective review of neonates and adults pre- and post-replacement of silicon oxygenators with poly-methyl pentene devices. Data were collected from Extracorporeal Life Support Organisation (ELSO) registry forms and patient records. Results were analysed by quantitative and semi-quantitative methods. There was a significant reduction in the radiographic signs of inflammatory response to ECMO, and a reduction in the time taken to revert to pre-ECMO state in the neonatal poly-methyl pentene group compared to silicon. However, there was no significant reduction in the duration of ECMO runs and the percentage survival between these groups in the neonates. In adults, there was no difference in severity of radiographic signs between groups. However, the inflammatory changes were relatively delayed in the adult poly-methyl pentene group. Polymethyl pentene (Medos) oxygenators have reduced the host's response phenomenon 'white out' in neonates, and caused a delayed response in adults. This is most likely a consequence of smaller blood contact surface area combined with the effect of heparin coating of the oxygenator membrane. However, recovery was not a function of the type of gas exchange device used.