Clinical and Economic Impact of Wound Care Using a Polyurethane Foam Multilayer Dressing.

OBJECTIVE: To study the impact of a newly introduced dressing on efficiency and quality of care in routine clinical practice in a Spanish community setting. DESIGN AND SETTING: An ambispective multicenter observational study was conducted in 24 primary care centers and 6 nursing homes in 4 different Spanish regions. The study was carried out between November 2017 and March 2019. PATIENTS AND INTERVENTION: A total of 128 wounds in 94 patients (primary care, n = 79; nursing home, n = 15) were analyzed before and 4 weeks after switching to the study dressing. OUTCOME MEASURES: Frequency of dressing changes; secondary outcomes were change in the mean wound area and weekly cost and patient and provider satisfaction. MAIN RESULTS: The mean number of dressing changes was significantly reduced with the study dressing from 3.14 ± 1.77 changes per week to 1.66 ± 0.87 (P < .001), a 47.1% reduction in frequency. Wound area significantly reduced from 9.90 ± 19.62 cm to 7.10 ± 24.33 cm. In addition, a 58.7% reduction in weekly costs was achieved with the intervention. Patients and providers agreed that their satisfaction with wound care improved. CONCLUSIONS: The use of the study dressing in routine clinical practice could lead to a major improvement in both efficiency and quality of wound care. Its use could reduce wound care-related costs through improvements in healing and a reduced frequency of dressing changes. It also enhanced the wound care experience from the perspective of both patients and providers.

On site comparison of the OSHA 42, Asset EZ4-NCO, Iso-Chek, DAN and CIP10 methods for measuring toluene diisocyanate (TDI) at a polyurethane foam factory.

Because of the semi-volatile nature of diisocyanates (being airborne in both physical vapor and particulate phases), their high reactivity and low occupational exposure limits, diisocyanate exposure evaluation has been challenging for industrial hygienists and laboratories. The objective of this study was to compare the toluene diisocyanate (2,4 and 2,6 isomers, TDI) concentration measured by five methods in a flexible polyurethane foam factory using different collection or derivatization approaches. The methods used were: OSHA 42 modified (filter, 1-(2-pyridyl)piperazine) (OSHA), Asset EZ4-NCO (denuder and filter, dibutylamine) (Asset), Iso-Chek (double-filter, 9-(N-methylaminomethyl) anthracene and 1,2-methoxyphenylpiperazine), DAN (filter, 1,8-diaminonaphthalene), and CIP10 (centrifugation, 1,2-methoxyphenylpiperazine). Particle real-time monitoring for concentration and size distribution was performed in parallel to improve the understanding of the potential bias between methods. The comparison study was performed over 3 days, providing 18 replicates for each of the 5 methods. Isocyanate concentrations collected for each sampling method were compared using linear mixed effect modeling. Compared to OSHA, which yielded the highest concentrations overall, the Asset and DAN methods provided the smallest biases (-29% (95% CI [-52;-6]) and -45% (95% CI [-67;-23]), respectively), while the CIP10 and Iso-Chek methods provided the largest biases (-82% (95% CI [-105;-66]) and -96% (95% CI [-118;-75]), respectively). The substantial bias of Iso-Chek and CIP10 seemed to be explained by the predominance of TDI in the form of sub-micron particles that were inadequately captured by these two methods due to their sampling principle, which are particle filtration without derivatizing agent and centrifugation respectively. Asset and DAN performance seemed to decrease as the sampling time increased. While DAN's bias could be related to a reagent deficiency on the filter, the disparities between OSHA and Asset, both considered as reference methods, highlight the fact that the mechanisms of collection, derivation and extraction do not seem to be completely controlled. Finally, an upward trend has been observed between concentrations of particles below 300 nm in size and concentration levels of TDI. It has also been observed that TDI levels increased with the TDI foam index produced at the facility.

Absorption Capacity of Wound Dressings: A Comparative Experimental Study.

In this study, absorption capacity of the most commonly used types of wound dressings was measured with an objective, quantifiable, and easily reproducible method. The use of objective measurements allowed us to perform an objective comparison of the capacity of the different types of dressings. An experimental study was performed, in which the absorptive capacity of polyurethane foams, alginate, hidrofiber, and hydrocolloid dressings was measured by using a methodology designed by the researchers. Polyurethane foams showed a higher absorption capacity than hidrofibers, alginates, and hydrocolloids when using a similar surface of dressing. A modification of dressing size after saturation was also observed, increasing its size in the case of foams and decreasing or maintaining it in the case of hidrofibers, alginates, and hydrocolloids. The results of this study show a better wound exudate management for polyurethane foams. However, when deciding which dressing to use for a specific wound, absorption capacity is not the only quality that should be taken into account, as other properties should also be considered.

Estimation of the Human Extrathoracic Deposition Fraction of Inhaled Particles Using a Polyurethane Foam Collection Substrate in an IOM Sampler.

Extrathoracic deposition of inhaled particles (i.e., in the head and throat) is an important exposure route for many hazardous materials. Current best practices for exposure assessment of aerosols in the workplace involve particle size selective sampling methods based on particle penetration into the human respiratory tract (i.e., inhalable or respirable sampling). However, the International Organization for Standardization (ISO) has recently adopted particle deposition sampling conventions (ISO 13138), including conventions for extrathoracic (ET) deposition into the anterior nasal passage (ET1) and the posterior nasal and oral passages (ET2). For this study, polyurethane foam was used as a collection substrate inside an inhalable aerosol sampler to provide an estimate of extrathoracic particle deposition. Aerosols of fused aluminum oxide (five sizes, 4.9 µm-44.3 µm) were used as a test dust in a low speed (0.2 m/s) wind tunnel. Samplers were placed on a rotating mannequin inside the wind tunnel to simulate orientation-averaged personal sampling. Collection efficiency data for the foam insert matched well to the extrathoracic deposition convention for the particle sizes tested. The concept of using a foam insert to match a particle deposition sampling convention was explored in this study and shows promise for future use as a sampling device.

The impact of culture medium on the development and physiology of biofilms of Pseudomonas fluorescens formed on polyurethane paint.

Microbial biofilms cause the deterioration of polymeric coatings such as polyurethanes (PUs). In many cases, microbes have been shown to use the PU as a nutrient source. The interaction between biofilms and nutritive substrata is complex, since both the medium and the substratum can provide nutrients that affect biofilm formation and biodeterioration. Historically, studies of PU biodeterioration have monitored the planktonic cells in the medium surrounding the material, not the biofilm. This study monitored planktonic and biofilm cell counts, and biofilm morphology, in long-term growth experiments conducted with Pseudomonas fluorescens under different nutrient conditions. Nutrients affected planktonic and biofilm cell numbers differently, and neither was representative of the system as a whole. Microscopic examination of the biofilm revealed the presence of intracellular storage granules in biofilms grown in M9 but not yeast extract salts medium. These granules are indicative of nutrient limitation and/or entry into stationary phase, which may impact the biodegradative capability of the biofilm.

Efficacy of a polyurethane dressing versus a soft silicone sheet on hypertrophic scars.

OBJECTIVE: To compare the efficacy and safety of a polyurethane dressing with a silicone sheet in the treatment of hypertrophic scars. METHOD: Sixty patients participated in this intra-individual 12-week clinical trial. Each scar was divided into two areas, to which the polyurethane dressing and the silicone sheet were randomly allocated. The primary outcome measure was the percentage change in the overall scar index (SI) between baseline and week 12. Secondary outcome measures included changes in skin redness, objectively measured by chromametry, and patients views on the aesthetic outcome of treatment. RESULTS: Both therapies achieved favourable results for all of the above outcome measures. Results were comparable for the primary outcome measure: 29.4% versus 33.7% for the silicone sheet and polyurethane product respectively. The decrease in the overall SI was significantly more pronounced for the polyurethane product after week 4 (5.6% versus 15.8% for the silicone sheet; p<0.0001) and week 8 (20.2% versus 27.1%; p=0.012). CONCLUSION: Both regimens were associated with a significant reduction in the clinical signs of hypertrophic scars over 12 weeks of treatment. The polyurethane dressing demonstrated a significantly more pronounced reduction in severity of these clinical signs after four and eight weeks of treatment and was better tolerated than the silicone sheet. l DECLARATION OF INTEREST: This study was funded by Beiersdorf AG. proDERM is an independent research company, and none of the authors have an interest in the sponsors commercial activities.

In vitro degradation of a biodegradable polyurethane foam, based on 1,4-butanediisocyanate: a three-year study at physiological and elevated temperature.

Biodegradable polyesterurethanes (PUs) may be used as scaffold materials for tissue regeneration applications, because of their excellent mechanical properties. In this study, the degradation of highly porous PU foams was evaluated in vitro. The PU had amorphous soft segments of DL-lactide/epsilon-caprolactone and uniform hard segments, synthesized from 1,4-butanediisocyanate and butanediol. The foams were degraded for 3 years in a Sörensen buffer solution (pH 7.4) at 37 and 60 degrees C. Dimensions of the foams, intrinsic viscosity, mass loss, thermal properties, and composition of the remaining material were evaluated. Copolyester (CP) foams of DL-lactide/epsilon-caprolactone served as controls. The PU foams kept their dimensions for 20 weeks at 37 degrees C, whereas CP foams collapsed after 3 weeks. PU mass loss reached a maximum of 80% at both 37 and 60 degrees C. CP mass loss reached 99.9% at 60 degrees , and 92% at 37 degrees C after 3 years. The degradation processes at 37 and 60 degrees C are initially the same, but eventually degradation products with different thermal properties are being formed. (1)H NMR studies showed that the hard urethane segments of the PU do not degrade in vitro at pH 7.4. It was concluded that the PU material has favorable characteristics for a scaffold material. Compared to long-term in vivo results of the same PU these in vitro results are not representative for the in vivo situation and therefore total resorption has to be investigated in long-term in vivo studies.

Compressive properties of commercially available polyurethane foams as mechanical models for osteoporotic human cancellous bone.

BACKGROUND: Polyurethane (PU) foam is widely used as a model for cancellous bone. The higher density foams are used as standard biomechanical test materials, but none of the low density PU foams are universally accepted as models for osteoporotic (OP) bone. The aim of this study was to determine whether low density PU foam might be suitable for mimicking human OP cancellous bone. METHODS: Quasi-static compression tests were performed on PU foam cylinders of different lengths (3.9 and 7.7 mm) and of different densities (0.09, 0.16 and 0.32 g cm(-3)), to determine the Young's modulus, yield strength and energy absorbed to yield. RESULTS: Young's modulus values were 0.08-0.93 MPa for the 0.09 g cm(-3) foam and from 15.1-151.4 MPa for the 0.16 and 0.32 g cm(-3) foam. Yield strength values were 0.01-0.07 MPa for the 0.09 g cm(-3) foam and from 0.9-4.5 MPa for the 0.16 and 0.32 g cm(-3) foam. The energy absorbed to yield was found to be negligible for all foam cylinders. CONCLUSION: Based on these results, it is concluded that 0.16 g cm(-3) PU foam may prove to be suitable as an OP cancellous bone model when fracture stress, but not energy dissipation, is of concern.

[Shape-memory polymers for biomedical engineering applications].

The latest progress in shape-memory polymer for biomedical engineering applications was summarized in this paper. The mechanism responsible for shape memory effect was analyzed in reference to the polymer structure. Also introduced and reviewed were the characteristics of some shape-memory polymers (polyurethane polycaprolactone and polylactide) and their applications in medical engineering.

Comparison of linear-linear and hyperbranched-linear dental composite.

Linear polymers have been commonly used as dental composite. However the aim of this work is to use hyperbranched polymer in an attempt to produce dental composite. The reason is because the dendritic molecules have shown low viscosity at higher molecular weight compared to the linear counterparts. Therefore, this work attempts to substitute the linear polymer with as much of hyperbranched polymer in the dental composite that would pass the required ISO 4049:1998(E) "Dentistry - Resin-based filling material". Several formulations of dental composites were used, i.e. combinations of linear-linear and linear-hyperbranched polymers for comparison. Following this, physical and mechanical characterisation were conducted based on the ISO standards such as water sorption and water solubility. Other characterisation such as polymerisation shrinkage and Vickers hardness were also evaluated. It was found that different types of resins give different physical and mechanical properties. The maximum achievable hyperbranched polymer, which passes the required ISO standard, that can be incorporated in the linear polymer to form dental composite is 43% wt.

Parental satisfaction with bonded resin composite strip crowns for primary incisors.

PURPOSE: The purpose of this study was to evaluate the parental satisfaction of bonded resin composite strip crowns for the treatment of maxillary anterior primary incisors and compare their satisfaction with the clinical evaluation and success of the crowns. METHODS: This was a retrospective, clinical study of patients who had strip crowns (SC) placed on maxillary primary incisors, returned for at least 1 recall examination, and whose parents gave consent for them to participate in the study. Color photographs were used for evaluation by 2 independent pediatric dentists. Parental satisfaction regarding the esthetics of the crowns was evaluated by a questionnaire. RESULTS: One hundred and twelve restorations placed in 40 children were evaluated. The evaluations were performed after the crowns had been in place for an average of 18 months (range=6-25 months). Overall parental satisfaction with the treatment was excellent; however, satisfaction with regard to color received the lowest rating. No significant differences were found between dentist and parent evaluations of color, size, and overall appearance (Fisher exact test; P=.194,.776,.291, respectively). Parents rated their overall satisfaction as being positive regardless of their poor ratings of color, size, or overall appearance. However, a significant relationship was found between durability and overall satisfaction (P=.046). Parents who gave poor ratings to durability also rated their overall satisfaction as being poor. CONCLUSIONS: Parental satisfaction with bonded resin composite SCs for the treatment of primary incisors with large or multi-surface caries was excellent. Parents' dissatisfaction was most often related to color of the restorations. However, this did not affect their overall satisfaction with the crowns. The durability of restorations negatively affected the rating of overall satisfaction with the crown. Durability seems to be of more concern than excellent color match to this group of parents.

Why we can't believe what we read.

It is argued that many claims made in the dental literature lack scientific grounding. Rather than become cynical, dentists are urged to use their own critical judgment and caution when reading the literature, especially articles and advertisements in the rapidly expanding area of dental materials. An example involving research on "condensable" resin-bonded composites is analyzed in detail, showing how an apparently credible claim can be lacking in support.

Randomized clinical trial comparing 2 support surfaces: results of the Prevention of Pressure Ulcers Study.

OBJECTIVE: To determine whether a viscoelastic polymer (energy absorbing) foam mattress was superior to a standard hospital mattress for pressure ulcer prevention and to analyze the cost-effectiveness in comparison with standard hospital mattresses. DESIGN: Unblinded, randomized, prospective trial. SETTING: Elderly acute care, rehabilitation, and orthopedic wards at 3 hospitals in the United Kingdom. PARTICIPANTS: 1168 patients at risk of developing pressure ulcers (Waterlow score, 15 to 20), with a median age of 83 years (25th to 75th percentile range, 79-87). INTERVENTIONS: Participants were allocated to either the experimental equipment (CONFOR-Med mattress/cushion combination) or a standard mattress/cushion combination; all were given standard nursing care. Pressure areas were observed daily. MAIN OUTCOME MEASURE: Development of nonblanching erythema. RESULTS: A significant decrease in the incidence of blanching erythema (26.3% to 19.9%; P =.004) and a nonsignificant decrease in the incidence of nonblanching erythema occurred in participants allocated to the experimental equipment. However, when the survival curve plots were analyzed at 7 days, both categories showed statistically significant decreases (P =.0015 and P =.042, respectively). Participants on standard equipment had a relative odds ratio of 1.36 (95% confidence interval [CI], 1.10-1.69) for developing blanching erythema or worse and 1.46 (95% CI, 0.90-1.82) for developing nonblanching erythema or worse. To prevent nonblanching erythema, the number needed to treat (NNT) was 41.9 (95% CI, -82.6-15.3). To prevent any erythema (blanching or nonblanching), the NNT was 11.5 (95% CI, 41.6-9.3). Participants with blanching or nonblanching erythema were significantly less mobile than participants with normal skin and more likely to have worsening mobility (P <.001). For participants with similar pressure ulcer status, mattress type was not associated with difference in mobility. CONCLUSIONS: Regardless of prevention routine, pressure ulcers occur. In this study, the experimental equipment showed statistical significance to standard equipment for prevention of blanching erythema; significance was not achieved for nonblanching erythema. Trend and survival analysis show that a larger study is required to determine whether this nonsignificant difference is genuine.

Long-term quantification of the release of monomers from dental resin composites and a resin-modified glass ionomer cement.

This study quantified the release of monomers from polymerized specimens of four commercially available resin composites and one glass ionomer cement immersed in water:ethanol solutions. Individual standard curves were prepared from five monomers: (1) triethylene glycol dimethacrylate (TEGDMA), (2) 2-hydroxy-ethyl methacrylate (HEMA), (3) urethane dimethacrylate (UDMA), (4) bisphenol A glycidyl dimethacrylate (BISGMA), and (5) bisphenol A. The concentration of the monomers was determined at Days 1, 7, 30, and 90 with the use of electrospray ionization/mass spectrometry. Data were expressed in mean micromol per mm(2) surface area of specimen and analyzed with Scheffe's test (p<0.05). The following monomers were found in water: monomers (1) and (2) from Delton sealant, monomer (5) from ScotchBond Multipurpose Adhesive and Delton sealant, monomer (3) from Definite and monomer (4) from Fuji II LC, ScotchBond Multipurpose Adhesive, Synergy and Definite. All these monomers increased in concentration over time, with the exception of monomer (1) from Delton sealant. Monomers (3) and (5) were found in extracts of materials despite their absence from the manufacturer's published composition. All monomers were released in significantly higher concentrations in water:ethanol solutions than in water. The greatest release of monomers occurred in the first day. The effect of the measured concentrations of monomers (1-5) on human genes, cells, or tissues needs to be considered with the use of a biological model.

Lactic acid based PEU/HA and PEU/BCP composites: Dynamic mechanical characterization of hydrolysis.

Lactic acid based poly(ester-urethane) (PEU-BDI) and its composites with 20 and 40 vol.% bioceramic filler were characterized prior to their use as biocompatible and bioabsorbable artificial bone materials. Morphological, dynamic mechanical properties, and degradation of these either hydroxyapatite or biphasic calcium phosphate containing composites were determined. Addition of particulate bioactive filler increased the composite stiffness and the glass transition temperature, indicating strong interactions between the filler and matrix. Materials were sterilized by gamma-irradiation, which reduced the average molecular weights by 30-40%. However, dynamic mechanical properties were not significantly affected by irradiation. Specimens were immersed in 0.85 w/v saline at 37 degrees C for 5 weeks, and changes in molecular weights, mass, water absorption, and dynamic mechanical properties were recorded. All the composite materials showed promising dynamic mechanical performance over the 5 weeks of hydrolysis. Average molecular weights of PEU-BDI and its composites did not change substantially during the test period. PEU-BDI retained its modulus values relatively well, and although the moduli of the composite materials were much higher, especially at high filler content, they exhibited faster loss of mechanical integrity.

An in-vitro study of the pressure-relieving properties of four wound dressings for foot ulcers.

This in-vitro study reports on a selection of mechanical tests on four wound dressings: Allevyn (Smith and Nephew), Biatain (Coloplast), Lyofoam (Seton Scholl) and Tielle (Johnson and Johnson). The aim of the study was to investigate these dressings in the laboratory by subjecting them to dry and wet compression tests, shearing tests and a cyclical test. As predicted, all dressings performed differently in the range of tests, with Lyofoam deforming the most when subjected to compression testing (5.6 mm). During wet compression, differences in the physical properties of all the materials tested were identified. During shearing testin, Allevyn and Tielle withstood the greatest shear deflection before failure, but Biatain withstood the greatest force before failing. During the cyclical testing, Lyofoam only reduced by 1% of its original thickness, while Biatain reduced by 30%. No one dressing performed better in all the tests. However, as an all-round 'pressure-relieving' dressing, Allevyn consistently outperformed the others in the study.

The influence of four wound dressings on the kinetics of human walking.

OBJECTIVES: This in vivo study (the second phase of a research project first described in the February issue of Journal of Wound Care) reports on the influence of various wound dressings on the dynamics of human walking. Allevyn (Smith and Nephew), Biatain (Coloplast), Lyofoam (Seton Scholl) and Tielle (Johnson and Johnson) were used in this study. The investigation aimed to assess the ground reaction forces in the foot while the dressings were applied to the plantar surface of the foot. METHOD: A strain gauge force plate system was used. Six subjects with 'normal' gait patterns and no foot pathology were recruited into the study. Eight trials were recorded for each subject. The peak push-off force, in the vertical component of the ground reaction force, and the maximum braking and propulsive forces in the medial-lateral component of the ground reaction force were estimated and reported. RESULTS: Among the various dressings tested, Allevyn performed closest to barefoot in the peak push-off force and demonstrated an increased braking force at the deceleration point in the gait cycle. CONCLUSION: These findings may have implications for clinicians selecting wound dressings for the treatment of certain foot ulcerations. However, further clinical research is warranted in this area.

Retention of supportive properties by eggcrate and foam wheelchair cushions.

This study investigated the reported lack of ability of the eggcrate cushion (EC) to provide wheelchair users with adequate support necessary for comfort and tolerably low-peak sitting pressures over time. The primary parameter used to quantify the ability of the cushion to distribute load was the indention force deflection (IFD) metric. The EC was compared to a high-density planar foam cushion (HD). The IFD was measured for both cushions after successive periods of compression to simulate use. Study results failed to support the common perception that the soft EC would lose its supportive properties more rapidly than the much firmer HD cushion. Although the initial IFD of the EC was much lower than that of the HD, a smaller percentage of its IFD was lost after compression. This difference between the two cushions likely was due to differences in packaging. The EC was rolled into a cylinder, compressing it to 60% of its original thickness; the HD was packaged without compression.

A capillary method to measure water transmission through polyurethane membranes.

A capillary method has been developed to measure the rate of water transmission through polyurethane membranes prepared for use as ventricles in artificial hearts. The system consisted primarily of a leak-proof sample chamber containing the water, a glass capillary flow meter, and a receiver compartment with continuous dry air ventilation. The capillary flow meter monitored the volume of water loss in the sample chamber. The rate of water transmission through the test membrane was found to be proportional to the water loss in the sample chamber, and dependent on the membrane thickness. For thicknesses from 0.09 mm to 0.34 mm, water vapor transmission rates ranged from 7.53 x 10(-8) to 2.76 x 10(-8) mol/s cm2, respectively. Although the concentration of water vapor in the receiver compartment did affect the rate of water vapor transmission through the membrane, within the pressure range 50-200 mmHg, there was very little effect. These findings suggest that water transmission through a polyurethane membrane is dominated by a diffusion process rather than by bulk convection.

Development of the undulation pump total artificial heart.

The undulation pump is a small size continuous flow displacement type blood pump that has been developed for an artificial heart. Using undulation pumps, 2 types of implantable total artificial hearts (TAHs), the undulation pump TAH (UPTAH) type 1 (UPTAH 1) and UPTAH type 2 (UPTAH 2) were developed. Both UPTAHs were designed to be small enough to implant into the chest of a goat, the experimental animal. UPTAH 1 could be reduced in size to 75 mm in diameter and 78 mm in length. The weight was 520 g. UPTAH 2 could be reduced in size to 75 mm in diameter and 80 mm in length. The weight was 650 g. UPTAH 2 could be tested in an animal experiment using an adult female goat weighing 52.3 kg. The UPTAH 2 could be implanted successfully into the goat's chest with a good fit. The goat stood after the surgery and extubation and survived for 3 h and 40 min; thus, the potential of the UPTAH for a practical implantable TAH was demonstrated.