Softening of Thermoplastic Polyurethanes: A Structure/Property Study

Zdrahala, Richard J.; Spielvogel, David E.; Strand, Marc A.

doi:10.1177/088532828700200403

Cited by 16 publications

(4 citation statements)

References 6 publications

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“…The softening results both from the temperature increase and the aqueous environment. The chemical composition of the biornaterial provides a material which softens in the body (5).…”

Section: Resultsmentioning

confidence: 99%

Medical grade tubing: Criteria for catheter applications

Lambert

Lee

Taller

et al. 1991

J. Vinyl Addit. Technol.

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In 1990 there were approximately 7 10 million catheter units produced worldwide from a variety of materials. This number is expected to increase 5-7% in 1991. Intravenous catheters are currently being produced from a myriad of materials including polyurethanes, polyvinylchloride, silicone rubber, and Teflon@, to name a few. Along with the ultimate end usage of a catheter, many other performance characteristics must be evaluated. Some of these characteristics are mechanical and physical properties, surface properties, hemocompatibility, biostability, and processability. The Vialon@ biomaterial has a tensile strength of 520 kg/cm2 which is over 50% higher than the other materials studied. This bioengineered material, which is a member of the broad class of polyurethanes, also gave better hemocompatibility properties, as measured by in uiuo platelet deposition. In addition Vialon@ is engineered such that the material softens in the body's moisture and heat rendering it biocompatible. The thermoplastic nature of this polymer also allows its ease of processing by such conventional means as thermal extrusion. A comparison of the aforementioned materials against these and other performance criteria was undertaken and will be presented.

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“…The softening results both from the temperature increase and the aqueous environment. The chemical composition of the biornaterial provides a material which softens in the body (5).…”

Section: Resultsmentioning

confidence: 99%

Medical grade tubing: Criteria for catheter applications

Lambert

Lee

Taller

et al. 1991

J. Vinyl Addit. Technol.

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“…Therefore, left sided catheters are often 4-6 cm longer than right sided catheters. The predominant polymer of venous access catheters, thermoplastic polyurethanes, are known to soften at body temperature, which may lead to more catheter laxity and increased migration in longer catheters [31]. A combination of these factors may be contributing to cranial migration of the catheter tip, however more research is needed to better determine why left-sided catheters tend to have a greater degree of migration and dysfunction.…”

Section: Discussionmentioning

confidence: 99%

Internal Jugular Central Venous Catheter Tip Migration: Patient and Procedural Factors

2022

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Background: The ideal central venous catheter (CVC) tip position placement is controversial, and CVCs do not remain in a fixed position after placement. This study evaluates both patient and procedural factors which may influence CVC tip migration and subsequent catheter dysfunction. Materials and Methods: This study evaluates CVC placements at a single institution. Patient age, gender, body mass index (BMI), catheter laterality, CVC type and indication for central venous access were recorded. Catheter tip location relative to the carina was measured at time of placement and removal utilizing supine fluoroscopic imaging. Patients’ electronic medical records were reviewed for evidence of catheter dysfunction. Statistical analysis was performed utilizing odds ratios and two tailed Student’s t-test. Results: 177 patients were included (101 female; mean age 55; mean BMI 29.2). Catheter types included 122 ports, 50 tunneled large bore central venous catheters (≥9 French), and 5 tunneled small bore central venous catheters (<9 French). 127 were right sided catheters, and 50 were left sided. Left sided CVCs had a mean cranial tip migration of 3.2 cm (standard deviation ±2.9 cm) compared to 0.8 cm (standard deviation ±1.9 cm) for right sided catheters (p = 0.000008). Catheters that migrated cranially by >2 cm had more than 7× greater risk of dysfunction compared to catheters that migrated ≤2 cm (odds ratio of 7.2; p = 0.0001). Left sided CVCs were significantly more likely to have >2 cm of cranial migration (odds ratio 6.9, 95% CI 3.4–14.2, p < 0.0001) and had a higher rate of dysfunction, likely due to this cranial migration (32% vs. 4.7%; p = 0.00001). Gender and BMI were not found to be associated with catheter dysfunction or an increased odds ratio of >2 cm cranial migration. Conclusions: Left-sided CVCs migrate an average of 2.4 cm cranially more than right-sided catheters. Additionally, when migration occurs, left-sided catheters are more likely to be dysfunctional. These suggest that lower initial placement may be beneficial in left-sided catheters.

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“…During retraction in the dry state, it is possible that the energy stored in the hard crystalline domains is responsible for retraction while the energy stored in the amorphous domains is dissipated, thereby leading to a large hysteresis area. In the wet state, the energy consumed for compressing the amorphous domains might be minimized due to the plasticizing effect of water in the amorphous domains and the interface of the amorphous and hard domains [58]. The retraction of the wet ring still might be due to the energy stored in the hard domains similar to the dry ring, thereby leading to similar force during retraction as in the dry state and lower hysteresis as compared to the dry IVR.…”

Section: Discussionmentioning

confidence: 99%

Engineering a degradable polyurethane intravaginal ring for sustained delivery of dapivirine

Kaur

Gupta

Poursaid

et al. 2011

Drug Deliv. and Transl. Res.

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We describe the engineering of a degradable intravaginal ring (IVR) for the delivery of the potent HIV-1 reverse transcriptase inhibitor dapivirine. The degradable polymer used in fabricating the device incorporated poly(caprolactone) ester blocks in a poly(tetramethylene ether) glycol ABA type polyurethane backbone. The polymer was designed to maintain its structure for 1 month during usage and then degrade in the environment post-disposal. In vitro release of dapivirine showed zero-order kinetics for up to 1 month and significant levels of drug release into engineered vaginal tissue. The mechanical properties of the degradable IVR were comparable to those of a widely used contraceptive intravaginal ring upon exposure to simulated vaginal conditions. Incubation under simulated vaginal conditions for a month caused minimal degradation with minimal effect on the mechanical properties of the ring and polymer. The cytotoxicity evaluation of the drug-loaded IVRs against Vk2/E6E7 human vaginal epithelial cells, Lactobacillus jensenii, and engineered vaginal tissue constructs showed the degradable polyurethane to be non-toxic. In vitro evaluation of inflammatory potential monitored through the levels of inflammatory cytokines IL-8, IL-1α, IL-6, IL-1β, and MIP-3α when engineered EpiVaginal™ tissue was incubated with the polyurethanes suggested that the degradable polyurethane was comparable to commercial medical grade polyurethane. These results are encouraging for further development of this degradable IVR for topical vaginal delivery of microbicides.

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Softening of Thermoplastic Polyurethanes: A Structure/Property Study

Cited by 16 publications

References 6 publications

Medical grade tubing: Criteria for catheter applications

Medical grade tubing: Criteria for catheter applications

Internal Jugular Central Venous Catheter Tip Migration: Patient and Procedural Factors

Engineering a degradable polyurethane intravaginal ring for sustained delivery of dapivirine

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