Design and Material Characterization of an Inflatable Vaginal Dilator.

There are more than 13,000 new cases of cervical cancer each year in the United States and approximately 245,000 survivors. External beam radiation and brachytherapy are the front-line treatment modalities, and 60% of patients develop vaginal damage and constriction, i.e., stenosis of the vaginal vault, greatly impeding sexual function. The incidence of vaginal stenosis (VS) following radiotherapy (RT) for anorectal cancer is 80%. VS causes serious quality of life (QoL) and psychological issues, and while standard treatment using self-administered plastic dilators is effective, acceptance and compliance are often insufficient. Based on published patient preferences, we have pursued the design of a soft inflatable dilator for treating radiotherapy-induced vaginal stenosis (VS). The critical component of the novel device is the dilator balloon wall material, which must be compliant yet able to exert therapeutic lateral force levels. We selected a commercially available silicone elastomer and characterized its stress-strain characteristics and hyperelastic properties. These parameters were quantified using uniaxial tensile testing and digital image correlation (DIC). Dilator inflation versus internal pressure was modeled and experimentally validated in order to characterize design parameters, particularly the dilator wall thickness. Our data suggest that an inflatable silicone elastomer-based vaginal dilator warrants further development in the context of a commercially available, well-tolerated, and effective device for the graded, controlled clinical management of radiotherapy-induced VS.

Design and Validation of an Automated Dilator Prototype for the Treatment of Radiation Induced Vaginal Injury.

Vaginal stenosis (VS) is a common late complication of radiation injury caused by cervical cancer radiotherapy. It is characterized by the narrowing or shortening of the vaginal canal, which is often detrimental to patient quality of life. To address this public health problem, an expandable vaginal dilator was designed for the prevention of VS in cervical cancer survivors. Modeling and benchtop experimentation were used to iteratively characterize the relationship among dilator pressure, expansion, and the load applied to the simulated vaginal wall. Both experimental and simulation results exhibited shared trends relating pressure, dilator expansion, applied load, and resultant displacement of the modeled vaginal walls. Future work will incorporate enhanced Mooney-Rivlin material assumptions and validation of the model with in vivo tests.Clinical Relevance- These results present a design opportunity and treatment paradigm shift to increase patient adherence to VS treatment after cervical cancer radiotherapy. Specifically, gradual expansion of the vaginal dilator increases comfort during the expansion of the vagina, while monitoring the dilator pressure enables the tracking of VS improvement and normalization of vaginal wall compliance.

A comparative study of experimental urinary catheters containing silver and zinc for biofilm inhibition.

Both commercial and experimental antibacterial urinary catheters were investigated for their efficacy in preventing planktonic growth and biofilm formation of Escherichia Coli bacteria in a synthetic urine solution. Experimental antibacterial catheters having thin (<500 µm) dispersions of Ag, Ag/Ag2O, or Zn/Ag2O in polydimethylsiloxane (PDMS) binder all exhibited significant antimicrobial activity, outperforming traditional commercial antibacterial catheters. All experimental catheters prevented planktonic growth of bacteria and did not exhibit biofilm formation during a six-day test period using a colony forming unit (CFU) measurement method. On the other hand, the best performing commercial catheters demonstrated efficacy for only 3 days in planktonic growth tests and formed multiple bacterial colonies in CFU measurements. The Zn/Ag2O/PDMS experimental catheter was the only catheter observed to produce hydrogen peroxide, a reactive oxygen species known to inhibit biofilm formation; lack of detectable hydrogen peroxide production by the Ag2O/PDMS and Ag/Ag2O/PDMS experimental catheters suggests that bactericidal action most likely arises from release of silver ions present in the PDMS coatings.