A Novel Semi-quantitative In Vitro Evaluation of Gelling Fiber Dressings: The Microcontouring Method

The ability of a dressing to adapt to the wound surface upon hydration is critical for maintaining a moist wound-healing environment and for minimizing any "dead space" between the dressing and the wound surface, where pathogens may proliferate. This ability to conform to a surface can be affected by many factors, including (but not limited to) dressing composition, fiber directionality, and any additional features, such as strengthening stitches, additional layers, or welding. Gelling fiber dressings, such as those composed of sodium carboxymethylcellulose, form a gel upon hydration, promoting a moist healing environment and sequestering harmful wound components. However, there is currently no standardized method to assess a dressing's ability to conform to contoured wound surfaces. This technical report describes a novel in vitro method (referred to as the microcontouring method) to semi-quantitatively evaluate dressing conformity. A 3D-printed test rig with a contoured sample platform and integrated fluid port was developed. Samples of one type of carboxymethyl-cellulose-based gelling fiber dressing were hydrated with isotonic simulated wound fluid under controlled conditions (n=13). Time-lapse video and endpoint still images were captured to assess dressing behavior and quantify residual "dead space" (measured area of gaps between sample and rig surface) using ImageJ software (Bethesda, MD: National Institutes of Health). The method demonstrated strong reproducibility, with a coefficient of variation below 10% across three analysts. The setup enabled clear visualization of hydration dynamics and allowed for semi-quantitative comparison between samples. The microcontouring method provides a reproducible, semi-quantitative approach for evaluating the conformability of gelling fiber dressings. While further work is required to determine reproducibility across a wider range of gelling fiber dressings, this proof-of-principle work offers a potentially valuable tool for product development and comparative testing, addressing a current gap in standardized assessment techniques.