of the data from dressing A is also significantly lower than for ... Determination of the coefficient of friction [Data
Friction and hydrocolloid dressings, a comparative in-vitro study C. Toxvaerd, Coloplast A/S, M. Khalesi Coloplast A/S and M. Rathe Coloplast Canada Corp. Wounds Canada Spring Conference, Winnipeg 2018
Introduction
It is important to protect newly formed skin or stage I and II pressure ulcers from friction and shear to help reduce (further) skin breakdown. Thin hydrocolloid dressings with smooth top films can help reduce the friction-coefficient1 and a low friction top film (or backing) then becomes an important feature of thin hydrocolloid dressings. Inspired by this clinical significance, we have evaluated hydrocolloid dressings from 2 different manufacturers on dynamic and static friction parameters The friction of dressing A* was benchmarked against dressings B* and C*. The objective was to assess surface friction in a typical clinical setting, where the top film is in contact with textile, for instance bed linen or clothing.
Method of testing
Testing was conducted at an external lab and was accomplished as per procedure DS/EN ISO 8295:2004 Plastics – Film and sheeting – Determination of the Coefficient of
Friction (CoF)2. The test measures the force needed to pull a sleigh over a test surface. In our setting, the moving sleigh was covered by the test dressings, and a cotton textile was used as the test surface3. In this way, the cotton textile simulating the bed linen would be in direct contact with the surface of the dressing covering the wound. The Coefficient of Friction (CoF) is calculated by dividing the force needed to move the sleigh, by the gravitational force of the sleigh. The results are given as static Coefficient of Friction COFs and dynamic Coefficient of Friction CoFd: The static CoFs is the measurement of the friction between two or more solid objects that are not moving relative to each other and is normally higher than the dynamic CoFd, which is the CoF when the sample is in motion. This would reflect a clinical environment where a patient is repositioned or moved. Test products are; three batches of dressing A, two batches of dressing B and one batch of C.
Results
Discussion
See Figure 1 and 2.
The result may be an indicator that dressing A has a positive effect in lowering friction and shear compared to dressings B and C.
The CoFs and CoFd of dressing A is at the same level, and approximately 40% or less than the CoFs and CoFd of dressings B and C. The Relative Standard Deviation (RSD%) of the data from dressing A is also significantly lower than for dressings B and C, indicating less variation in quality for dressing A.
The friction caused by the surface of the top film and a textile such as duvet cover or clothes can be measured by this test method and we found different values for the test products of dressing A and dressing B and C.
Dynamic CoefficientofofFriction Friction (CoFd) (CoFd) Dynamic Coefficient 1,80 1,60 1,40
1,80
1,80
1,60
1,60
1,40
1,40
1,20
1,80 1,60 1,40 1,20
1,20 1,00
1,00 0,80
1,00 0,80
0,80 0,60
0,80 0,60
0,40 0,20 0,00
0,60
0,20
0,40
0,00
A
A
B
B
C
0,20
C
0,00
Dressing A displays a significantly lower coefficient of friction than dressings B and C. Thus, dressing A should be better at reducing friction at the patient-support interface.
Static Coefficient Friction (CoFs) (CoFs) Static Coefficient ofofFriction
1,20 1,00
0,60 0,40
Conclusion
References: 1. Fletcher et al, 2011 “Pressure ulcers and hydrocolloids – Made Easy”, Wounds International, vol. 2, issue 4, Nov 2011 2. DS/EN ISO 8295:2004 Plastics – Film and Sheeting – Determination of the coefficient of friction [Data on file] 3. DTI test report no. 157/17, June 2017 [Data on file] A. Comfeel® Transparent Plus, B. DuoDerm® Extra Thin, C. VariHesive® Extra Dünn
0,40 0,20 0,00
A
A
B
B
C
C
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