A Methodology for Assessing Pressure Redistribution of Advanced Wound Care Dressings at Clinically Relevant Loads

Martha Roman, Anthony Frei PhD

RESULTSThree commercially available dressings were assessed for peak contactpressure redistribution. At 8kPa, Dressing A yielded a reduction in peakcontact pressure of 58%, whereas Dressing B and C yielded reductions inpeak contact pressure of 52% and 46% respectively (Figure 2). At 18kPa,Dressing A yielded a reduction in peak contact pressure of 34%, whereasDressing B and C yielded reductions in peak contact pressure of 20% and19% respectively (Figure 3).

Figure 2: Percentage reduction in peak contact pressure at 8kPa relative to no dressing

Figure 3: Percentage reduction in peak contact pressure at 18kPa relative to no dressing

© 2021 Medline Industries, Inc. All rights reserved.

High Pressure

Calibrated Pressure KPa

Low Pressure

Fabricated Weight

Subcutaneous Fat & Flesh Analogue

Silicone Skin Analogue

Wound Dressing (adhered to skin analogue)

Tekscan ™ Conformat

MEASURING PRESSURE – Tekscan™ Conformat

This study used the Tekscan™ Conformat sensor system, this system isbuilt in a modular sensor construct and has the ability to measure spatialresolutions as fine as one sensing element per square centimeter. TheTekscan™ Conformat is thin and flexible and able to conform to complexsurfaces making it uniquely suited to measure pressure at loaded humaninterfaces4.

METHODOLOGY

A novel laboratory test method was developed, featuring the Tekscan™Conformat, a subcutaneous fat/flesh analogue and a silicone skinanalogue (used to mimic the mechanical cushioning properties of humanflesh and skin). Commercially available wound dressings were thenadhered to the underside of the skin analogue, fabricated weights wereplaced on the outer surface of the flesh analogue (Figure 1). This novelexperimental set up mimics the effects of pressure typically seen overbony prominences (areas of high risk of developing pressure injuries), byapplying pressure to the underside of the wound dressing.

The weights were fabricated to apply a sustained load at clinicallyrelevant levels of pressure of either 8kPa (maximum sacral pressure whenpatient is laid in the supine position in a hospital bed5) or 18kPa(maximum sacral pressure recorded when a patient is sat in a wheelchairwith feet at rest6).

Three commercially available wound dressings (Dressing A, B & C) were then assessed using this test method.

Figure 1: a typical experimental set up for dressing testing (illustration and not to scale).

PRESSURE MAPPING IMAGESPressure Mapping at 8kPa Load

Pressure Mapping at 18kPa Load

Dressing A Dressing B Dressing C

Dressing A Dressing B Dressing C

BACKGROUNDThe 2019 NPIAP Guidelines for Prevention andTreatment of Pressure Injuries emphasized theimportance of pressure and sustained load1. TheNPIAP guidelines also identified that the sacrum is themost common anatomical area for developing severepressure injuries2,3.

“Pressure Injuries are defined as localized damage toskin or underlying tissue as a result of pressure mostcommonly occurring over bony prominences”

Multilayer silicone foam dressings have been provento be effective at reducing the prevalence of pressureinjuries1 and are increasingly used as part of apressure injury prevention protocol of care.

INTRODUCTION

Can multilayered silicone foam dressings redistributepressure at clinically relevant pressures?

It is widely recognized that one of the keycontributing factors to pressure injury occurrence isthe deformation of skin and underlying tissue asresult of direct sustained load. However, there are fewin vitro test methods that can accurately measuresuch forces at clinically relevant levels. This, in turn,limits the ability to assess the relative pressureredistribution properties of wound dressings.

The goal of this study was to establish a test methodthat could assess the pressure redistributionproperties of various commercially available wounddressing, when exposed to clinically relevant loading.

CONCLUSIONThis in vitro study assessed the relative effectivenessof various commercially available wound dressing'sability to reduce pressure transmitted to a patient'sskin. The higher the percentage reduction in peakpressure, the better the dressings have buffered thisforce, and the more effective the dressing is atcushioning and redistributing pressure. Overall,Dressing A showed the largest reduction in pressure incomparison to no dressing, outperforming bothDressings B & C.

In the future, this methodology may permit cliniciansto have a greater understanding of the pressureredistribution properties of wound care dressings, andhow these dressings can be used as part of a pressureinjury prevention protocol.

REFERENCES

1. National Pressure Injury Advisory Panel. Prevention and Treatment of Pressure Ulcers/Injuries: Clinical Practice Guideline. The International Guideline 2019

2. Vander K, Clark M, Dealy C, Gunningberg L, Defloor T. Pressure ulcers prevalence in Europe: A pilot study J Eval Clin Pract, 2007; 13 (2): 227 – 232

3. Barrois B, Colin D, Allaert FA. Prevalence, characteristics and risk factors of pressure ulcers in public and private hospital care units and nursing homes in France. Hosp Pract, 2018: 15:15

4. Hooper, R., Jones, G. (Department of Human Sciences, Loughborough University) "Are Interface Pressure Measurements a True Reflection of Skin Contact Pressure when over Different Layers of Clothing?"

5. Goossens RH, Snijders CJ, Holscher TG, Heerens WC, Holman AE. Shear stress measured on bed and wheelchairs. Scand J Rehabil Med. 1997 Sep;29(3):131-6.

6. Lindan O, Greenway RM. Piazza JM. Pressure distribution on the surface of the human body. I. Evaluation in lying and sitting positions using a “bed of springs and nails.” Arch Phys Med Rehabil. 1965;46:378.)

Dressing A: Optifoam Gentle SA™ (Medline Industries, Inc.)Dressing B: Mepilex Border ™ (Mölnlycke)Dressing C: Allevyn Life™ (Smith & Nephew)

© 2021 Medline Industries, Inc. All rights reserved. 19W1766105 / e21207