Applied Science and Engineering of Wound Dressings and their Clinical Effectiveness

Part 1a: Introduction: An evidence-based, clinically relevant approach to dressing design and evaluation

1. Clinical wound care and management translated to the requirements from effective wound dressings

1.1. Condensed review of the history of wound dressing materials and structures

1.2. The primary clinical roles of dressings and their relationship and contribution to wound healing

1.3. How the most clinically-relevant characteristics of dressings relate to their physical structure

1.4. Exudate management and dressing function across the range of acute and chronic wounds

1.5. The required dressing-wound/skin interface conditions during use and removal of dressings

1.6. Bio-physiological environments where dressings must function: Impact on dressing performances

1.7. Identified gaps in evaluation and testing of dressing performances with respect to clinical needs

1.8. Summary and conclusions

Part 1b: Science and engineering of treatment dressings

2. Physical and chemical characteristics of common dressing materials

2.1. Roles of the physical & chemical properties of dressing materials in shaping the fluid management

2.2. Material density and porosity and relevance to mechanical function

2.2.1. Pore and strut shapes, sizes and variability: Relevance to buckling and stiffness of foams

2.2.2. Interconnectivity of pores and tortuosity of the connecting paths: Relevance to fluid flow

2.3. Surface affinity to aqueous solutions (hydrophilicity) and the use of surfactants

2.4. Permeability

2.4.1. Air and gas exchange (vapor-permeability)

2.4.2. Permeability to metabolites, proteins and salts

2.4.3. Hydrophobic (waterproof) features of the external dressing surface

3. Material characteristics and dressing constructs and composites

3.1. Major foam materials currently used in the dressing industry

3.2. Composite foams and foam-gelling fibre dressing structures

3.3. Requirements for chemical and biological stability of dressing materials and constructs

4. Biocompatibility, biological & physiological impact of dressing materials and structures

4.1. Non-cytotoxicity in vitro requirements

4.2. Non-allergenicity/sensitized/irritant materials to patients/healthcare workers: Requirements & standards

4.3. Antimicrobial/antifungal/antiviral materials & treatments in passive, non-drug-eluting dressings

4.3.1. Common embedded antimicrobial and anti-biofilm agents

4.3.2. Sterilizability and sterility maintenance requirements and potential influence on materials

4.3.2.1. Steam

4.3.2.2. Chemical sterilization

4.3.2.3. Radiation

4.3.2.4. Relevant standards and regulatory requirements

4.3.3. Compatibility with commonly used debridement agents and disinfectants

4.3.3.1. Chemical enzyme debriders

4.3.3.2. Chlorhexidine gluconate debriders

4.3.3.3. Povidone-iodine (iodopovidone)

4.3.3.4. Hypochlorous acid

4.4. Biomechanical compatibility aspects: Biological indications of skin damage/stripping

4.5. The epibole concept of rolled wound edges: Relevance to dressing interactions with peri-wound skin & dressing traumas

5. Fluid-structure characteristics and interactions

5.1. Exudate absorption capacity and rate

5.2. Continuity of exudate fluid transfer between the dressing components

5.3. Exudate retention capacity

5.4. Sorptivity

5.5. Moisture vapor transmission rate

5.6. Free swelling and dilatation

5.7. Synergy of different fluid-structure characteristics for optimal fluid management performances

6. Mechanical and contact characteristics

6.1. Stiffness and strength and empirical relationship to density and porosity

6.2. Mechanical protection to the wound-bed

6.2.1. Shear strength

6.2.2. Bending stiffness

6.2.3. Quality of seal to prevent exudate leakage

6.3. Non-adherence of the dressing to the wound-bed and fluid-structure

6.4. Adhesion strength of the dressing borders to peri-wound skin

6.5. Coefficient of friction of the external dressing surface

6.6. Shape conformability of dressings to the wound cavity and to the body surface contours

6.7. Tensile strength, elongation and relevant failure criteria

6.8. Wear-and-tear and the relevance of material fatigue and aging under repeated loading

7. Thermal characteristics

7.1. Specific heat capacity and heat storage capacity

7.2. Thermal conductivity and the importance of adequate insulation

7.3. Thermal absorptivity (warmth-to-touch)

7.4. Thermal diffusivity and effusivity

7.5. Thermal expansion

8. Biological and physiological impacts of dressing performances

8.1. Supporting the wound area and volume reduction, re-epithelialization and collagen deposition

8.2. Managing inflammatory cytokines through dressings

8.3. Managing inflammatory proteases by means of dressings

8.4. The impact of dressings on inflammatory cell infiltration into the wound

8.5. The influence of dressings on angiogenesis and capillary density within & around the wound-bed

8.6. Bacterial trapping and infection reduction measures applied in dressings

8.6.1. Physical bacterial traps

8.6.2. Chemical bacterial traps

8.6.3. Electroceutical dressings

8.7. Physiological measures of dressing performances in wound healing

8.7.1. Direct physiological measures of healing

8.7.2. Indirect physiological measures of healing

8.8. The role of the wound contact layer as the direct dressing-wound interface

9. Theoretical interrelationships among dressing properties that affect performances

9.1. Empirical density-stiffness and density-strength relationships in foams

9.2. Relationship between exudate flux and the pore size

9.3. Relationships between thermal conductivity, density and absorptivity

9.4. Relationship between the dressing surface material and color and thermal absorptivity

Part 2: Clinical practice and patient experience criteria

10. Ease of clinical use and medical benefits

10.1. Ease of clinical application and removal

10.2. Ability to visually inspect the wound-bed and peri-wound skin under the dressing

10.3. Ability and ease of cutting the dressing to shape

10.4. Desloughing and debridement action features

10.5. Peri-wound skin damage or maceration

10.6. The ability of a dressing to stay in place (no rolling, falling-off etc.)

11. Acceptability to patients and immediate care givers

11.1. Physiological measures of discomfort and pain relevant to the function of dressings

11.2. Comfort (or discomfort) and user experience (i.e. ‘feel and touch’)

11.3. Discomfort or pain during dressing removals/changes

11.4. Odor absorbance

11.5. The effects of aging or age-related factors on patient and care giver experiences

11.6. Dressing color and appearance when new/used and cultural variation in perception

11.7. Usability

12. Cost-effectiveness

13. Potential trade-offs between engineering and clinical dressing requirements and patient experience