Skin reactions to wound dressings

Patients with leg ulcers, in particular venous ulcer, exhibit a high incidence of skin reactions to topically applied agents, such as wound dressings and emollients. 

Many of these reactions are sensitisation or ACD. The impact of such reactions includes delayed healing and a consequent increase in treatment costs, as well as reduced quality of life. 

Preventing such reactions should be of concern when selecting a treatment. It is important to be aware of the potential for ACD, and to identify and avoid the use of those dressings and other topical agents known to provoke such reactions.  

Aetiology

The skin surrounding chronic wounds is generally subject to varying degrees of traumatic insult, such as the application and removal of wound dressings/tapes or cleansing procedures. 

This makes the care of peri-wound skin challenging. In patients with venous leg ulcers, changes in the local circulation, in conjunction with venous hypertension, can lead to the development of conditions such as lipodermatosclerosis, atrophie blanche, hyperpigmentation, dryness and scaling. 

Patients with leg ulcers are particularly liable to develop ACD, owing to frequent contact with a variety of topical chemicals, for example, topical steroids/antibiotics, emulsifiers and adhesives applied over a prolonged period of time. 

In addition, it has been postulated that the immune system may be activated early in venous disease by interleukin-1 and -6. The role of IL-1 in Langerhans cell antigen presentation also has an important function in ACD in venous leg ulcer. 

Venous eczema compromises the barrier function of the skin and permits absorption of allergens, resulting in acute sensitisation. Studies have shown that 50-81% of patients with leg ulcers tested for ACD have venous eczema. 

ACD occurs in 1.4-5.4% of the general population and up to 30% of chronic wound patients.¹ This is supported by patch test data showing that 63% and 52% of patients with leg ulcers had reactions to one or multiple allergens, respectively.²The incidence of skin sensitisation in Asian patients with venous leg ulcers showed ACD to be 61.4%.³  

A variety of medical products have been implicated, including latex, nickel, lanolin, emulsifying agents, balsam of Peru and fragrances. The antimicriobial compounds used in wound preparations and dressings can also cause sensitisation reactions, for example, neomycin sulfate, chloramphenicol, bacitracin and cetrimide cream. 

Commonly used antiseptics, such as silver nitrate, silver sulfadiazine, iodine and triclosan, all have sensitising potential. In addition, reactions to wound dressings or their components (for example, adhesives) are common.^4-7 

Cases

Contact urticaria syndrome, a type 1 immediate hypersensitivity reaction (in this case to carboxymethylcellulose in a dressing) has been reported,^8,9 as well as ACD from a hydrogel dressing.¹⁰ 

In one case, a patient with recurrent leg ulcers developed severe eczematous lesions of the skin surrounding an ulcer after the use of a protease-modulating matrix; the sensitising agent was regenerated oxidised cellulose.¹¹

When patch tested, patients reacting to hydrocolloid dressings displayed positive to colophony and to DuoDERM E or DuoDERM CGF. It was concluded that pentaerythritol ester of hydrogenated rosin (used as a tackifying agent) retained the sensitising potential of colophony.¹² 

In a study looking at frequency of contact sensitivities in patients with chronic wounds, 55.5% exhibited contact sensitisation to at least one substance.¹³ 

The most frequent reactions were to PVP-iodine (20%), balsam of Peru (15.6%), fragrance mix (11.1%), colophony (8.8%) and potassium dichromate (6.7%). 

Sensitisation to the Varihesive hydrocolloid of the dressings (also known as DuoDERM and Granuflex 11.1%), Iruxol N (6.7%) and Comfeel hydrocolloid (2.2%) was identified. 

Patients with recalcitrant ulcers showed a higher number of epicutaneous sensitisations to wound dressings than those with ulcers of shorter duration. It is also noteworthy that hydrocolloid dressings and dressings with acrylate adhesive caused severe allergic reactions not seen with soft silicone dressings. 

Diagnosis

The clinical presentation of ACD in conjunction with venous leg ulceration is often confusing. The venous disease often presents with fibrotic changes in the skin, such as lipodermatosclerosis. Poorly controlled exudate frequently leads to excoriation of the skin around the ulcer. Infections, such as erysipelas and especially cellulitis, must be excluded. 

Figures 1-3 illustrate typical ACD reactions. The cutaneous eruption shows erythema, swelling, papules and vesicles in the affected area. Lesions can spread well beyond the area exposed to the allergen. 

Figure 1: Reaction to antibacterial dressing, showing vesicles (Image: Professor RIchard White)

Figure 2: Skin stripping after reaction to dressing adhesive (Image: Professor Richard White)

Figure 3: Marked erythema and vesiculation rules out reaction to exudate. Ulcer shows slough and Pseudomonas infection (Image: Professor Richard White)

Patch testing is the gold standard method for the diagnosis of ACD¹⁴ and has generally been used to identify components of wound care treatment (for example, emollients, dressings) that might have allergens responsible for skin sensitisation reactions. 

A commercially available ‘leg ulcer series’ of known allergens is available for this investigation. It has been suggested that testing high-risk patients should be a prerequisite for choosing appropriate dressings that will not cause sensitisation reactions. Alternatively, steering away from choosing dressings and treatments that have already been shown to be potential sensitisers (such as hydrocolloid dressings) would appear to be a more logical approach.

Treatment

Standard treatment of ACD is simply avoidance or removal of the allergen. Appropriate emollients and soap substitutes may then be used to aid in repairing the skin barrier. Oral antihistamines are useful for the treatment of pruritus. 

Moderate ACD responds to topical corticosteroids used in the lowest concentration and potency that produces a beneficial effect. Severe ACD may require treatment with systemic corticosteroids or other immunosuppressive agents, although evidence supporting their use is limited.

The continuing high prevalence of sensitisation to topical agents in leg ulcer patients suggests that currently, not enough is being done to avoid the problem. 

• Professor Richard White is professor of tissue viability, Institute for Health, University of Worcester

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References

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11. Wounds International. Using Promogran/Promogran Prisma on wounds with elevated protease activity: case studies. 
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