Skin damage is a result of multiple causative factors such as an attack on the skin by physical, chemical, enzymatic and microbial factors1. This can present as erythema where skin remains intact. Incontinence dermatitis is a result of further deterioration where the skin integrity is lost.
pH of the skin
The skin has an acid mantle of pH 4-6.8. It has a mean pH of 5.5 making it slightly acidic in nature, which is part of its barrier function. The barrier function is affected by the presence of urine and faeces. The skin therefore becomes more alkaline which further increasing the risk of bacterial colonisation2.
Excessive hydration of the skin
Excessive moisture comes from several sources including urine, perspiration and liquid stools. The effect of exposure of the skin to moisture results in maceration and an increase in skin permeability. Skin that is excessively hydrated is more vulnerable to damage by frictional forces. This in turn increases the patient’s risk of pressure ulcer development3.
Excessive hydration along with the increase in pH found with exposure to urine and faeces impairs the barrier function permitting faecal enzymes to attack the skin. The greater the frequency and volume of the incontinence, the greater the risk of skin damage4.
Microbial effects
When urine and faeces mix the bacteria present convert the urea in the urine to ammonia resulting in an increase in the pH of the skin. This destroys the acid mantle allowing irritants to more easily penetrate the skin causing inflammation5. Some microbes are part of the normal skin flora. However, when the barrier function of the skin has been impaired, the skin becomes more susceptible to infection. This includes an increased risk from the normal skin flora.
Occlusion of the skin
Many studies have been carried out on different types of continence pads. They concluded that pads containing super-absorbent materials reduce the wetness of the skin, maintaining the pH as near normal as possible. These super absorbent materials separate the urine from the faeces thereby minimising the risk of faecal enzymatic activity which causes irritation of the skin6.
The use of plastics such as pants, sheets and furniture protectors cause occlusion of the skin as they allow the skin to become wet and cause sweating and excessive hydration. Breathable backed products will reduce this risk.