A Comparison of the Wear Time of Dressings with Silicone Adhesives
Sarah Jackson, Sarah Lay, Christian Stephenson
Crawford Healthcare, King Edward Court, King Edward Road, Knutsford, Cheshire, UK
Dressings that utilise soft silicone adhesives are widely-used and common place in the treatment of chronic wounds. Soft silicone adhesives provide gentle, pain-free removal, preventing trauma to the skin, but can be difficult to remain adhered to awkward areas. The ability of a dressing to adhere to a patient is dependent on a number of factors. These include the resistance of the dressing to edge-roll on contact with clothing and bedding, the flexibility of the dressing, and the strength of the silicone adhesive. Also important is the ability of a dressing to retain fluid, as if the peri-wound area is wet or macerated, a hydrophobic silicone adhesive will not stick.
To compare foam dressings with a silicone adhesive to quantify design features that aid dressing retention/fixation.
The resistance of dressings (12.5x12.5cm, or nearest available size) to edge-roll was tested using a novel rolling simulator (see figure 1). Lateral forces were applied across the dressing surface by the presence of a weighted cotton bed sheet in order to simulate forces experienced by the dressing when adhered to a patient in a bed. The dressings were tested on the simulator for one minute at a constant rate of rotation, after which the percentage lift of the dressings was measured. A one minute test was selected to provide a controlled comparison of the dressings. Four replicates were tested of each silicone foam dressings.
A bending length test was used to measure the flexibility of the sacral shape of each dressing. In this test, the length that a dressing freely bends over an edge is measured in order to quantify the flex of the material. The larger the value for bending length, the more flexible a material. Three replicates were conducted of four different silicone foam dressings.
Fluid retention was determined by saturating a 12.5x12.5cm (or nearest available size) dressing with Solution A, heated to a temperature of 37°C. A uniform weight (5kg) was then applied to the dressing to apply a total compression of 30mmHg in order to quantify the fluid released on dressing compression. Three replicates were conducted of four different silicone foam dressings.
Volunteer Evaluation (VE)
Dressings were assessed for wear time in a healthy volunteer evaluation, in which four volunteers wore six foam dressings (7.5x7.5cm, or nearest available size) on their outer thighs for a 7-day test period. The percentage lift and wear times of each of the dressings was assessed.
Results & Discussion
The percentage lift following one minute on the rolling simulator are shown in table 1.
The simulator demonstrated a scenario where a dressing is repeatedly subjected to rolling contact with a bed sheet. This type of contact would be expected if a patient is bed-bound or largely immobile. The consistent speed and force enabled a controlled environment to directly compare each dressing.
When dressings experience edge-roll from clothing or bedding, they could easily go on to become completely detached from the patient-which could lead to at-risk areas no longer being protected, or costly use of multiple dressings. It is therefore important to understand the impact of lateral forces from movement in bedding.
A range of edge-roll results from 0% to 30% were seen in the dressings after one minute of use simulation, showing that some dressings lift from the edges more easily than others.
Bending length results can be used to further understand factors leading to dressing adherence. The results for this test are shown in graph 1.
Dressings that don’t flex or bend with the body have an increased risk of becoming easily detached. Again, a range in results were seen in the bending length test indicating a variation in the flexibility of silicone foam dressings. The results for flexibility trend with those seen on the rolling simulator, with the least flexible dressing (Allevyn Life) showing the most lift.
Fluid retention results as a percentage of total absorptive capacity, are shown in table 2.
Dressings that don’t retain fluid within their structure are likely to leak on compression. If the peri-wound area is wet, a silicone dressing will not adhere to the skin, as silicone adhesives are hydrophobic. Dressings with a lower fluid retention may have adhesion problems as they release more exudate on compression.
In the VE, a range of dressing wear time results were found. KerraFoam Gentle Border and Mepilex Border had similar average wear times of 6 and 6.25 days. Allevyn Gentle Border and Biatain Silicone had slightly lower average wear times of 5.5 and 4.75 days. Tielle Silicone Border performed noticeably worse than the other dressings, with an average wear time of only 1.75 days (see graph 2).
The data clearly shows how the differences in the characteristics of silicone dressings can have a vast impact of the ability of the dressings to remain adhered. Although all of the dressings tested were foam dressings, with silicone wound contact adhesives, a variation in in-vitro performance was seen, and in the VE some dressings were able to be retained up to 6 days, and others only 1.75 days.
The results indicated that not all silicone foam dressings share design features to aid fixation and adhesion to a patient. The rolling simulator showed large differences between a dressing’s ability to remain adhered when subjected to lateral forces against bedding.
Flexibility (bending length) tests showed trending between flexibility and fixation.
The volunteer trial provided similar results to the in-vitro testing, showing the benefits of in-vitro studies in dressing selection.