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An Evaluation of an Adhesive Hydrocellular Foam Dressing and a Self-Adherent Soft Silicone Foam Dressing in a Nursing Home Setting
Despite the fact that chronic wound management presents serious medical and economic problems, most countries lack standard treatment guidelines. A chronic wound has been defined as, "one where there is tissue deficit as the result of longstanding injury or insult or frequent recurrence."1 The most common chronic wounds are venous leg ulcers, pressure ulcers, and ulcers of the feet and lower legs associated with diabetes.2
Pressure ulcers represent a significant problem in acute care facilities. In United States' hospitals, approximately 1.6 million ulcers develop each year at a cost to the healthcare system of $2.2 to $3.6 billion (at 1997 prices).3 The annual incidence of hospital-acquired pressure ulcers ranges between 4% and 13% depending on the age and condition of the patient.4,5 The incidence of foot ulceration in people with diabetes is approximately 2.5%.6 Given the observed increase in the number of people with diabetes, the number of individuals with foot problems is also expected to rise.7
Foot ulcers have important implications for patient quality of life and present a serious cost burden to the healthcare system. Ramsey8 estimated the additional costs associated with newly diagnosed foot ulcers in patients with diabetes at a large staff-model HMO. The average treatment cost per patient for the 12 months following diagnosis was $10,742 higher than annual pre-diagnosis costs for the same patients (at 1995 prices).8 Harrington9 found that in 1995, Medicare expenditures for patients with diabetes and a lower extremity ulcer were on average $10,083 higher than for Medicare patients in general. In patients with open ulcers, 55% had their ulceration for at least 1 year, and in 40% of patients, multiple lesions are present.10 Non-adherence with treatment is a major problem and recurrent ulceration is a factor for 55% of patients with an open ulcer. With the number of older adults increasing in most industrialized countries, by the year 2020, the proportion of people 65 years of age or older is expected to rise from the current 12% to 16% to 20% of the population.11 This rise in the number of elderly patients will most likely be accompanied by an increase in the occurrence of chronic wounds.
Moist chronic wounds are an ideal environment for bacterial growth - a variety of micro-organisms can be cultured from these lesions. Studies have shown that more than 80% of chronic leg ulcers can be contaminated with bacteria,12,13 the most common isolates being Staphylococcus aureus and Pseudomonas aeruginosa.14,15 Pressure ulcers may have a varied bacteriological flora, with anaerobic organisms cultured more frequently than anaerobes; S. aureus, Streptococcus spp., Proteus spp, Escherichia coli, Pseudomonas, Klebsiella, and Citrobacter species are the most common isolates.13,16,17 P. aeruginosa and anaerobes may be cultured from diabetic foot ulcers; Enterobacteriaceae and anaerobes are often present in the discharge from chronic pilonidal sinuses.
The relationship between bacterial colonization and wound closure remains unclear.12,14 Although higher bacterial counts may be associated with failure to heal,12,15 some sources suggest that the presence of bacteria is unimportant.14 However, other findings indicate that the presence of four or more bacterial groups may be associated with delayed closure.18 Typically Gram-positive bacteria (including S. aureus or S. pyogenes) cause infections, requiring systemic antimicrobials such as amino-penicillins (eg, ampicillin) or cephalosporins; thus, adding to the discomfort and cost of wound management.
A variety of dressings, mostly intended to provide an optimal environment to allow the natural healing process to occur, are available. Dressings should not only protect the wound from microbial invasion, but also from abrasions or external mechanical forces that may further hinder the healing process. Moreover, a dressing should not cause skin damage upon removal.
Dressings utilizing soft silicone adhesive technology (Safetac®, Mölnlycke Health Care, Newtown, Pa.) are purported to cause less trauma and pain on removal than other types of dressing. This claim is based on models using human volunteers and pre-stained skin. In a recently published study,19 peel force was measured and related to the amount of stratum corneum removed and was directly related to "damage" to the skin surface. However, the results of this study, conducted with volunteers, who applied the dressing to healthy forearm skin, may not be representative of the potential removal of periwound stratum corneum in the clinical setting. Removal of stratum corneum may or may not cause skin damage. The stratum corneum is the outer layer of the epidermis - it undergoes keratinization, during which the cells fill with keratin, die, and wear off. It is possible, therefore, that the model19 is measuring a natural process and may not be a reliable measure of selecting adhesive dressings that minimize trauma to surrounding skin. An alternative method to assess adhesive dressing performance could be examining clinical evidence of skin stripping where skin stripping is defined, not as removal of the stratum corneum, but as the cause of minor small abrasions that, with repeated trauma, may cause skin irritation, eczema, itching, and potential bacterial invasion and infection.20-22 A retrospective descriptive study was conducted to assess the performance of two wound dressings in clinical practice.
Materials and Methods
Background and objectives. In 30 Wound Clinic of America nursing homes in the state of Florida, a purchasing decision had been made to switch from using a hydrocellular dressing (Allevyn Adhesive dressing, Smith + Nephew, Largo, Fla.) to a soft-silicone dressing (Mepilex® Border, Mölnlycke Health Care, Newtown, Pa.). To ascertain the effects of this change on wound outcomes, data collected during the provision of regular care by Wound Clinic of America clinicians was analyzed retrospectively. Specifically, the occurrence of periwound skin stripping (defined as periwound skin blistering) and wound closure and infection rates were evaluated. Data were retrieved from a database covering a 5-year period (May 27, 1997 to June 18, 2002). All information was collected as part of normal care procedures and entered in a "real time" database. All patients in the database who had a pressure ulcer, venous ulcer, diabetic ulcer, or traumatic wound that was treated with either the hydrocellular or soft-silicone dressing or both dressings on at least one occasion were included.
The study was audited by a clinician in the US; patient records were checked before entry into the database. The number of patients treated with the hydrocellular dressing was larger than those treated with the soft silicone dressing because the latter was only commercially available after June 2001.
Because all nursing homes in the study are in the state of Florida, they are regulated by state and US federal mandates and meet a minimum set of standards as determined and regulated by the US and Florida government agencies. The number of ulcers per patient was similar for all nursing homes in this study. The data analysis set included patients who had a wound that was treated on at least one occasion with the hydrocellular dressing or soft silicone dressing. Specific assessments included: demographic information, baseline wound variables, wound closure, evidence of skin stripping, and evidence of wound infection. Wound closure was defined as wound healing and consisted of a yes/no variable in the database. Wound infection was defined as any wound treated with an antibiotic solution comprising 80 mg gentamycin, 600 mg clindamycin, and two ampules of polymixin (GCP) plus 250 cc sterile normal saline solution at any assessment. If infection was suspected, systemic antibiotics also were administered.
Assessments were made consistently by one nurse in conjunction with the clinician and recorded in real time at the patient's bedside. Patient and wound baseline data were summarized for all patients and by dressing type. Baseline values were obtained from the first recorded assessment for a particular wound in the database. Because some wounds were treated with both the hydrocellular and soft silicone dressings, a new dressing type category ("both dressings") was created for this study.
Skin stripping and other wound characteristics, observed and recorded at each follow-up (post baseline) assessment, were summarized for all patients by dressing type.
The clinical need for antimicrobial or GCP therapy was recorded and adverse events were monitored. Qualitative measurements of patient comfort and dressing regimen acceptability was obtained by patient interview and recorded at each dressing change.
Data analysis. Data were transferred to SAS/STAT version 8 (SAS Institute, Inc., Cary, NC) and descriptive statistics were used to analyze the information.
Results
Patient demographics. The wounds of 1,891 patients were managed with a hydrocellular or soft silicone dressing on at least one occasion. Of these, 1,643 (87%) received the hydrocellular dressing, 162 (9%) received the soft silicone dressing, and 86 (4%) patients were treated with both dressings (see Table 1).
The mean patient age was 82.5 years (range 29 years to 106 years). Patients who were treated with the hydrocellular dressing only had a mean age of 82.5 years (range 29 to 106 years). Patients treated with soft silicone dressing only had a mean age of 83 years (range 58 to 102 years). Of the 1,891 participants, 1,036 (55%) had more than one wound and 34 (2%) had 11 or more wounds.
Baseline wound characteristics. Of the 4,200 wounds included in this study, 3,795 (90%) were treated with the hydrocellular dressing, 352 (8%) were treated with the silicone dressing, and 53 (1%) wounds received both dressings during their course of treatment. Wounds treated with hydrocellular dressing were slightly larger (mean area 7.53 cm2, SD 13.66) and deeper (mean 0.46 cm, SD 0.7), than wounds treated with soft silicone dressing (mean area 5.50 cm2, SD 8.74; mean depth 0.19 cm, SD 0.16) (see Table 2).
Of the 53 wounds treated with both hydrocellular and soft silicone dressing, 50 (94%) changed from hydrocellular to soft silicone dressing during treatment and three (6%) changed from soft silicone to hydrocellular dressing during treatment. The majority of wounds were pressure ulcers (3,969 of 4,200 [greater than94%]), 160 (4%) were traumatic ulcers, 10 (less than1%) were diabetic ulcers, six (less than1%) were inflammatory wounds, 20 (less than1%) were ischemic ulcers, 18 (less than1%) were postoperative wounds, and 17 (less than1%) were venous stasis ulcers (see Table 2).
At the first recorded assessment (baseline), 2,807 of 4,196 wounds (67%) had normal periwound skin; 2,636 out of 3,792 (70%) were wounds treated with hydrocellular dressing, and 152 out of 351 (43%) were treated with soft silicone dressing. Of the 4,196 wounds, 15 (less than 1%) had evidence of skin stripping (periwound blistering) at the baseline assessment, corresponding to 11 out of 3,792 (less than1%) of the wounds treated with the hydrocellular dressing and four out of 351 (1%) treated with the soft silicone dressing (see Table 2 and Table 3).
Wound healing. The closure rates achieved using the two dressings were similar: 1,996 of 3,795 (53%) wounds treated with the hydrocellular and 175 of 352 (50%) wounds treated with the soft silicone dressing healed during an average treatment time of 71.3 days (range: 5 to 1,386 days) (see Table 4).
Evidence of skin stripping. Little evidence of skin stripping was observed or measured, with 17 of 2,773 (less than 1%) wounds noted to have evidence of skin stripping at any follow-up assessment. This corresponded to 13 of 2,546 (less than 1%) wounds treated with the hydrocellular and four of 227 (2%) wounds treated with soft silicone dressing. Of the 17 wounds that experienced skin stripping, 16 were pressure ulcers (12 treated with hydrocellular dressing and four treated with soft silicone dressing) and one was a venous ulcer (treated with hydrocellular dressing).
Sixteen (16) of the 1,380 patients (1%) experienced skin stripping on at least one assessment, corresponding to 13 of the 1,266 (1%) patients treated with hydrocellular dressing and three of the 114 patients (3%) treated with soft silicone dressing. Overall, skin stripping was observed at 40 of the 13,860 (less than1%) follow-up assessments, corresponding to 29 of the 12,724 (less than1%) assessments of patients treated with hydrocellular dressing and 11 of the 1,136 (less than1%) assessments of patients treated with the soft silicone dressing.
Wound infection. Ninety-nine out of 2,881 wounds (3%) experienced an infection, corresponding to 76 out of 2,616 (3%) treated with the hydrocellular dressing and 23 out of 265 (9%) treated with the soft silicone dressing. No differences were observed between the different nursing homes in terms of the incidence of infection or any other variable (see Table 6).
Product evaluation. Nursing evaluation of the two products over the study period recorded that the soft silicone dressing often failed to adhere to the wound area following application or to remain in place between dressing changes, requiring the use of additional adhesive tape to remain in situ. In contrast, the hydrocellular dressing was reported as easy to apply, and remained in place between dressing changes.
Discussion
This large cohort assessment of 4,200 patients with various types of wounds provides a real-world outcome evaluation of the care provided by trained professionals using two different types of dressings. All cases that qualified for evaluation were included in the assessment, and the two cohorts were comparable in demographics and wound location, although more traumatic ulcers were noted in the hydrocellular dressing group and more wounds were managed using the hydrocellular dressing because it has been available for a longer period of time. Wounds in the hydrocellular dressing group tended to be longer, deeper, and larger overall. The wounds in the two groups appeared similar in initial presentation in terms of erythema, blistering, and other parameters. The results of this evaluation suggest that using the "new" soft silicone dressing offers no advantage in terms of skin stripping. Both dressings could be considered atraumatic as defined by Thomas,23 who proposed the term atraumatic dressing to define products which, on removal, do not cause trauma either to newly formed tissue or the periwound skin.
Assessments were made by experienced nurses in accordance with guidelines for the treatment of pressure ulcers (National Pressure Ulcer Advisory Panel: https://www.npuap.org), and independent nurse evaluations of the two dressings were recorded over the study period. The benefit of these regular assessments is that they provide consistent and reproducible evaluations of the same patient over a defined period of time using the same criteria for observing changes in wound status. Independent nurse evaluations of the dressings highlighted the failure of the soft silicone dressing to either initially adhere to the wound area or to remain in contact for more than a few days, frequently requiring extra adhesive tape to ensure long-term adhesion (see Figure 1). Of the 2,546 wounds treated with the hydrocellular dressing and the 227 wounds treated with soft silicone dressing, 13 (less than 1%) and four (2%), respectively, experienced skin stripping at any follow-up assessment. Overall, 17 out of 2,773 (less than1%) wounds experienced skin stripping. These findings are supported in recently published systematic reviews.20-22 Skin stripping occurred in 40 out of 13,860 (less than1%) follow-up assessments - 29 out of 12,724 (less than1%) in wounds treated with treated with hydrocellular dressing and 11 out of 1,136 (less than1%) treated with soft silicone dressing.
Pain and trauma associated with dressing removal are a major concern to patients and healthcare professionals. The results of this retrospective analysis suggest that both hydrocellular and soft silicone dressings cause minimal trauma.
If wounds become dry and exposed to the environment because dressings fail to remain in place, they are more likely to become infected.24,25 Ninety-nine out of 2,881 wounds experienced an infection at any assessment. A higher infection rate was observed with use of the soft silicone dressing (23 out of 265, 9%) compared to the hydrocellular dressing (76 out of 2,616 or 3%). Infections of ulcers requiring antimicrobial therapy can negate any savings anticipated when using less expensive dressings. However, bacteriological evaluations were not conducted in this study and additional clinical trials are needed to compare the incidence of wound infection between different dressing regimens. The results of this study are comparable with recent systematic reviews of wound dressings20-22 and support the hypothesis that, in clinical practice, differences in dressing tolerability are limited. The limitations of retrospective analysis are well known and documented. However, the validity of the findings reported here is strengthened by the number of patients and observations included in this retrospective analysis, adding much needed outcomes data to the area of wound care.
Conclusion
Wound dressing selection is based on many factors, including cost, convenience, and outcomes such as skin stripping and wound closure. The results of this study suggest that both dressings may achieve satisfactory outcomes but adhesion can be problematic with the soft silicone dressing evaluated. This, in turn, may increase the risk of infection and may be a significant deterrent to staff to confidently routinely apply this type of dressing. The clinical and economic ramifications of these observations require further study.
Acknowledgments
The authors would like to acknowledge Smith + Nephew for their help with the statistical analysis of the database, and Magus Strategic Communications Ltd. (UK) for their editorial input.
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