Hydrofibre technology is a promising type of moist dressing used in split-thickness skin graft (STSG) donor sites.1,2,3 Aquacel and Aquacel Foam (both ConvaTec Ltd., UK) are two commonly used moist dressings in clinical practice.
STSG is a widely used reconstructive technique for various indications, including burn wounds, traumatic wounds, infection and hard-to-heal ulcers. This procedure involves the harvesting of a sheet of skin comprising the epidermis and varying thicknesses of dermis which, as a consequence, also involves the creation of a superficial donor site wound. Due to the nerve exposure in STSG donor sites, pain from post-harvest wound management dressing change is inevitable.1 Thus, determining the optimal dressing for STSG donor sites is critical, as high levels of pain at donor sites can result in a prolonged hospital stay, increased pain medication use, decreased mobility, and negatively influence the patient's quality of life (QoL).4,5
Based on findings in the literature, moist dressings have demonstrated superiority in wound management of STSG donor sites.4,6,7 A recent systematic review on STSG donor site dressings involving 41 clinical trials comparing 44 dressings revealed that moist dressings (for example, Aquacel, Kaltostat (both ConvaTec Ltd., UK), Mepitel (Mölnlycke, Sweden), Tegaderm (3M, US)) result in lower pain and faster wound healing compared with non-moist dressings (for example, Xeroform (Cardinal Health, US), paraffin-impregnated gauze).4 However, an ideal dressing for management of STSG has yet to be identified because of the high heterogeneity among studies and types of dressings. The increasing number of novel dressings necessitates further well-designed comparison studies, along with quantitative metrics of outcomes, to inform clinical practice. This paper describes a comparison of Aquacel (A) and Aquacel Foam (AF) in terms of pain, wound healing, infection and cost.
Aquacel Hydrofiber is a dressing composed of carboxymethylcellulose hydrocolloid fibre material. This material absorbs wound exudate to form a cohesive gel, creating a moist environment to promote tissue repair and wound healing.8,9 The technology was developed in 1996 and has since shown promising results in STSG donor site wound management.10 It has demonstrated superiority in supporting re-epithelialisation and ease of application against other moist and non-moist dressings (i.e., hydrocolloid, polyurethane film, cellulose-based, tulle gras).1
An adhesive dressing incorporating hydrofibre technology, namely AF, was later developed. It comprises a protective top layer, an upper polyurethane absorbent foam pad, and an integral hydrofibre wound contact layer with a silicone adhesive border. A secondary dressing is not required for AF, and its high level of adhesiveness is predictive of longer dressing wear time. Furthermore, the outer layer of AF is waterproofed, and serves as a viral and bacterial barrier.8,11 Due to the potential advantageous properties of AF, it may be a superior dressing for STSG wounds than A in reducing pain, infection and cost.
Hydrofibre technology has demonstrated favourable outcomes (i.e., healing rate, pain, cost per unit, ease of use) in STSG donor site clinical trials in comparison to other dressing types.1,2,3 Clinical studies in other surgical wounds (i.e., joint surgery) have demonstrated that Aquacel dressings result in fewer wound complications and are less painful than traditional dressings.12,13 Furthermore, one microscopic examination study found that the unique gelling properties of A appeared to provide a more optimal environment to immobilise bacteria compared with other moist dressings.14
AF, on the other hand, is less well studied, even though some researchers have suggested that it may have greater benefit compared with other hydrofibre dressings, as it contains secondary dressings within itself.15,16 In clinical practice, dressing selection is often based on physicians' personal preferences without evidenced-based consensus from clinical studies.4 Evidence on differentiating the effectiveness among hydrofibre products is warranted. The study presented in this paper aimed to compare the effectiveness of dressing A and dressing AF, two commonly used hydrofibre products, in managing STSG donor sites by evaluating pain, intravenous analgesics use, time to wound healing, infection rate and costs associated with dressing change. We hypothesised that the AF dressing would be superior in improving clinical outcomes in STSG patients because of its advantageous bioproperties. The findings could better inform clinical guidelines on STSG donor site dressing selection and improve patient-centred wound care.
Method
This was a quasi-experimental study. It was approved by the institute review board of Taipei Veterans General Hospital (VGHTPE-2016-01-008BC). The sampling period was from September 2015 to March 2016. Eligible patients in the study hospital were approached before the reconstruction surgery, and written informed consent was collected from enrolled patients.
Patient inclusion criteria:
- Adults ≥18 years of age
- Able to communicate in Mandarin or Taiwanese
- Planned to undergo STSG harvesting for reconstruction
- Donor sites located in head or thigh, not reharvested, and ranging from 10–600cm2 in area.
Patient exclusion criteria:
- Cognitively impaired
- Had prior experience of using either dressing A or dressing AF for wound care
- Known hypersensitivity to the wound dressings used in the study
- Altered sensation in the planned donor site
- Known history of non-adherence with medical treatment.
Intervention
In the reconstruction surgery, all of the grafts were harvested by the surgeon in a standardised manner by using a powered dermatome (Acculan Dermatome, Aesculap Power Systems, Aesculap Inc., US) adjusted to 0.25–0.5mm thickness. Haemostasis was achieved by compressing epinephrine-soaked gauzes (1:200000) for 15 minutes, followed by coverage with either dressing A or dressing AF. The use of dressing A or dressing AF was determined by the preference of the surgeon with no other discrepancies in wound management.
In the A dressing group, gauze pads and elastic bandages were used as the external compression dressings, which were changed every 48 hours; whereas dressing A (primary dressing) was only changed when leakage, or large amounts of secretion or infection occurred. In the AF dressing group, external compression dressings were only used if deemed necessary (i.e., excessive secretion), and were only changed if necessary (i.e., leakage, excessive secretion, infection). The AF dressing was also only changed if necessary. For both groups, in the case of suspected wound infection, the primary dressing was removed immediately and intensive wound management (for example, culture collection, twice daily dressing change, intravenous antibiotics) was implemented.
Measurement
After surgery, daily wound assessments and dressing changes were conducted and recorded by two trained research nurses. Pain on dressing removal, dressing materials used, use of intravenous analgesics, signs and symptoms of wound infection, incidence of exudate leakage and percentage healed were documented by the two nurses for each dressing change in a standardised form.
Clinical and demographic data (i.e., age, sex, comorbidities, characteristics of STSG donor site) were retrieved through the patients' electronic medical records. The cost of dressing materials was retrieved through the hospital billing system after patient discharge. In particular, the two dressings were compared in terms of pain, time to wound healing, infection rate, and cost of dressings per cm2.
Pain
Local pain immediately after each dressing removal was scored using a Visual Analogue Scale (VAS), from 0 (no pain) through to 10 (worst pain) by patients and recorded by the research nurse.17 Intravenous analgesics were administered during dressing change as needed and documented.
Time to wound healing
Time to wound healing was defined as days to ‘90% re-epithelialisation’, which was recorded as the date on which research staff noted ‘90% re-epithelialisation’ during dressing changes.1
Infection
Local signs of infection (i.e., purulent exudate secretion, swelling or redness of the surrounding skin, fever and increasing pain) were documented and a standard protocol was followed in the case of suspected wound infection.18
Cost
The cost of dressing materials per wound area was calculated by dividing the total dressing cost by the postoperative wound surface area (cm2).
Statistical analysis
The Statistical Package for the Social Sciences (SPSS) for Windows (SPSS Inc., US), version 19.0, was used for statistical analysis. Frequency data were presented as percentages and numerical data were expressed as mean±standard deviation (SD) or range. Chi-squared tests and t-tests were performed to assess differences between the A and AF dressing groups in terms of their demographic clinical characteristics. Linear regressions were conducted to examine the differential effects between dressing A and the AF dressing on continuous clinical outcomes (i.e., pain scores, wound-healing time, the cost for dressing change and first dressing change day since operation), whereas logistic regressions were performed to examine the association between dressing materials and categorical clinical outcomes (i.e., exudate leakage and analgesics use). Linear regression adjusted for known factors associated with wound pain (i.e., age, sex, wound area) were performed. Significance was defined as p<0.05.
Results
Of the total number of patients included (n=50), 25 (18 male and seven female) received AF as the primary dressing for their STSG donor sites, and 25 (18 male and seven female) received dressing A. Mean patient age was 49.5 years (range: 17–80 years). The primary diagnosis for the required skin graft included oncologic surgery (n=23, 46%), acute wounds (n=15, 30%) and pressure ulcers (n=12, 24%). Baseline characteristic differences between the two groups were not statistically significant (Table 1). The mean surface area of the donor site was 141.8±143.9cm2 in the A dressing group and 102.6±66.1cm2 in the AF dressing group (p=0.23).
Table 1. Baseline patient characteristics by treatment allocation group
| Patient characteristics | Aquacel (n=25) | Aquacel foam (n=25) | p-value* | ||
|---|---|---|---|---|---|
| n | % | n | % | ||
| Sex | 1.00 | ||||
| Male | 18 | 72 | 18 | 72 | |
| Female | 7 | 28 | 7 | 28 | |
| Age, years, mean±SD | 46.8±15.9 | 52.1±15.3 | 0.24 | ||
| Diabetes | 2 | 8 | 6 | 24 | 0.12 |
| Smoker | 12 | 48 | 8 | 32 | 0.25 |
| Main diagnosis | 0.14 | ||||
| Pressure ulcer | 3 | 12 | 9 | 36 | |
| Acute wound | 9 | 36 | 6 | 24 | |
| Tumour | 13 | 52 | 10 | 40 | |
| Location of donor site | 0.07 | ||||
| Thigh | 22 | 88 | 25 | 100 | |
| Acute wound | 9 | 36 | 6 | 24 | |
| Area of donor site, cm2, mean±SD | 141.8±143.9 | 102.6±66.1 | 0.23 | ||
SD—standard deviation;
* p-values obtained by t-test or Chi-squared testPrimary outcome: pain
Table 2 shows the descriptive clinical data of the two groups. The mean pain scores were lower in the AF dressing group for each of the first three dressing changes, and the difference was most notable for the initial change; the average pain on removal was 4.7 points higher in the A dressing group. Overall, the average pain score on dressing removal was lower when AF dressings were used compared with the A dressing (0.8±0.8 versus 3.1±1.5, respectively). In addition, a lower percentage of patients using the AF dressing received as-needed intravenous analgesics during dressing change compared with patients using dressing A (24% versus 60%, respectively).
Table 2. Perioperative descriptive data by treatment allocation group
| Aquacel (n=25) | Aquacel foam (n=25) | |||
|---|---|---|---|---|
| n | % | n | % | |
| Wound healing time, days, mean±SD | 14.8±3.7 | 16.7±4.2 | ||
| Exudate leakage | 11 | 44 | 2 | 8 |
| Cost of dressing per cm2, NT$, mean±SD | 11.7±19.0 | 6.2±6.6 | ||
| Days since first dressing change, mean±SD | 1.9±0.8 | 4.0±4.8 | ||
| Pain score, mean±SD | 3.15±1.5 | 0.8±0.8 | ||
| Pain at first dressing change (n=25:25), mean±SD | 5.5±2.0 | 0.8±1.1 | ||
| Pain at second dressing change (n=25:23), mean±SD | 4.2±2.2 | 0.8±0.9 | ||
| Pain at third dressing change (n=24:13), mean±SD | 2.8±2.3 | 1.3±1.3 | ||
| Analgesics use | 15 | 60 | 6 | 24 |
SD—standard deviation; NT$—New Taiwan dollar
Regression analysis demonstrated that, compared with dressing A, the AF dressing predicted a lower likelihood of PRN intravenous analgesic use (OR=0.21, 95% CI: 0.06–0.71, p=0.01; Table 3), lower pain scores for each of the first three dressing changes (first dressing change: beta=–4.72, SE=0.46, p<0.001; second dressing change: beta=–3.41, SE=0.49, p<0.001; third dressing change: beta=–1.48, SE=0.69, p=0.04), as well as a lower average pain score (beta=–2.27, SE=0.33, p<0.001; Table 4). The result was unchanged in linear regression adjusted for age, sex, and wound area.
Table 3. Logistic regression examining the influence of Aquacel Foam compared with Aquacel on clinical outcomes
| Odds ratio | 95% Confidence Interval | p-value | |
|---|---|---|---|
| Exudate leakage | 0.11 | (0.02, 057) | 0.01 |
| Analgesics used | 0.21 | (0.06, 0.71) | 0.01 |
Table 4. Linear regression examining the influence of Aquacel Foam compared with Aquacel on clinical outcomes
| β | 95% CI | SE | p-value | |
|---|---|---|---|---|
| Wound healing time | 1.84 | (–0.41, 4.09) | 1.12 | 0.11 |
| Total cost per area | –5.53 | (–13.60, 2.55) | 4.02 | 0.18 |
| First dressing change day since operation | 2.16 | (0.21, 4.11) | 0.97 | 0.03 |
| Mean pain score | –2.27 | (–2.94, –1.60) | 0.33 | <0.001 |
| Pain at first dressing change | –4.72 | (–5.65, –3.79) | 0.46 | <0.001 |
| Pain at second dressing change | –3.41 | (–4.40, –2.43) | 0.49 | <0.001 |
| Pain at third dressing change | –1.48 | (–2.89, –0.08) | 0.69 | 0.04 |
β—beta; CI—confidence interval; SE—standard error
Secondary outcomes: complete wound healing, adverse events and dressing cost
Mean time to complete wound healing was 17 days in the AF dressing group and 15 days in the A dressing group; however, the difference was not statistically significant in linear regression (beta=1.84, p=0.11; Table 4).
No wound infection was observed in either group. No allergic reactions or other adverse events were reported from either group during the study. Exudate leakage occurred in 11 patients from the A dressing group, and two patients from the AF dressing group, with logistic regressions showing that the AF dressing predicted a lower likelihood of exudate leakage (OR=0.11, p=0.01; Table 3).
The average dressing cost per wound area (cm2) was $0.40±0.65 USD in the A dressing group and $0.21±0.22 USD in the AF dressing group. The difference in cost was not statistically significant in the linear regression model (beta=–5.53, p=0.18).
Discussion
Our study is the first clinical study to investigate and compare the effectiveness of dressing A and dressing AF, two commonly used hydrofibre dressings, in STSG donor site wound management. The AF dressing was superior in pain reduction on dressing removal and in reducing incidences of exudate leakage when compared to dressing A; however, no statistically significant differences were found in time to wound healing, infection rate or dressing costs between the two groups.
Donor site pain is one of the most distressing symptoms in skin graft patients and dressing removal often exacerbates the patient's experience of pain.6,19 Careful dressing selection is crucial to avoid the pain and trauma related to dressing change.20 In our study, the AF dressing was more effective in reducing pain during dressing change than dressing A. Pain on dressing removal has not been investigated extensively in hydrofibre; only one other study examining hydrofibre has reported this outcome.21 Lohsiriwat and Chuangsuwanich reported in their clinical study that the average pain score on the removal of Aquacel Ag (AAg) (ConvaTec Ltd., UK) was 3.12 in STSG donor sites, which was similar to the score reported in our A dressing group (3.1).21 AAg is another hydrofibre product, similar to dressing A used in this study but with antimicrobial ionic sliver; therefore, it is not surprising that AAg and dressing A have a similar wound dressing pain score.22 However, this product was not included in our study because the cytotoxicity of ionic silver causes delay to wound healing and it is not used in the study hospital.22
The average pain score in the AF dressing group in our sample was comparatively low (0.8). Low pain level at removal of the AF dressing was also found in a multicentre single-group design product evaluation, where 84% of the patients experienced no pain at dressing removal.23 However, more studies are warranted to compare the effects of the AF dressing with a wider range of different dressing materials. A clinical trial in hip and knee surgery found that the average wound dressing pain score using dressing A was 1.2±1.5, which is lower than the result in our study but still higher than the pain score of the AF dressing group.12 AF has the potential to reduce pain in patients with other surgical wounds, and well-designed studies in other patient populations (for example, hip and knee surgery) are needed to explore the effectiveness of the AF dressing.
Overall, the AF dressing demonstrated a higher performance for managing pain on dressing removal, which can potentially be explained by several factors. First, the multilayer absorbent foam pad in the AF dressing may be more effective in absorbing and retaining fluid than the single-layer A dressing, as evidenced by a higher incidence of exudate leakage in the A dressing group than in the AF dressing group (11 versus two patients, respectively) in this study. Exudate leakage is associated with frequent dressing change and irritation of the periwound area, intensifying pain on dressing removal. Therefore, patients in the A dressing group may report higher pain intensity.24 Second, secondary dressings (i.e., gauze pads and elastic bands) used in combination with dressing A might affect pain levels on removal. The authors of a review study on STSG donor site dressings hypothesised that secondary dressings might cause more pain due to the pull of the exudate-filled secondary dressing on the macerated skin.6 The gauze pad applied to support dressing A might have absorbed excessive wound exudate and subsequently dried out the primary dressing, causing more pain during dressing change. Accordingly, the AF dressing would be the more suitable dressing material for pain reduction in STSG donor sites.
The total dressing cost per wound area was not statistically significant. Per unit, the AF dressing is more expensive than the A dressing; for example, one unit of 15×15cm AF dressing costs $13 USD, while the same size of the A dressing costs $8 USD. However, external compressive dressings were more frequently applied in the A dressing group due to the higher incidence of exudate leakage, resulting in higher overall cost. The AF is used as a single dressing with both traditional primary and secondary dressing functions; thus, the AF dressing could potentially be more economical in terms of cost compared with the A dressing.8
This study also demonstrates the safety of both dressings. No infections or other adverse events were observed in either group. Hydrofibre in both dressings created occlusive environments and effectively prevented external contamination, echoing the low infection rate in another clinical trial that used a hydrofibre dressing.1 The outer layer of the AF dressing serves as a waterproof viral and bacterial barrier, which can potentially be more effective in preventing wound-related infections.8
Limitations
This study has several limitations. First, this study is limited by the small sample size and the non-randomised design may increase the risk of bias. Second, even though pain on dressing removal is an important indicator for pain management in STSG donor site wounds, outcomes such as pain at rest, during movement and on certain postoperative days (for example, postoperative day 2, postoperative day 7) are also worth evaluation; these outcomes were not collected in our study. Third, our study did not measure patient experience with wound management. Patient-reported outcomes, such as wound-related anxiety, dressing satisfaction and impact on daily activities, should be incorporated into future studies. Fourth, we did not measure medium- or long-term outcomes, such as quality of scarring, which might help us to make a more comprehensive conclusion on dressing recommendation. Last, outcome assessors were not blinded in our study, which might introduce assessor bias. The authors recommend future research to include more comprehensive pain assessment and longer-term outcomes, as well as outcomes on patient satisfaction. In addition, outcome assessors should be blinded from group allocation and study design to minimise the risk of bias.
Conclusion
In this study, the AF dressing demonstrated superior performance in pain response on dressing removal for STSG donor site wounds. Large scale and well-designed randomised controlled trials should be conducted in the future to confirm the findings.
Reflective questions
- What factors should you take into consideration when selecting the appropriate dressing for split-thickness skin graft donor sites?
- How did Aquacel Foam dressing perform on split-thickness skin graft donor sites in this study compared with Aquacel?
- What are the implications for future research?