Instrumental Evaluation of the Protective Effects of a Barrier Film on Surrounding Skin in Chronic Wounds

     Abstract: Objective. This study investigated the effects of Cavilon® No Sting Barrier Film ([NSBF], 3M Healthcare, St. Paul, Minn) on skin surrounding chronic wounds by means of monitoring transepidermal water loss (TEWL). Methods. Forty patients were examined; 20 patients had pressure ulcers and the other 20 patients had venous leg ulcers. The patients were divided into 2 groups, the first group (treatment group) was treated with NSBF and the second group (control group) was treated with zinc oxide ointment applied to surrounding skin. TEWL values on surrounding skin were monitored before and after the therapy. Results. Statistical evaluation showed an overall reduction of 45% in TEWL values in both groups by the conclusion of the study period when compared to baseline values (P < 0.01). The NSBF application was a quick and simple process. Removal of residue was not necessary. An additional benefit is that the skin can be seen through the film. Conclusion. The study objectively demonstrated that the NSBF can help in the management of the skin surrounding chronic wounds.      The concept of moist wound healing is widely applied in the treatment of chronic wounds. The benefits of a moist healing environment seem to result from epidermal migration, alterations in pH and oxygen levels, the maintenance of an electrical gradient, and the retention of wound fluid. The level of wound moisture is related to several factors. These factors include wound type, phase of wound healing, and absorptive capacity of local dressings.¹      A high level of exudate is a commonality among patients with chronic ulcers, often resulting in surrounding skin maceration, subsequent damage to the exposed tissue, and enlargement of the wound.² Use of protective products can prevent skin damage. Zinc oxide ointment is often used to protect the surrounding skin, but is difficult to remove because a white layer remains on the skin, causing problems in the assessment of wound edges. The aim of the present randomized control trial was to investigate the effects of 2 different types of protective products on the barrier integrity of skin surrounding chronic wounds using an instrumental device to assess transepidermal water loss (TEWL).      TEWL is one of the most important biophysical parameters for evaluating the efficiency of the water barrier in human skin.³ Patients and Methods Forty patients (27 women, 13 men), age range 56–86 years (mean 69 ± ⁴) who were attending the wound clinic for treatment of chronic venous leg ulcers and pressure ulcers were examined prospectively.      Venous leg ulcers. Twenty patients with venous leg ulcers were included. The mean wound duration was 16 months and the median wound size was 47.5 cm². All patients were sequential and nonselected. All had clinical and laboratory evidence of venous insufficiency as defined by the following criteria: presence of varicosities, skin hyperpigmentation, irregularly shaped ulcerations on the medial aspect of the leg, and venous reflux confirmed by Doppler flow studies. In addition, patients with arterial insufficiency were excluded who had an Ankle Brachial Pressure Index (ABPI) measurement > 0.8. Patients with diabetes, advanced small vessel disease, and ulcers with clinical signs of infection were excluded. Patients received standard treatment including short stretch compression bandaging and moist wound healing treatment. Pressure ulcers. Twenty patients with pressure ulcers (Grade II–IV) were included. The mean wound duration was 8 months and the median wound size was 5.7 cm².      Clinical signs of infection served as exclusion criteria. Patients received standard treatment, including pressure redistribution and moist wound healing treatment. After signing a consent form, the patients were randomized to receive either zinc oxide or Cavilon® Barrier Film (3M Healthcare, St. Paul, Minn) and were treated every 48 hours for 4 weeks. The barrier film was changed every 48 hours. The NSBF is a transparent and easy-to-handle film that protects the wound edge. The film is a sting-free, alcohol-free, liquid barrier film that dries quickly to form a breathable, transparent coating on the skin.      Transepidermal water loss (TEWL) measurement. Measurement of TEWL was made at the same site for all patients using VapoMeter® (Delfin Technologies Ltd., Kuopio, Finland). This instrument is a hand-held, battery-operated device with a closed cylindrical chamber that contains sensors for relative humidity (RH%) and temperature (˚C). The closed chamber conditions are created upon skin contact with a surface area of 1-cm diameter and are thus unaffected by ambient airflows. Measurement time is between 8 and 10 seconds. Values of ambient RH% and temperature are recorded before skin contact, and the chamber is passively ventilated between measurements.⁴ For measurements, the meter was used at standard room ambient conditions (25˚C, 55% RH) and 3 consecutive readings were taken at the same site using mean values. Control measurements for TEWL were taken on normal skin in the hairless, upper chest area of each subject.

Results

     The key issue addressed in this study relates to the objective ability of 2 products (zinc oxide ointment and NSBF) to maintain surrounding skin integrity, which was done by measuring TEWL. A significant difference in mean TEWL values between skin surrounding the wound and the control area was observed in all patients at baseline (P < 0.001, [Figure 1]).      Statistical evaluation showed a 45% overall reduction in TEWL values in both groups at the end of the study period compared to baseline values (P < 0.01, [Figure 2]). The pressure ulcer group treated with NSBF had an initial mean TEWL value of 202.5 g/m2h and 113.4 g/m2h after 4 weeks (P < 0.05). The patients treated with zinc oxide ointment had a baseline TEWL value of 60.2 g/m2h and 30.4 g/m2h at the end of treatment (P < 0.05).      The venous leg ulcer group treated with NSBF had an initial mean TEWL value of 75.3 g/m2h and 49.7 g/m2h after the treatment; in the patients treated with zinc oxide ointment the initial TEWL was 60 g/m2h and 33 g/m2h after 4 weeks (Figures 3a, 3b).      The NSBF was quick and easy to apply and did not require any residue removal (Table 1). Additionally, the skin could be seen through the film. Zinc oxide requires a mineral oil or an oil-based emollient to facilitate removal; rubbing the paste to remove it can cause trauma to the periulcer skin.

Discussion

      A moist wound environment is fundamental for optimal wound healing.⁵ Despite its provision for optimal healing, a moist environment can cause damage to the perilesional skin barrier, delay healing, and lead to other complications. Recently Walker et al⁶ demonstrated that the periwound skin barrier was compromised. Variability in the water permeability values for periulcer tissue, together with histological images, confirmed that the presence of an impaired skin barrier in such tissue is likely the result of the effects of wound exudate on the tissue. When the skin barrier is damaged, the passive diffusion of water from the deeper skin layers to outside TEWL increases; even subtle changes in barrier integrity can be detected by measuring TEWL. This noninvasive technique is applicable in vivo and offers the possibility to quantify periulcer skin responses after the application of protective products.⁷ It should therefore be possible to administer agents to the wound periphery, which would permit a more efficient water delivery through the skin.      It is particularly important to protect the surrounding skin from maceration caused by exudate, because this reddens the wound edges and makes it difficult to attach the dressing material. Progress in the management of wound edges has generally been unsatisfactory and in many cases the products used have not been developed with the aim of skin protection. The lack of supporting clinical evidence creates difficulties for caregivers in prescribing the most effective treatment.      Shuren et al⁸ published a review, which demonstrated that there is no statistically significant difference between the protective properties of different periwound skin barriers. Coutts et al⁹ observed that zinc oxide and petrolatum are effective, but can interfere with the dressing’s absorption and adhesion. Several reports have confirmed that zinc oxide and petrolatum are difficult to remove.¹⁰ Most studies conclude that more research is needed to determine the objective efficacy of the products used to protect surrounding skin. In the literature, only 1 intra-individual, double-blind, randomized trial objectively demonstrated the efficacy of a film barrier on perilesional skin using a chromometer to measure erythema, which could detect color changes not visible to the naked eye.¹¹ The erythema completely disappeared after 3 days in 88.1% of the patients and after 4 days in all patients when treated with NSBF.      In the present study, the skin barrier was monitored by measuring TEWL during treatment with 2 types of skin protective agents in order to achieve an objective efficacy evaluation of the skin barrier product.

Conclusion

     The results of this study showed that TEWL measurements are the most important biophysical parameters for evaluating the efficiency of the human skin water barrier and that the NSBF and zinc oxide ointment helped improve the surrounding skin barrier. As an additional benefit, the NSBF was easy to apply—therefore reducing patient discomfort and suffering.