A laboratory comparison between two liquid skin barrier products

Abstract

Exposure of skin to friction and moisture is detrimental to skin health. The purpose of this experimental study was to investigate the ability of a cyanoacrylate polymer film to protect human skin against moisture and abrasion. A secondary purpose of this study was to compare this cyanoacrylate material to a traditional barrier film. Twelve healthy subjects participated in the wash‐off resistance test to determine the percentage of dye that was left on the skin after repeated washing. Ten subjects participated in the abrasion test. Transepidermal water loss (TEWL) was measured before and after abrasion to determine the level of skin damage, as high water loss seen post‐abrasion is indicative of skin damage post‐abrasion. Skin treated with cyanoacrylate had significantly more dye remaining than sites treated with traditional film barrier or control sites. The change in TEWL was statistically lower for cyanoacrylate‐treated areas.

Introduction

The skin is the largest organ of the body, which functions as a mechanical, chemical and immunological barrier. Skin breakdown often predominantly categorised into superficial or deep based on differences in their contributing mechanisms. Mechanical forces such as pressure and shear are linked to deep tissue damage due to reduced blood flow, interrupting the delivery of oxygen and nutrients for cellular metabolism. Superficial lesions are often caused by excessive rubbing, friction and trauma that strip the skin. Prolonged and increased exposure to moisture from bodily fluids such as urine, loose stool, perspiration and caustic wound exudate, the surface of the skin becomes alkaline, overhydrated, macerated and soft, rendering it more susceptible to breakdown. Corrosive enzymes in faecal material are activated by ammonia released from the breakdown of urine, and they penetrate through the stratum corneum, leading to skin erosion, inflammation and further damage 1, 2, 3, 4. Common superficial skin lesions include stage 2 pressure ulcers, skin tears, incontinence‐associated dermatitis and moisture‐associated skin damage; they affect millions of individuals and cost millions of dollars every year 5. In addition, moisture‐associated skin damage has been documented to be associated with pain, secondary infection (e.g. intertrigo) and delayed wound healing when damage involves the wound edge and periwound skin 6, 7, 8. Provision of meticulous skin care and protection of vulnerable area from moisture and friction are critical to promoting skin health 9, 10, 11, 12, 13, 14. Application of barrier protectants based on petrolatum, silicone, zinc and acrylates, which create a physical barrier, has been incorporated into a number of best practice documents. Although these skin protectants are intended to minimise friction, repel fluid and protect the skin from chemical irritants, scientific evidence to substantiate their relative effectiveness remains inconsistent 8, 15, 16, 17. In a recent study, Woo 9 demonstrated that cyanoacrylate‐based barrier protectant is more cost‐effective than petrolatum barrier. Cyanoacrylates have been shown to form a polymer film quickly in situ on human skin and have been safely used to provide closure to surgical and traumatic wounds for several years 18, 19, 20, 21, 22, 23, 24, 25; they have also been used on peristomal 26 and pedal lesions 27 to successfully promote healing. However, to our knowledge no literature exists investigating the potential benefits from using a monomeric cyanoacrylate, as a tool to prevent intact skin from breakdown. While rare allergic reactions have been reported for certain preparations 28, 29, 30, 31, 32, application of cyanoacrylates to human skin and tissue is safe for most individuals and has U.S. Food and Drug Administration approval 33. The overall purpose of this study was to investigate the ability of a cyanoacrylate polymer film (Product A, Marathon^®; Medline, Mundelein, IL) to protect human skin against moisture and abrasion. A secondary purpose was to compare this product, in such a capacity, to a widely used solvent delivered, polymer acrylate product, marketed for similar purposes (Product B; Cavilon^® no‐sting barrier film, 3M^®, Minneapolis, MN).

Methods

This study consisted of two parts, each conducted on a separate group of healthy subjects with separate procedures and outcome measures. They will be presented separately in the Methods and Results of this article under the headings ‘Wash‐off resistance’ and ‘Abrasion’. In both parts of the study, Products A and B, defined above, were the products tested.

Wash‐off resistance

For this study, 12 subjects were recruited with the following inclusion/exclusion criteria. Subjects were excluded if they had any known sensitivities to cosmetics, soaps or fragrances. They were required to refrain from application of any moisturising products to their arms at any time on the study day or during the 3 days prior to the start of the study. Subjects were excluded if they had any marks, scars or scratches on the volar forearms. The average age of the subjects was 66·3 ± 3·2 years; in addition, there were 10 women and 2 men.

All subjects signed a consent form after being informed of their obligations and the risks that they might encounter as a participant in this study. The subjects reported to the lab and their arrivals were staggered. As subjects arrived, three 5 × 5 cm² sites, on each volar forearm, were outlined with a marker. Each site was stained with crystal violet, rinsed and patted dry. The stained site was allowed to dry for 10 minutes prior to any measurements and application of the test products.

The barrier film products were applied to four of the six stained sites in duplicate (each product was applied to one site on each arm) according to manufacturer's directions. A central site on each arm was stained, but no barrier film was applied, to serve as the controls. The barrier films were allowed to dry for 5 minutes prior to taking measurements and beginning the soak/wash cycles.

Saturated gauze squares with synthetic urine (Surine™; DYNA‐TEK Industries, Inc., Lenexa, KS) were used to soak the test sites by overlaying test sites with the gauze squares for 20 minutes. The forearms were wrapped with plastic wrap to keep the gauze pads in place and mimic the occlusive effects of a diaper against the skin. After each soak, the test sites were cleansed with Aloe Vesta^® Perineal/Skin Cleanser (Convatec, Greensboro, NC) according to the following procedure. Test sites were sprayed once each by a blinded researcher, who waited 10 seconds and then gently wiped the sites twice in an upward direction and twice in a downward direction with a Wypall cloth. The sites were not rinsed.

The colour of the test site, the outcome measure in this study, was measured with the DSM II Colorimeter (Cortex Technology, Hadsund, Denmark). The colour meter was calibrated prior to use at each time point, using a standard white tile. A researcher took the average of three measurements from each of the test sites at the measurement time points (Figure 1). Measurements were completed 30 minutes after each post‐soak wash. The first wash cycle began following the dye and film application and the completion of the colour measurements of the fully stained arm sites. Four additional wash cycles were completed following each of the colour measurements, which were taken at 30‐minute intervals, after each post‐soak wash (Figure 1).

Figure 1.

Flowchart of study methods.

A repeated measures ANOVA was run on the net change in colour measurement from full stain at baseline to that obtained at each subsequent time point, to compare the test barrier films and the stained/no film controls. A repeated measures ANOVA was also run to compare each film or stained/no film control versus its baseline (pre‐dye). For all analysis, an α level of 0·05 was taken as the level of significance for comparisons.

Abrasion

Ten subjects were recruited from a pool of healthy suburban women who meet the inclusion/exclusion criteria. The subjects were 69·1 ± 3·2 years of age. Each candidate was interviewed to make certain that they had no medical problems and were not using concomitant medications that might interfere with the study results. They were also screened to make sure that they had no known allergies to cosmetics, soaps or fragrances. In addition, subjects could not have any marks, scars, scratches, etc. on volar forearms and could not be going through menopause (i.e. experiencing hot flashes). Subjects were asked not to exercise on the day of the study prior to this visit.

All subjects signed a consent form after being informed of their obligations and the risks that they might encounter as a participant in this study. Each subject was instructed to stop the use of all moisturising products on their arms during a 3‐day pre‐conditioning period prior to testing. The subjects were instructed not to apply any other products, nor tamper with their arms in any way during the study period.

On the day of the study, each subject reported to the lab and a researcher logged in each panellist and outlined three 5 × 5 cm² sites on each arm. All subsequent study procedures were performed following a 15–30‐minute acclimation period in the lab, a controlled environment with the relative humidity maintained at <50% and temperature maintained at 21 ± 1°C. At baseline, evaporative water loss measurements were taken by a researcher from each of the test sites as described below. Any individuals with water loss values outside the normal range (>10·0 g/m² hour) would have been excluded at this time.

Transepidermal water loss (TEWL) measurements, the outcome measure in this study, were made using a recently calibrated DermaLab^® USB with TEWL probe (Cortex Technology). The instruments' probes contain sensors that measure the temperature and relative humidity at two fixed points along the axis normal to the skin surface. This arrangement is such that the device can electronically derive a value that corresponds to evaporative water loss expressed in g/m² hour. Water loss data from the evaporimeter were recorded at a sampling rate of eight inputs per second. The extracted value refers to the average evaporative water loss rate, collected over a 20‐second interval once steady‐state conditions had been achieved. The researcher who served as the instrument operator was not involved in any treatment aspects of this study so that the TEWL readings would be blinded.

According to manufacturer's instructions, a researcher applied the two test products to two of the three sites on each arm according to a randomisation schedule (Table 1). Four of the test sites were treated, while one, centrally located site on each arm, remained non‐treated to serve as a control.

Table 1.

Randomisation schedule for abrasion test sites on subject arms

Subject no.	RU	RC	RL	.LU	LC	LL
1	B	NoRX	A	A	NoRX	B
2	A	NoRX	B	B	NoRX	A
3	A	NoRX	B	B	NoRX	A
4	B	NoRX	A	A	NoRX	B
5	B	NoRX	A	A	NoRX	B
6	A	NoRX	B	B	NoRX	A
7	A	NoRX	B	B	NoRX	A
8	A	NoRX	B	B	NoRX	A
9	B	NoRX	A	A	NoRX	B
10	B	NoRX	A	A	NoRX	B

RU, right upper; RC, right centre; RL, right lower; LU, left upper; LC, left centre; LL, left lower; A, Product A; B, Product B; NoRX, control.

The test products were allowed to dry for at least 3 minutes before the abrasion test was started. In order to challenge the test sites in a consistent manner, a researcher rubbed a Scotch‐Brite Delicate Duty Scrub Sponge over each site 10 times in the same direction for all sites. TEWL readings were taken at baseline and immediately following abrasion.

A repeated measures ANOVA was run to compare the average values for the net change from baseline TEWL measurements, which occurred with each product, and the non‐treated control. A Tukey–Kramer multiple comparisons test was then performed, a post hoc test to determine how significant these differences were among the various treatment groups. For all analysis, an α of 0·05 was taken as the level of significance for comparisons.

Results

Wash‐off resistance

At baseline, with the dye and product applied, the colour measurement for the control sites had a mean = 14·83 and SD = 2·16, for sites with Product B the mean = 15·28 and SD = 1·79 and for sites with Product A the mean = 15·80 and SD = 2·50. This is compared with the readings after the five wash cycles, where control sites had a mean = 27·51 and SD = 3·20, for sites with Product B the mean = 20·52 and SD = 2·52 and for sites with Product A the mean = 16·69 and SD = 2·66. When expressed as a percent of the dye remaining on the skin, these differences reveal that the control sites finished with only 17·90 ± 10·22% remaining, sites treated with Product B had 66·09 ± 9·49% remaining and sites treated with Product A had 93·59 ± 5·65% of the dye remaining (Table 2).

Table 2.

Average percent dye remaining during the wash‐off test.

	Control		Product B		Product A
	Mean	SD	Mean	SD	Mean	SD
Baseline	100	n.a.	100	n.a.	100	n.a.
Post‐wash cycle 1	63·3*	11·8	95·6	1·9	101·3	3·9
Post‐wash cycle 2	42·6	12·6	90·4	5·2	98·7†	4·0
Post‐wash cycle 3	31·4	12·9	84·5	5·9	97·3†	6·1
Post‐wash cycle 4	23·1	11·0	75·2	6·5	95·4†	5·7
Post‐wash cycle 5	17·9	10·2	66·1	9·5	93·6†	5·7

n.a., not applicable.

^*Significant difference comparing control with Product A and Product B.

^†Significant difference comparing Product A with Product B.

There was a statistically significant difference among the percent dye remaining means after each soak wash cycle (Table 2). The Tukey–Kramer multiple comparisons tests revealed that after the first soak wash cycle, there was no difference between Product A and Product B, q = 2·90, P> 0·05; however, there was a difference at each subsequent measurement where the sites treated with Product A had significantly more dye remaining than sites treated with Product B or control sites (Table 2; Figure 2).

Figure 2.

Percent dye remaining after each soak wash cycle in the wash‐off test. [Correction added on 29 August 2014, after first online publication: the labels, Product A and Product B in Figure 2 were interchanged and have now been corrected.]

Abrasion

At baseline, before product application, the TEWL measurements for the control sites had a mean = 4·08 and SD = 0·85, for sites with Product B the mean = 3·94 and SD = 0·86 and for sites with Product A the mean = 4·05 and SD = 0·90. This is compared with the readings after product application and abrasion, where control sites had a mean = 7·12 and SD = 1·33, for sites with Product B the mean = 6·61 and SD = 1·16 and for sites with Product A the mean = 6·18 and SD = 1·15. When expressed as the difference between baseline and post‐abrasion, the control sites changed by 3·04 ± 0·80, sites treated with Product B changed by 2·67 ± 0·76 and sites treated with Product A changed by 2·13 ± 0·79 (Table 3).

Table 3.

Change in transepidermal water loss during the abrasion test

Subject no.	Control	Product B	Product A
1	2.2	2.6	2.2
2	3.0	2.3	0.9
3	2.9	2.6	2.7
4	2.9	2.5	1.3
5	4.9	4.0	3.4
6	2.6	1.3	2.1
7	3.7	3.6	2.9
8	3.4	3.2	2.7
9	2.3	2.3	1.7
10	2.6	2.4	1.5
Mean	3.04	2.67	2.13*
SD	0.80	0.76	0.79

^*Significant difference comparing control with Product B.

There was a statistically significant difference among the means of change in TEWL, F = 12·4, P = 0·0004. The Tukey–Kramer multiple comparisons tests revealed that there was a statistically significant difference between mean TEWL change at sites treated with Product B compared with those treated with Product A, q = 4·16, P < 0·05, and between the mean at sites treated with Product A and the mean for control sites, q = 7·01, P < 0·001; however, there was no difference in the mean TEWL change for the sites treated with Product B compared with the mean change in TEWL at the control sites, q = 2·86, P > 0·05 (Table 3, Figure 3).

Figure 3.

Pre‐ and post‐transepidermal water loss (TEWL) means for the abrasion test.

Discussion

The overall purpose of this study was to investigate the ability of a cyanoacrylate monomer, which forms a tough, flexible film on skin, to protect human skin against moisture and abrasion. The results from the study revealed that when intact human skin was exposed to repeated cycles of urine soaking (synthetic urine was used) and washing, crystal violet staining (a proxy way to track stratum corneum assault) was gradually removed without causing any damage to the skin. Skin protected by the two different products in this study retained staining better than unprotected skin. Skin protected by Product A was the most resistant to loss of the stain. This indicates that the stratum corneum can be protected from exposure to moisture, potentially even urine, by prophylactically applying this product. In addition, the results indicated that abrasive trauma to intact skin elevated the level of TEWL (a proxy measurement for skin damage), but retarded the rate of loss by using a barrier. Of the two products used in this study, Product A was significantly better at protecting the skin from abrasion, resulting in lower TEWL.

Liquid barrier film made of polyacrylates has been used safely for some time to protect vulnerable skin, and there are good clinical trials supporting the efficacy of this modality 7, 8. A recent meta‐analysis reported that the acrylate polymer might not produce clinical outcome superiority over traditional products, but that it does offer ease of use and tissue visualisation advantages 8. If the results from this laboratory study prove translatable into clinical scenarios, it would be expected that superiority of Product A to other traditional products for skin protection would be demonstrated. Clinical studies must be carried out to establish this conclusively.

The results of the wash‐off portion of the study provide evidence for the persistence of cyanoacrylate polymers compared with more traditional acrylate polymers. Although there was no difference between the products after the first soak wash cycle, a difference did appear at each subsequent measurement, wash soak cycles 2 through 5. This finding would indicate that either product could offer protection against exposure to moisture when first applied, but that Product A could be reapplied less frequently. Although not tested in this study, it would be likely that the amount of product needed and the time taken by health care provider to apply the product would be less for Product A. This may result in a difference in the cost of use for the products. Future study is warranted to examine and validate the cost‐effectiveness.

This study provides evidence for the use of prophylactically applied cyanoacrylate monomer, which is known to form a polymer film quickly in situ, to protect skin. In addition, during this study none of the 22 persons exposed to Product A had any adverse reactions. This study used objective and precise tools to measure the impact of wash soak cycles and abrasion on healthy skin. However, it is not known how directly these measurements would translate into clinical outcome measures such as erythema and maceration. TEWL has been used extensively as an outcome measure in other studies of skin health and barrier function, but the persistence of crystal violet staining needs more study to determine its clinical translatability.

Extensive literature exists to show that skin exposure to moisture and friction is a significant risk factor for pressure ulcer development. In addition, it leads to MASD and periwound maceration. Some reports have been presented recently in journals and at conferences, which begin to support the validity of using cyanoacrylate to treat periwound maceration in persons with leg ulcers, pedal fissures, peristomal skin breakdown, and to prevent pressure ulcers on the heels of non‐ambulatory patients 6, 27, 34, 35, 36, 37. These clinically based reports, combined with this laboratory study, provide a strong foundation for future controlled clinical trials to validate these findings.

Conclusions

Product A, a cyanoacrylate polymer film, was effective in protecting human skin against moisture and abrasion. In addition, Product A was more effective than Product B for the same purposes. During the wash‐off test, Product A was demonstrated to have persistence of protection. The ability of a single product to protect skin from repeated cycles of washing and urine exposure carries tremendous clinical potential. Clinical outcome studies are needed to determine whether these findings result in reduced rates of MASD or pressure ulcer. Cost‐effectiveness studies are also warranted, given the persistence demonstrated by Product A in this study.