Can Single Use Negative Pressure Wound Therapy be an alternative method to manage keloid scarring? A preliminary report of a clinical and ultrasound/colour‐power‐doppler study

Abstract

Keloid scarring represents a pathological healing where primary healing phenomenon is deviated from normal. Pico is a single use negative pressure wound therapy system originally introduced to manage open or just closed wounds. Pico dressing is made of silicone, and distributes an 80 mmHg negative pressure across wound bed. Combination of silicon layer and continuous compression could be a valid method to manage keloid scarring. Since November 2011, three patients were enrolled and evaluated before negative pressure treatment, at end of treatment (1 month) and 2 months later, through Vancouver Scar Scale (VSS), Visual Analog Scale (VAS) and a scoring system for itching. Ultrasound (US) and colour‐power‐doppler (CPD) examination was performed to evaluate thickness and vascularisation of the scar. One patient was discharged from study after 1 week. In last two patients, VSS, VAS and itching significantly improved after 1 month therapy and the results were stable after 2 months without any therapy. At end of therapy, the ‘appearance of palisade vessels' disappeared in both cases at CPD exam; US showed a thickness reduction (average 43·8%). We propose a well‐tolerated, non invasive treatment to manage keloid scarring. Prospective studies are necessary to investigate whether these preliminary observations are confirmed.

Introduction

Keloid scarring represents a pathological healing in which the primary healing phenomenon is deviated from normal process. Patients suffer from cosmetic disfigurements, pain, itching and inflammation. Several treatment options have been proposed (1) including steroids, surgical excision, irradiation, silicone gel, pressure therapy, laser, other intralesional injections (5‐fluorouracil, interferon, retinoids, calcium channel blockers, cryosurgery, antihistamine, penicillamine and colchicines) and multiple combinations of those treatments.

The authors present a new indication for a negative pressure device that combines pressure therapy and silicone sheets, aiming to reduce signs and symptoms of keloid scars.

Methods

Since November 2011, we enrolled for this study three patients with keloid scarring. This work should be attributed to the University of Turin, Plastic Surgery Unit, Hospital S. Giovanni Battista of Torino, Italy. Inclusion criteria were: keloid scarring from more than 1 year and never received previous treatment for keloids in the past. Exclusion criteria were: pregnancy, scar in the face and suspected silicone allergy.

Two patients were female, one male, with range 7–38 years old; they suffer of keloid scarring in the deltoid (patient 1), scapular (patient 2; Figure 1) and dorsum of the hand (patient 3); at the time of enrollment, keloid was present from a period of time ranged between a minimum of 18 months to a maximum of 18 years. Aetiology was due to vaccine (deltoid region), pustular acne (scapular region) and to burn accident (dorsum of the hand). The dimension of keloids ranged from 5 × 2·5 cm (scapular area) to 7 × 3·5 cm (dorsum of the hand).

Figure 1.

Patient 2, pre‐treatment photography, presenting a scapular keloid.

The smallest size of Pico™ (Smith&Nephew, Hull, UK) device was positioned over the keloid scar and the surrounding healthy skin.

Pico™ is a single use negative pressure wound therapy system originally introduced to manage open or just closed wounds. Pico™ is composed of four layers dressing in which the deepest one (in contact with the lesion) is made of silicone. The dressing is connected through a tube to a pump that distributes an 80 mmHg negative pressure therapy across the wound bed. After 7 days, it is necessary to change pump and dressing. In this way, Pico™ does require replacement only once a week. In this trial, it was chosen to apply this device for 1 month therapy. Every week the dressing and the pump were replaced, four times in a period of 4 weeks. Patients were evaluated before the negative pressure treatment, at the end of treatment (1 month; Figure 2) and 2 months after the ending of the treatment (during that period, no other therapy for keloids was prescribed). Changes in scar appearance were evaluated with Vancouver Scar Scale (VSS) (2), pain was recorded with Visual Analog Scale (VAS) (3) and a scoring system with one to three plus (+) was given for scar itching. Furthermore, for every patient, ultrasound (US) and colour‐power‐doppler (CPD) examinations were performed to evaluate both thickness and vascularisation of the keloid scar. The evaluations of VSS, VAS and itching were made by the same clinician (MF). In the same manner, the US and CPD examinations were made by the same radiologist (AS), employing a Mylab 70 device (Esaote, S.p.A., Genoa, Italy) supported by a high‐frequency linear probe (7–10 and 10–13 MHz).

Figure 2.

Patient 2, after 1 month of treatment with Pico device.

The thickness of the scar was evaluated in three different points of the same keloid; the reported measurement taken into account for this study was the highest measured value (the thickest part of the keloid).

The study protocol is conformed to the ethical guidelines of the 1975 Declaration of Helsinki. Informed consent was obtained from each patient.

Results

One patient (a young child with keloid on the dorsum of the hand) was discharged from the study after 1 week, due to difficult management of the negative pressure across the dressing, pain and finger oedema. Results of VSS, VAS, itching and keloid thickness (before and after 1 month of treatment, and after 2 months of treatment) are summarised in Table 1.

Table 1.

Characteristics of the patients and results before treatment, after 1 month from treatment and after 2 months after the end of treatment with Pico device

	Keloid site	Aetiology	VSS; VAS; itching and thickness, before treatment	VSS; VAS; itching and thickness, 1 month at end of treatment	VSS; VAS; itching and thickness, 2 months after end of treatment
Patient 1	Deltoid	Vaccine injection	VSS 8	VSS 5	VSS 5
			VAS 9	VAS 6	VAS 6
			Itching +++	Itching +	Itching +
			0·49 cm	0·32 cm	0·27 cm
Patient 2	Scapular	Pustular acne	VSS 10	VSS 6	VSS 6
			VAS 3	VAS 3	VAS 3
			Itching ++	Itching +	Itching +
			0·42 cm	0·27 cm	0·24 cm
Patient 3	Dorsum hand	Burn accident	VSS 12	Stopped after 1 week	–
			VAS 7
			Itching +++
			0·67 cm

VAS, Visual Analog Scale; VSS, Vancouver Scar Scale.

In particular, improvement in VSS, VAS and itching was reported after 2 weeks of treatment and was stable after 2 months after the end of the treatment. Reduction of keloid thickness was reported at the end of the treatment and a further unexpected improvement was found after 2 months from device removal. In all cases, CPD showed typical ‘appearance of palisade vessels' before treatment (Figure 3). After 1 month of treatment, as after 2 months after the end of treatment, no more ‘appearance of palisade vessels' was found. Pico was well‐tolerated and both patients requested to continue negative pressure therapy. During last US thickness measurement, a reduction of 44·8% and 42·8% of pre‐treatment thickness was reported (4, 5, 6).

Figure 3.

Colour‐power‐doppler echography of the keloid of patient 2, showing ‘appearance of palisade vessels'.

Figure 4.

Ultrasound echography, showing pre‐treatment keloid thickness of patient 2. The thickness is 0·42.

Figure 5.

Ultrasound echography, showing keloid thickness of patient 2 after 1 month of treatment with Pico device. The thickness is reduced to 0·27 cm.

Figure 6.

Colour‐power‐doppler and ultrasound echography of keloid of patient 2 after 2 months after treatment with Pico device. No more ‘appearance of palisade vessels' is observed and the thickness is reduced to 0·23 cm.

Discussion

Every year in the world 100 000 000 patients present new scars (4), which 4·5–16% can develop in keloids or hypertrophic scarring (5). In particular, occurrence of keloids after burn injury is very high 6, 7. The physiopathogenesis of keloids scars is not well understood (8). However, keloid formation has been ascribed to altered growth factor regulation, aberrant collagen turnover, genetics, immune dysfunction, sebum reaction and alteredmechanics, but no single unifying hypothesis adequately explains keloid formation (1). Abnormal scars often occur at specific sites like the anterior chest, shoulder, scapula and lower abdomen (9), but rarely occur on the scalp and the anterior lower leg. These sites have bones lying directly under the skin, and therefore, such sites are rarely subject to mechanical tension. The site specificity suggests the main role of the mechanical forces applied to a scar, promoting their growth 10, 11. Furthermore, extracellular matrix and extracellular fluid produce intrinsic mechanical forces, tension, shear forces, osmotic pressure and hydrostatic pressure. When applied to cells, the mechanical stimuli are translated into electrical or chemical signals (12). In fact, mechanoreceptor‐related and mechanosensitive nociceptor‐related cellular events have been recently theorised to be a mechanism in keloid formation and pain (13). Various therapies have been proposed as treatment for keloids (1) but only two of them (silicone sheets and compression therapy) have various proprieties, that include regulation of mechanical forces on the scar. The innovation of the Pico™ as a new indication in keloid treatment is to combine in a single device a silicone‐based sheet with a compression therapy simplifying the management with a single replacement per week.

Randomised controlled trials have shown the efficacy of silicone gel and sheet 14, 15 and (along with intralesional corticosteroid injection) it is one of the evidence‐based treatments recommended by the International Advisory Panel on hypertrophic scar and keloid management (16).

Although its mechanism of action is not completely known, it transfers the tension from the border of scars to the lateral edge of the silicone gel sheet (17).

Moreover, it acts as an impermeable membrane that keeps the skin hydrated, similar to the stratum corneum (18), altering tissue oxygen level, producing pressure and temperature changes (13).

Silicone gel can be used alone or as adjuvant therapy after excision and is effective after 4–6 months of treatment (1).

In this study, Pico™ device reached excellent results with only 1 month of treatment, therefore, potentially reducing the necessity of prolonged treatments. No complication was observed; in particular, the negative pressure applied may reduce the possibility of skin maceration.

In fact, problems associated with silicone sheets therapy include moisture accumulation that can lead to skin maceration, persistent pruritis, skin rashes and odours (19).

Compression is reported to produce regression of hypertrophic scars in 60–85% of patients (20).

Even if the mechanism of pressure therapy has not been determined, cellular mechanoreceptors may be critical to the high success rate of compression therapy, due to the reduction of tension forces, affecting collagen production and organisation, and to cellular apoptosis (20).

Moreover, compression regulates temperature, oxygen tension and hydration (21), including the direct reduction of tissue perfusion and oedema, decreasing collagen synthesis, increasing prostaglandin E2 release and increasing activation and releasing of matrix metalloproteinases (13).

Compression garments are wrapped around the body to exert circular compression and to decrease volume. Standard application consists in 24 and 30 mmHg for 6–8 months (1) for 8–24 hours a day (22). The standard treatment usually lasts for approximately 1 year, the entire period of scar maturation (23).

Traditional compression therapy is ultimately limited by the ability to adequately fit the garment to the wounded area (24).

This limitation also applies to Pico™ device, especially in mobile and angled anatomical sites such as dorsum of the hand, but the vantage is that the applied pressure is localised to the dressing and does not necessitate circular compression (with traditional compression, pressures greater than 40 mm Hg can cause skin maceration and paresthesias (25)). The Pico™ device applies a negative pressure to the skin surface area, resulting in a positive compression on the keloid scarring. The positive pressure has not been measured.

The Pico™ limitation is mostly related to the maintaining of the negative pressure, especially in some anatomical site such as earlobe, cheek or the dorsum of the hand (cause of the patient 3 dischargment).

Vascularisation of keloids is still poorly understood; in keloids microvascular communication is lacking, capillary density is lower and vascular morphology is flatter (26), resulting in a palisade appearance at CPD study.

In this study, good results have been achieved with 1 month of therapy, possible change in treatment protocol may include the prolongation of the application of the device for a total of 3 months, with a pause of a week every month.

Conclusions

Silicone and compression therapy have been already described to be a valid treatment in keloid scarring. We propose an alternative, well‐tolerated, non invasive treatment to manage keloid scarring with a single device (Pico^™ that has proprieties of both silicone sheet and compression therapy. Prospective studies are necessary to investigate whether these preliminary observations are confirmed.

Acknowledgements

The authors have no conflicting interests to disclose.