Pressure Garment Therapy For Burn Scar Management

It can be frustrating for a burn survivor to deal with issues of scarring even after the initial burn injuries have healed. The most common complication of a burn injury is that of raised scars in the area of the original burn, technically known as 'hypertrophic burn scars' ^[1] . Such scars can limit the survivor's ability to function and also make the person depressed due to the overall body image.

According to various researches, burns that heal within 14 days usually do not leave any scars behind. However, severe burns that heal within 14 to 21 days might put you at risk of scarring. Burns that take more than 21 days to heal, are high-grade, high-risk ones and might require skin grafting ^[2] .

Why Do Burn Scars Form

The depth and location of the burn play a major role in determining the intensity of a burn scar. Scars tend to occur when the dermal or lower layer of the skin gets damaged. The human body is capable of forming a protein known as collagen. This protein helps in healing any damaged skin. However, in the case of hypertrophic scars, the collagen fibres are not laid in an organized manner ^[3] . This results in the formation of a scar. It takes time for the scars to fade (about 12 to 18 months). As the scars mature, they become flat, soften and fade in colour.

Characteristics Of Hypertrophic Burn Scars

Hypertrophic scars are considered to be systemic inflammatory illnesses that are regulated by local wound healing factors ^[4] . This is more common in burn survivors who have delayed healing. Such scars can lead to lifestyle-limiting problems such as burning, stiffness, pain and contractures in some cases.

The following are the characteristics of hypertrophic burn scars ^[5] :

• They stay within the area of the original burn injury
• They appear reddish or purplish in colour
• They are raised above the surface of the skin
• They develop within the first few months after the injury
• They are itchy and can be warm to touch
• They are more noticeable and prominent around the joints, regions where the movement is high.
• They are highly sensitive to sun

Prevention and treatment of such scars are one of the most serious issues in burn rehabilitation. Successful management depends on the early and aggressive treatment.

Treatment Of Hypertrophic Burn Scars

The conventional technique of treating hypertrophic burn scars involves using pressure therapy ^[6] . This therapy involves wearing garments made from elasticized fabrics. Dating back to the early 1970s, pressure garments have evolved as one of the most noninvasive scar management options. Experts have reached a general consensus on the use of pressure garment therapy (PGT). This procedure has been widely accepted as a clinically accepted practice.

Currently, PGT is the first-line therapy for hypertrophic burn scars in most of the rehabilitative centres worldwide. This has been accepted as the standard treatment methodology considering its non-invasive characteristics and desirable treatment effects with minimal complications ^[7] .

Although a lot of contradictory opinions exist, experts recommend that the pressure of the compression garments should be maintained between 20 and 30 mm Hg [8] .

Using Pressure Garments - Advantages & Disadvantages

Medical experts suggest custom-made elastic pressure garments (also known as compression garments) as they are most effective and comfortable for people with hypertrophic scars. For scars on the face, the pressure is better exerted when the pressure garments are custom-made. For facial scarring, transparent plastic face masks are used. To see results, it is necessary that PGT is followed for a minimum period of 6 to 12 months. It is recommended that the patients keep the pressure garments on for 23 hours daily. Also, PGT shows better result when it is initiated prophylactically as early as possible (around 2 weeks after the wound closure) ^[9] .

In spite of the benefits that PGT promises, many refrain from using them especially due to them being expensive and also as they look unattractive. In some rare cases, PGT has seen issues such as overheating, blistering, wound breakdown and abnormal bone growth ^[10] . Moreover, wearing pressure garments can get quite uncomfortable in hot and humid climates.

Fabrication Of The Pressure Garment

It is essential to make a note of the point that 'pressure' plays an important role while fabricating a compression garment. Also, the pressure that the garment would exert is dependent on the fabric tension per unit length and its anisotropic behaviour. The number of fabric layers used for the construction of the garment is also a deciding factor. The fabric gain direction must also be aligned with the stretching direction ^[11] .

The following are the two methods followed for constructing pressure garments ^[12] :

1. The reduction factor method: This is the one that is most commonly used. The patient's circumferential measurements are reduced by a certain percentage. This does not take into account the fabric tension (when calculating garment dimensions).

2. Method using Laplace's law: This involves the fabrication based on the tension profile of the fabric and the circumferential measurements of the patient. This method is more accurate as the range of pressures that can be applied to a particular body part keeps varying depending on the fabric used along with the fabric's tension-extension profile.

Once the circumferential dimensions of the required body part are obtained (using a measuring tape), pressure garments are fabricated based on the standardized reduction factor method (10, 15 or 20 per cent applied to the patient's measurements). The reduction factor remains constant throughout. The garments are cut and developed from elastic fabrics (usually made from nylon/elastane filaments). The more accurate the measurements, the better it fits the patient.

Pressure garments can generate an increase in subdermal pressures in the range of 9 to 90 mm Hg (this is dependent on the anatomical site). Garments that are placed over soft tissues generate pressure that ranges from 9 to 33 mm Hg. On bony areas, the pressure generated ranges from 47 to 90 mm Hg ^[13] .

Nevertheless, it should be noted that pressure garments lose tension and hence its pressure-delivering ability over time and with constant use. To maintain adequate pressure, it is recommended that these garments are replaced every 2 to 3 months.

Compression And Its Effect On Hypertrophic Scars

The compression offered by the pressure garments is said to produce regression of hypertrophic scars ^[14] (in at least 85 per cent of the patients).

The working of pressure garments relies on two main concepts:

1. Restriction of blood flow to the scar area ^[15]
2. Constant compression to inhibit the growth of hypertrophic scar tissue ^[16]

It is believed that pressure may facilitate scar maturation and control collagen synthesis. This is made possible by limiting the blood supply, oxygen and nutrients. This facilitates a reduction in scar redness and oedema ^[17] .

Collagen production is also reduced to levels found in normal scar tissue more rapidly than what can be expected with the natural maturation process. There is an alteration in collagen fibre turnover along with remodelling and realignment. These reduce the development of whorled collagen nodules, thus resulting in softening and thinning of scar tissues ^[18] .

The threshold of the effective daily application period for pressure therapy is determined by the pressure levels. Longer application periods are required in case of garments with low applied pressures.

Importance Of Patient Compliance For Pressure Garment Therapy

Making pressure garment therapy work requires significant and long-term patient involvement and cooperation. This is so because how effective the pressure garments would be is highly dependent on the daily duration of applied pressure for a long period (several months). Patients might be sceptical about using pressure garments due to various reasons, some of them being ^[19]

• lack of comfort
• restricted movement
• swelling of extremities
• development of rashes/blisters
• bulky appearance
• improper fit

Clear practice guidelines along with follow-up procedures when patients meet experts in the out-patient rehabilitation services may help improve patient compliance to a great extent. Social support along with a good doctor-patient relationship is also highly essential to help motivate patients such that they continue to follow the therapy.