Burn Wound Healing Considerations and Recovery Care Interventions

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Introduction

It has been well documented throughout wound journals that wound “healing” does not stop when re-epithelialization has been accomplished.  The remodeling and strengthening of the skin and underlying tissue, and maturation of the scar that results from deeper burn wounds, continues for months to years after visible closing has occurred.  Care of the skin and soft tissue during the remodeling phase is of paramount importance to ensure the best possible outcome- both cosmetically and functionally.

Unfortunately, there is very little documented, either evidence-based or in case reports, to describe the best care for burn wounds that are not managed surgically but are allowed to close secondarily.  This mainly includes those burn wounds that are expected to re-epithelialize within 3 weeks - the superficial partial thickness burn wound for the most part as well as the partial thickness burn wounds that are allowed to re-epithelialize before any deeper burn wounds may be considered for grafting.

Burn Wound Healing Physiology

Epithelialisation

"Epithelialization is a process of covering defect on the epithelial surface during the proliferative phase that occurs during the hours after injury. In this process, keratinocytes renew continuously and migrate upward from the basal to the differentiated layers. A continuous regeneration throughout homeostasis and when skin injury occurs is maintained by the epidermal stem cells ... Epithelialization is the most essential part to immediately reconstruct skin barrier in wound healing where keratinocytes undergo a series of migration, proliferation and differentiation."

Superficial partial thickness wounds:

• Epithelialization occurs as the proliferative phase draws to an end and the remodeling phase begins to develop. 
• There is a significant decrease in the amount of exudate being released from the wound, and the risk of infection decreases as the immunological functions begin to normalize. 
• The initial epithelial resurfacing is a thin, single layer of keratinocytes, almost transparent to the naked eye.  Gradually the epidermis will mature to the stratified, multi-cell layered structure that provides the barrier functions of the skin.  The other factor that renders the new epithelium fragile is the flattening of the dermal-epidermal junction.  The convolution of this structure (Rete ridges) re-develops over time and the collagen attachments between the dermis and epidermis re-form, lending strength and integrity to the skin.  The skin appendages (hair follicles, sebaceous glands and sweat glands) also eventually return to normal functioning. 
• No granulation tissue is generated and these burn wounds generally heal without scars.  
• All of this “normalization” of the skin may take up to 1 year to finish.

Burn injuries of indeterminate depth or deep partial thickness wounds:

• involve damage deeper into the dermal layer and may destroy many of the skin appendages.  Full thickness burns eliminate all of the dermal appendages. 
• Healing of these burn injuries involve scar formation which never regains the normal structure and function of the skin.  Even in the presence of a skin graft, the skin in the area of a graft never fully recovers to its normal state.  The sequelae of burn scars will be discussed below.

Burn Wound Care During Re-epithelialisation

Care of the burn wound as it is re-epithelializing is critical to allow the new epidermis to resurface the burn and mature.  Any trauma or changes in the wound environment may delay or prevent ongoing epithelialization or cause deterioration of new epithelium. 

This care includes use of nonadherent dressings that minimize evaporative water loss while not causing a situation where the wound may be too wet.  Decreasing the frequency of dressing changes also minimizes the risk of causing trauma to the fragile new epithelium.  Discontinuing the use of silver-based dressings, shown in many studies to delay the proliferation and migration of keratinocytes, also facilitates the final re-surfacing of the burn wound.  NOTE:  A silver-based dressing may be the only or the safest option for the care of a given patient.  In these cases, the final re-epithelialization may be delayed by a few days, but these dressings will not prevent the completion of this process.  Dressings shown to provide a non-adherent, protective coverage have been reviewed in the bandages and dressings module. 

Wound Cleansing

• must be extremely gentle to avoid traumatizing the new epithelium.  “Scrubbing” of a burn wound at this time is not indicated; a gentle rinsing and patting of the wound is sufficient. 
• Protection of the wound margins, including the new epidermis, will help keep dressings from adhering and avoid potential maceration. 

Dressing Selection and Techniques

• Dressing changes should only be undertaken every 3-5 days, depending on the dressing being used, unless there are concerns. 
• Dressing application should be discontinued when there is no drainage on the dressings and the wound area is visibly epithelialized. 
  • In many cases, the burn survivor may be hesitant to leave the area exposed.  At this point, education of the patient/care giver is important to care for the skin and to care for any wounds that may develop (blisters, skin tears, etc) as the new epidermis matures.

Clinical Pearl: how to handle adherent dressings to wound burn surfaces 

• do not force removal
• Trim any loose dressing and leave the adherent area intact. 
• Re-bandage the entire area and attempt removal at the next change. 
• If it is imperative that the dressing be removed, apply a thick layer of Vaseline or silver sulfadiazine and attempt removal in 24 hours.

Table 1. Dressing Options During Re-epithelialisation Phase

	Benefits	Risks
petrolatum-based gauze dressing (eg Xeroform or Vaseline gauze)	provides an occlusive layer that maintains a moist environment rarely adherent to wound surface
Non-adherent Foam dressing	rarely adherent to wound surface up to 7-days
Hydrocolloids	provides an occlusive layer that maintains a moist environment rarely adherent to wound surface	May maintain too moist wound environment
Transparent Films	Allows for visual monitoring of wound	Do not absorb drainage Blistering potential May maintain too moist wound environment Adhesive poses risk of wound or periwound trauma with removal
Alginate dressings	When allowed to attach to wound bed, will create an occlusive environment gelling of wound dressing maintains moist environment

Burn Wound Complication: Maceration

Maceration is one of the complications of burn wounds.  A small in vitro study in 2020 demonstrated that prolonged exposure to excessive moisture decreased the water-holding capacity of the stratum corneum, resulting in:

• Decreased elasticity and increased brittleness of the epidermis, risking skin rupture
• Decreased collagen density
• Flattening of the basement membrane.
• Decreased binding of the basement membrane to the extra-cellular matrix

All of these factors cause extremely weakened skin that is easily disrupted.  

A study in 2018 concluded that excessive maceration impairs re-epithelialization.  Other studies, not specific to burn wounds, show similar effects of maceration, including decreased physical and chemical integrity of the stratum corneum (causing decreased tensile strength and increased risk of infection) and softening of the skin (increasing the risk of skin breakdown).

Prevention is the best intervention to avoid the complications associated with maceration.  Selection of appropriate dressings to manage drainage is important.  If the bandages aren’t adequate to absorb the amount of drainage exuding from the burn wound, the wound will remain too wet.  Changing this dressing more frequently or selecting dressings with better absorptive capacity can help manage the drainage.  If occlusive dressings are being used, drainage can be trapped at the wound surface and cause maceration.  Increasing the frequency of dressing change or selecting a dressing with better moisture vapor transmission can assist with this.

Protecting the periwound skin and any epithelial islands within the wound can also minimize the risk of maceration or help the skin recover if maceration has occurred.  This can be accomplished by applying an ointment, paste (such as zinc oxide paste), emulsifier or liquid polymer to protect the skin from moisture exposure.  Applying an ointment (petrolatum or antibiotic ointment) or paste to the skin between toes (or fingers) will protect that skin.  

As mention in the Bandages and Dressings module, if the foot or hand is being bandaged as a “mitt,” and if the skin between the fingers or toes is spared, placing a dressing or dry gauze between the digits will decrease the occurrence of maceration significantly.  Protecting epithelial islands and spared skin in creases (eg flexor crease at the toes) will also help this skin remain healthy and contribute to the re-epithelialization process.

Zinc oxide paste is frequently used to protect periwound skin and the skin in web spaces.  

It is quite adherent to the skin and does not need to be completely removed at each dressing change.  The area can be gently wiped to remove the surface residue and crusted exudate.  If there is still adequate paste on the skin, it is not necessary to add more paste.  If there are areas of sparse coverage, more paste can be added.  When protection of the skin is no longer indicated, any resistant paste can be removed by applying a layer of petrolatum and wiping the skin after a few minutes.

Post-healing Skin Care

After the skin has re-epithelialized, care of the new epithelium must be diligent.  Moisture retention and hydration are key roles in the function of the stratum corneum and epidermis, and these functions are lost (at least temporarily) after a burn injury.  It can take up to 1 year after completion of re-epithelialization for these functions to be restored following superficial partial thickness burn injuries.  During this remodeling phase, hydrating creams or lotions can replace some of the moisture retention functions of the skin.  In a 2023 study, a positive benefit was found in using hydrating/moisturizing creams or lotions after re-epithelialization.  The positive benefits were found with both subjective and objective outcomes.  However, the study provided no results to support recommendations for any specific product.  General recommendations for moisturizing/hydrating skin include using a non-irritating cream or lotion specific for moisturization of the skin.  This includes ensuring that the product is fragrance-free, as the fragrance is usually alcohol-based which can cause irritation.  

Avoiding exposure to the ultraviolet rays of the sun is also an important factor in caring for the new epithelium.  There is minimal evidence specific to areas of burn injury, but there is abundant evidence regarding the negative affect of UV rays on uninjured skin, including increasing the risk of developing cancer.  This risk is potentially greater for the burn survivor as the healing epidermis is fragile and the developing melanocytes may be more susceptible to alterations by the UV rays.  Recommendations for protection from the sun include use of a sun screen of at least 50 SPF, as well as wearing clothing or a hat to cover the newly-healed skin.

Care of newly-epithelialized skin as it regains strength and function involve many more factors.  During bathing, aggressive scrubbing of the new skin while washing and drying should be avoided.  Application of moisturizers also needs to be done with minimal friction.  It is not necessary to completely rub the cream or lotion into the skin as it will be absorbed very quickly into the dry skin.  Selection of clothing also requires special attention.  The burn survivor should be advised to avoid any tight clothing, such as waist bands of skirts or pants if the burn injury involves the torso at the waist.  This tight narrow band can exert significant pressure and friction that can cause disruption of the skin.  Burn survivors should also be advised to avoid wearing any clothing made of rough fabric.  Recommendations typically include loose, soft clothing, and also includes attention to footwear if the burn injury included the foot.  Socks should always be worn with shoes to decrease the frictional forces as well.  

Activity and nutrition also require special attention.  A burn injury results in a persistent hyper-metabolic state for any extended period of time.  The larger the burn injury, the longer this state lasts.  During this time the burn survivor needs sufficient caloric intake to support metabolism, and consulting with a dietician or nutritionist would be helpful.  

Because of the energy requirements of this hypermetabolic state, the patient will also fatigue very quickly.  Education for energy conservation and therapy to facilitate regaining endurance and strength will improve outcomes.  

Post-burn Rehabilitation

Rehabilitation is an integral part of burn injury recovery.  A newer area of assessment and treatment of burn injuries is the determination of involved Cutaneous Functional Units (CFUs).  These are defined as fields of skin associated with motion of adjacent joints.  For example, 29 distinct CFU’s have been identified in the palm of the hand.  Prior to identification of CFU’s, the concern of the functional impact of scars involved scars crossing the joint.  It is now recognized that joint motion relies on the elasticity of skin around the joint as well.  Determining the involvement of CFU’s in a burn injury has also been found to be predictive of the risk of contracture development.  As previously stated, the remodeling phase can take up to 2 years to fully mature.  During that time, ROM and functional activities can affect the long-term outcome of the burn survivor.  

A study in 2023 found that initiating gait training on a treadmill for patients with lower-limb burn injuries improves gait outcomes compared to over-ground gait training.  Eventually, over-ground ambulation is an important intervention.  But according to this study, starting on a treadmill provides a significant benefit.

Burn Scar Management

Hypertrophic scar formation is a significant debilitating factor following a burn injury.  For burn survivors who suffer deep-partial or full thickness injuries, development of hypertrophic scars is inevitable.  Damaged or destroyed extracellular matrix is unable to regenerate, and therefore can’t provide the components needed to regenerate the epithelium.  The excessive and prolonged inflammatory response that is normal to burn injuries results in the production of immature collagen.  Additionally, because the epidermis is not regenerated, the normal functions of the skin are not restored.  There is a loss of sweat glands, which diminishes thermoregulation in that area.  Sebaceous glands are not available to provide lubrication to the skin and hair follicles.  Pliability/elasticity of the skin and soft tissue is severely diminished as the fibroblasts convert to myofibroblasts which directly contributes to scar contracture.  

Hypertrophic scars are also aesthetically unappealing  

Hypertrophic scars are thick and very stiff.  Coverage with a skin graft can mitigate some of the complications of hypertrophic scars.  This wrist burn would have benefitted from a skin graft, but was allowed to heal secondarily.  The hypertrophic scar across the dorsal wrist may prevent functional wrist flexion as it matures.

This upper extremity burn crosses the lateral elbow.  Although it doesn’t cross the anterior aspect of the elbow, the potential for decreased elbow flexion and extension exists.

When the scar is put on a stretch, as with elbow extension in this case, there is visible blanching.  This indicates that there is still vascular activity in the scar; the remodeling phase is still active.  Scar management interventions can affect the long-term outcome of this scar.

If after maturation there are functional limitations or aesthetic concerns, surgery can be considered.  Scar contracture release, debulking or other cosmetic surgery may have a role in improving scar outcomes.

There is abundant research and case reports studying various interventions intended to improve outcomes related to hypertrophic scars.  Unfortunately the outcomes of these studies and reports are widely variable.

A 2023 report determined that there is no consensus for any single intervention in management of hypertrophic scars.  It did find limited support for the use of silicone.  There was also a Cochrane review in 2021 showing limited RCT’s demonstrating the benefits of silicone gel sheets for hypertrophic scarring.  In spite of the lack of strong evidence, many algorithms and protocols developed by burn teams include silicone as the first or primary therapy in scar management.

Massage therapy was found in recent studies to provide significant short-term improvement on burn scars, but no long-term benefit was appreciated.  Massage was also found (in a 2017 report) to decrease pruritis, but no evidence was found on lasting effect on scar height or thickness with massage.

Some studies on scar management were specific to hands, first stating that prevention is the best intervention for positive outcomes.  It determined that early initiation of compression to decrease edema, aggressive ROM with stretching, and the use of splints were effective in improving outcomes for burn survivors with hand burns.  It also reported that any joints that started developing contractures benefitted from use of K-wires.

Pressure garment therapy (PGT) has been extensively studied for management of burn scars.  An animal study in 2015 reported that effectiveness of PGT is directly related to the anatomical location of the scar.  It also found that contractile strength and scar contracture was significantly improved with PGT versus scars not treated with PGT.  Although the mechanism of action of pressure garments is not fully understood, it is theorized that the mechanical forces applied by the pressure garments decreases the scar contracture and helps to organize the deposition of collagen during the remodeling phase.  

Multiple studies are contradictory or provide inconsistent results.  Some show evidence of positive outcomes with PGT when the garments are worn 24/7 (being removed only for bathing) versus when the garments are worn for less time.  Some reports show the ideal pressure exerted by garments is 15-25 mmHg, although pressure under garments is not routinely measured.  Other studies recommend a pressure that equals or exceeds capillary closing pressure, which can be 40 mmHg in some areas.  There are consistent reports that garment fatigue significantly decreases the effectiveness of PGT.  In all studies involving human subjects, outcomes are directly affected by poor patient adherence.  Reasons reported for poor adherence include

• Garments are uncomfortable
• Garments can be too hot
• They are difficult to don and doff
• Cost is a significant deterrent to obtaining garments, as well as in replacement garments when garment fatigue becomes a factor

Effectiveness of PGT on burn scars is not well supported in some cases.  Some studies report significant improvement in scars with PGT using a pressure of 15-25 mmHg, but the studies included in this report had a weak level of evidence with no studies looking at long-term results following PGT.  Yet another report demonstrated good evidence in both prophylactic and curative interventions with PGT.  If the PGT is initiated within 2 months of injury, with a pressure of 20-25 mmHg for at least 12 months, there was improvement in scar color, thickness, pain reduction and scar quality (as assessed with a validated scar assessment scale).

Other interventions in management of burn hypertrophic scars have also been investigated.  In 2023, a study looking at use of corticoid-embedded dissolving microneedles was studied.  It found an effective delivery method in using a hyaluronic acid dressing onto which the microneedles are implanted.  After applying this dressing to a burn scar, the microneedles penetrate the epidermis with minimal to no pain and can travel into the dermis.  As the microneedles dissolve, they release the embedded corticosteroid, which has been found to be effective in reducing the thickness of hypertrophic scars.  This intervention holds great promise as being superior to intralesional steroid injections, which can be extremely painful and have a limited area of effectiveness.

Serial casting has also been studied.  A small study in 2023 found recovery of full ROM could be achieved with as little as 1 cast change.  This study included different frequency of cast changes (1, 3 and 5 times per week), but the ultimate outcome was full ROM with serial casting.  This protocol included therapeutic interventions to the joint at each cast change:

• Moist heat
• AROM with end-range stretching
• Joint glides
• Progressive resistive exercises

Once full ROM is achieved, a night-time splint was used to maintain ROM.

In 2022, a study was undertaken comparing Silicone, intra-lesional injections and laser therapy.  It found that all were effective in the treatment of burn scars when assessing the scars using the Vancouver Scar Scale.  It found that silicone used in combination with intra-lesional injection was superior to either intervention alone.  It also reported significant efficacy in using topical silicone in the treatment of hypertrophic burn scars.

Pruritis

Pruritis, or itching, is a significant complication of burn injuries.  It is first important to determine if there are underlying factors that may be contributing to the itching.  It may be related to an allergy or sensitivity to drug therapy – either topical or systemic.  The burn survivor may have an underlying dermatological disorder, or may be developing a neuropathy.  If any of these factors are identified, treatment can be targeted to reduce pruritis.

However, if pruritis is directly related to the burn injury, the mechanism for this is not well understood.  Therefore, successful treatment has been difficult to discover and no consensus has been reached supporting any single intervention or combination of interventions, and no consistent algorithms have been found to support a given intervention.

Treatments reported to show some success include:

• Topical treatment with creams, lotions or emollients to restore the barrier function
• Systemic treatments, some with moderate results
  • Antihistamines
  • Gabapentin
  • Gabapentin in combination with Pregabalin
    • This combination was found superior to either used singly
• Antidepressents
  • Somewhat effective for patients with pruritis who also suffer from depression or anxiety
• Extracorporeal Shock Wave Therapy

• Physical treatment: found to be effective during the course of therapy, but no long-term benefits were noted
  • Compression
  • Massage

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