Does Enzymatic Debridement Allow Us To Perform Conservative Treatment On Clinically Deep Hand Burns? A Retrospective Review

Summary

The hands are one of the main locations of burns. In deep second-degree and third-degree burns, the gold standard of treatment is surgical debridement and subsequent coverage, which can result in suboptimal aesthetic and functional results. The aim of our study is to assess whether treatment by initial enzymatic debridement (NexoBrid®) of deep second-degree and third-degree burns prevents the need for surgery. We carried out a retrospective study of 53 hands with deep burns treated in our centre from May 2015 to December 2016. Two experts evaluated the initial photographs of the burns and classified them as surgical or nonsurgical (interobserver kappa index = 0.83). These assessments were compared with the actual need for surgery on each hand. Sixteen of the 32 (50%) hands that the experts considered surgical spontaneously epithelialized. Four of the 17 hands (23.5%) that were not considered surgical required a split-thickness skin graft for healing. Enzymatic debridement helps to preserve viable tissue, which reduces the number and extension of surgical interventions, thus favouring better results.

Introduction

Burns are a significant reason for emergency care, hospital admission and even surgical intervention.¹ A high percentage of burns occurs on the hands.² Identifying the burn depth is very important since depth will determine the type of therapeutic approach. Epidermal and superficial dermal burns will heal spontaneously, while deep dermal and full-thickness burns require surgery. ³ For deep dermal and full-thickness burns, tangential surgical debridement followed by coverage with skin autografts in the first five days after the injury is considered the current standard of care.⁴

Due to their anatomy and physiology, surgical debridement of the hands is a technically complex procedure that may result in complications and suboptimal functional and aesthetic results.^5,6 In recent years, several articles on enzymatic debridement with NexoBrid (MediWound Ltd., Israel) as a therapeutic alternative to surgery have been published, demonstrating its safety, efficacy and benefits for patients, even avoiding the need for surgery.^2,7,8 NexoBrid enzymatic debridement solution mixes proteolytic proteins derived from bromelain with specific high enzymatic activity. The immediate post-debridement results allow differentiation of skin structure characteristics and the exposed vascular patterns, facilitating a more accurate diagnosis of the burn’s depth and determining definitive treatment.⁸

The objective of this study is to assess the proportion of clinical hand burns requiring surgery for which surgery was no longer necessary after enzymatic debridement.

Materials and methods

We performed a descriptive retrospective study of all patients older than 18 years who underwent enzymatic debridement after sustaining burns affecting the hands between May 2015 and December 2016, in the Burn Unit of the Vall d’Hebron University Hospital (Barcelona, Spain). The Burn Unit of the Vall d’Hebron University Hospital in Barcelona is the reference center for Catalonia, the Balearics and Andorra, with a catchment population of approximately 8 million people. In the last year, approximately 1500 burn emergencies have been treated, with approximately 550 admissions to the burn center. The present study has been approved by the Ethics and Clinical Research Committee of our center (DAR-BRO-2017-01).

Enzymatic debridement was performed according to the protocol of our center and the manufacturer’s indications, within the first 3 or 4 days of the injury. According to our internal protocol, only intermediate second-degree burns or deeper are candidates for enzymatic debridement. Pain control was carried out with sedoanalgesia or regional nerve block of the affected limb. Before NexoBrid application, blister removal and mechanical cleaning of the burns were performed. Once the devitalized epidermal layer of the skin was removed, a moist dressing with antiseptic solution was applied for at least two hours. Next, the dressing was removed, the area to be treated was surrounded with sterile petrolatum, and a 1.5 to 3 mm layer of NexoBrid was evenly applied. Then, an occlusive dressing was put on. Four hours later, the dressing was removed, and the product was cleaned with physiological saline and scraped with a spatula.

As a variation of the application protocol proposed by the manufacturer, a moist dressing with a disinfectant solution (Prontosanâ, B. Braun, Germany) is placed until the next morning, which helps us eliminate any remaining product. This procedure has been carried out by other groups.⁹ Once this procedure is completed, based on the characteristics of the wound bed, we determine whether conservative treatment is appropriate (waiting for spontaneous epithelialization of the wound), or if surgical intervention is necessary, covering the wound with split-thickness skin autografts depending on the decision.⁸ If conservative treatment is chosen, we cover the wound bed with Suprathel® (PolyMedics Innovations GmbH, Filderstadt, Germany) and Urgotul (Laboratoires URGO, Dijon, France). The burn is evaluated every 5 days until wound healing. If skin graft is needed, it is scheduled 3-5 days after initial debridement, and the dressing is performed with Mepitel (Mölnlycke Health Care, Gothenburg, Sweden) and nitorfurazone ointment 0.2%.

Data collected included age, sex, the laterality of the affected hand, the etiology of the burn, the number of days until enzymatic debridement was performed, the time elapsed until healing and any incidents that occurred during the treatment.

For all patients, photographs of their hands were taken at the time of emergency care. These photographs were evaluated in parallel by two plastic surgeons specialized in burns who were not involved with the usual healthcare team and were unaware of the cases. Considering the etiology, total body surface area affected, age and sex of the patient and the initial clinical appearance based on photography, these two experts classified the burns as surgical or nonsurgical.

We compared the experts’ predictions with the actual treatment implemented. To analyze the agreement between the experts, the interobserver kappa correlation test was used.

Results

males and 5 females. Twenty of these patients presented burns on both hands and 13 had unilateral burns, resulting in a total of 53 hands evaluated. The average age was 47.7 years (range 18-94 years). The main burn etiology was flame (40 hands, 75.4%), followed by electrical flash (9 hands, 16.9%), scalds (3 hands, 5.6%) and finally, one case of dermabrasion (1.8%) (Table I).

Table I. Demographic data, etiology of burns, surgical treatment and interobserver assessment of patients treated with NexoBrid.

Enzymatic debridement was performed on day 1.9 post-burn (range 1-4 days), with debridement duration of 4 hours in all patients. Enzymatic debridement was effective in 100% of the cases. The average time to complete healing was 27.4 days (range 11-86 days). Patients who did not undergo surgery healed in 24.9 days (range 14-72 days), whereas patients requiring surgical intervention healed in 31.3 days (range 11-86 days). The initial photographs of the cases were evaluated by a panel of two plastic surgeons that were experts in burns and were not involved with the care of these patients. Their evaluations coincided for 49 of the 53 hands, classifying 32 hands as surgical and 17 as nonsurgical (kappa index 0.83, standard error 0.1). Sixteen of the 32 (50%) hands for which the experts agreed surgery was indicated ultimately underwent surgical treatment (Fig. 1), and the other 16 hand wounds (50%) epithelialized spontaneously (Fig. 2). For four of the 17 (23.5%) hands that were considered nonsurgical, the evolution of the burns was not favorable and split-thickness skin grafts were required for healing. As for the hands that the experts did not agree on, two of the hands spontaneously epithelialized and the other two required surgical intervention (Table II).

Fig. 1. Images of a patient with deep abrasions on the left hand (A) treated with enzymatic debridement (B) and a heterodigital flap (C). Skin autografts were unnecessary and healing was spontaneous at 15 days. Image (D) shows the outcome at the 3-month check-up.

Fig. 2. Images of a patient with clinically deep burns on both hands (A) treated with enzymatic debridement (B). Both hands spontaneously epithelialized in 20 days. Results after two years of follow up (C).

Table II. Expert consensus results.

Discussion

Enzymatic debridement of burns with NexoBrid has shown favorable results in several studies published in recent years.^2,7,9-14 In our case series, debridement with NexoBrid was effective in 100% of the cases. In our opinion, this type of debridement is superior to tangential debridement, especially in anatomical areas with thin skin and narrow and angled contours, such as the hands.¹⁰ In such regions, the possibility of maintaining the maximum viable dermis possible after debridement increases the likelihood of spontaneous epithelialization and better esthetic outcomes.¹⁰

In our retrospective review, all the hands that were treated with enzymatic debridement had clinical characteristics of intermediate second-degree burns or deeper according to the assessments of the plastic surgeons of the Burn Unit. Therefore, all these hands would have had a high likelihood of undergoing surgical debridement and skin autografting if classic treatment had been carried out: any burn that is not expected to be cured in less than 3 weeks is subject to this procedure.¹⁵

Enzymatic debridement decreased the number of surgical procedures expected, as only 22 out of the 53 hands evaluated (39.3%) were surgically treated. Overall, 50% of the hands that were classified as deep and potentially surgical by the burn experts epithelialized spontaneously. After debridement with NexoBrid®, these wounds did not show the same depth that was initially expected. This difficulty in establishing burn depth through expert clinical review has already been reported by other authors, as reflected by an estimated success rate of approximately 60%.¹⁶ The appearance of the post-debridement bed allows us to better gauge the depth of a burn.⁸

The average healing time for the hands that spontaneously epithelialized after enzymatic debridement in our series was 24.9 days, while it was 31.3 days for those requiring surgery. The hands that were grafted took more time to heal than expected, as Integraâ (Dermal Regeneration Template, Ethicon, Inc., Somerville, NJ, USA) was used to improve scar quality. ^17,18 Furthermore, in some cases revision surgeries were required, as has been reported to happen during the learning curve for burns debrided with Nexo-Brid.⁹ The results of spontaneous healing observed in our study do not differ from those reported by other authors in studies in the same field.^2,9,10,12 Classically, if healing of a burn exceeds 3 weeks, an increased risk of pathological scarring exists.¹⁹ With NexoBrid enzymatic debridement, in our series of patients the total time to spontaneous healing in most cases was greater than this interval, which has also been published by other groups.^2,9,10,12 However, some authors have suggested that despite requiring a longer healing time, the use of NexoBrid allows removal of the inflammatory component early; therefore, the quality of scarring is not affected.^10,12

Four of the 17 patients who had burns that were not clinically deep according to the experts ultimately required surgery. Evidently, this may be related to an incorrect clinical assessment by our experts. However, other factors can interfere with the evolution of burns after enzymatic debridement, similar to the evolution of any burn, such as drying of wounds, poor peripheral perfusion due to patient instability, infection, edema or lack of rest.²¹

Some studies argue that treatment by enzymatic debridement is also capable of decreasing the number of escharotomies due to compartment syndrome.^10,12 In our study, none of the patients who underwent enzymatic debridement required escharotomies to avoid compartment syndrome.

Limitations

The present study has the inherent limitations of a retrospective observational study based on a database. The surgeons who evaluated and classified the burns used photographs rather than directly assess the patients. However, all the photographs that were evaluated were hands with intermediate second-degree burns or third degree, which were, therefore, potentially surgical. We acknowledge that our study is limited because there is no standardly treated control group. It would have allowed us to perform a comparative study, not just a descriptive one. Since 2015, enzymatic debridement is performed on all the deep - Fig. 1 - Images of a patient with deep abrasions on the left hand (A) treated with enzymatic debridement (B) and a heterodigital flap (C). Skin autografts were unnecessary and healing was spontaneous at 15 days. Image (D) shows the outcome at the 3-month check-up Fig. 2 - Images of a patient with clinically deep burns on both hands (A) treated with enzymatic debridement (B). Both hands spontaneously epithelialized in 20 days. Results after two years of follow up (C) Table II - Expert consensus results burned hands in our center, so the number of patients treated with the standard of care is very small. Finally, the aim of the current study was to assess the burns that did not require surgery after enzymatic debridement. Nonetheless, long-term follow up would be preferable to evaluate functional and scar results.

Conclusion

Enzymatic debridement effectively removes devitalized tissue from burns by preserving viable tissue and helps us diagnose deep burns by exposing unaffected skin structures and vascular patterns. Our study suggests that, as a result of this enzymatic debridement, the surgeon has more information to more accurately estimate the depth of a hand burn and can therefore select conservative treatment, decreasing the number of surgical interventions. In our study, 50% of hand burns clinically classified as deep, and therefore as surgical, did not require surgery after enzymatic debridement. However, we believe that highquality prospective clinical studies are necessary to compare enzymatic debridement with the current standard treatment, and assess the effectiveness of debridement, the need for surgery, long-term scar quality and the healing time of such wounds.