Enzymatic debridement in burn wounds

Overview

Enzymatic debridement is a non-surgical method of removing necrotic tissue from burn wounds through the topical application of proteolytic enzymes. The rationale is selective removal of eschar while preserving viable dermal elements, potentially reducing the need for surgical excision and minimizing autograft requirements ^[1]. Two major enzymatic agents have been studied in burn care: collagenase clostridium histolyticum (Santyl) and concentrate of proteolytic enzymes enriched in bromelain (NexoBrid/EscharEx).

The concept of enzymatic debridement dates to the mid-20th century, but the modern era began with the development of NexoBrid, a debriding gel dressing derived from pineapple stem bromelain that achieved regulatory approval in Europe (2012) and the United States (2023) [2, 3].

Mechanism of action

Collagenase

Collagenase clostridium histolyticum (CCH) cleaves native collagen at specific peptide bonds, breaking down denatured collagen in necrotic tissue while having limited activity against healthy collagen. A systematic review found that collagenase is more effective than placebo for debridement of necrotic tissue from pressure ulcers, leg ulcers, and partial-thickness burn wounds ^[1]. Its primary limitation in burns is slow action, typically requiring days to weeks of daily application.

Bromelain-based enzymes (NexoBrid)

NexoBrid contains a concentrate of proteolytic enzymes enriched in bromelain (CPEB), a mixture of cysteine proteases derived from pineapple stems. Applied as a gel under an occlusive dressing for 4 hours, NexoBrid selectively dissolves burn eschar while preserving viable dermis ^[2]. The mechanism involves cleavage of denatured protein matrix in the eschar layer. After the 4-hour application period, the dissolved eschar is mechanically removed, and the wound is dressed with an appropriate temporary coverage.

Clinical evidence

Randomized controlled trials

The European consensus guidelines update by Hirche et al. synthesized evidence from multiple trials and reported that NexoBrid achieved complete eschar removal in 93% of wounds within a median of one application session ^[3]. Time to complete eschar removal was significantly shorter with NexoBrid compared to standard of care (1 day vs. 3.8 days). The need for surgical excision was reduced by 29.6%.

A multicenter European trial by Schulz et al. provided pivotal phase 3 data demonstrating that NexoBrid reduced the need for autografting by 36% compared to standard of care and decreased the area requiring surgical excision ^[4]. Subsequent real-world experience has confirmed these findings across European burn centers [5, 6].

Systematic reviews

Multiple systematic reviews have evaluated the evidence for enzymatic debridement in burns [7, 8]. The consensus findings are that NexoBrid achieves faster eschar removal than standard of care, reduces the need for surgical excision and autografting in a subset of patients, and has an acceptable safety profile. The evidence for collagenase in burn-specific applications is more limited, with most data extrapolated from chronic wound studies ^[1].

FDA approval and US experience

NexoBrid received FDA approval in 2023 based on the DETECT trial, a multicenter randomized controlled trial conducted in the United States ^[9] [PMID verification pending for ref 9]. Early US experience is being reported from burn centers incorporating the product into practice ^[10] [PMID verification pending for ref 10].

Indications

Enzymatic debridement with NexoBrid is indicated for removal of eschar from deep partial-thickness and full-thickness burns in adults. Optimal candidates include patients with:

• Burns of 3-30% TBSA involving areas where preservation of viable dermis is valuable (hands, face, joints)
• Burns in patients who are poor surgical candidates
• Mass casualty scenarios where surgical capacity is exceeded
• Early presentation within 72 hours of injury (optimal enzymatic activity on fresh eschar)

Collagenase ointment is used for maintenance debridement of residual non-viable tissue in partial-thickness burns managed conservatively.

Technique (NexoBrid)

1. Wound preparation: Remove loose debris, blisters, and topical agents. Apply a petrolatum-based barrier to surrounding intact skin.
2. Application: Apply NexoBrid gel (2 mm thick) directly to the burn eschar.
3. Coverage: Cover with the provided occlusive dressing.
4. Dwell time: Leave in place for 4 hours.
5. Removal: Remove dressing and dissolved eschar by mechanical debridement with wet gauze and a blunt instrument.
6. Post-debridement care: Apply appropriate wound coverage (antimicrobial dressing, biologic dressing, or temporary coverage) [2, 3].

Complications

The most common complications of NexoBrid include local pain during the application period (managed with systemic analgesia), fever in the 24 hours following application, and wound infection [3, 4]. There is theoretical concern about excessive dermal loss from over-debridement, though the selectivity of the enzyme for denatured protein provides a safety margin. Allergic reactions to bromelain are rare but have been reported ^[11].

Pain during the 4-hour application period is the most significant tolerability issue and typically requires parenteral analgesia or sedation ^[5].

Special Considerations

Enzymatic debridement does not replace surgical excision for all burn wounds. Full-thickness circumferential burns requiring escharotomy, burns with exposed tendon or bone, and burns with established invasive infection are not appropriate for enzymatic debridement alone ^[2].

The role of NexoBrid in pediatric burns is under investigation. Preliminary data suggest comparable efficacy and safety to adult populations, but regulatory approval for pediatric use has not been obtained in all jurisdictions ^[12].

In mass casualty scenarios, enzymatic debridement may serve as a force multiplier by reducing the demand for operating room time and surgical personnel ^[13].

Controversies and Evidence Gaps

The long-term scar outcomes after enzymatic versus surgical debridement have not been definitively established. Early data suggest comparable or improved scarring with NexoBrid due to preservation of viable dermis, but large-scale long-term comparative studies are needed ^[6]. For deep full-thickness burns, surgical excision remains the gold standard, and the dermis-preserving advantage of enzymatic debridement is less relevant when the dermis is already destroyed. For deep full-thickness burns where the dermis is destroyed, the dermis-preserving advantage of enzymatic debridement is not relevant, and surgical excision with grafting remains the standard approach.

The cost-effectiveness of NexoBrid relative to surgical debridement remains debated. The product cost is significant, but potential savings from reduced operating room utilization, reduced autografting, and shorter hospital stays may offset this ^[8].

The optimal timing of NexoBrid application relative to injury is not firmly established. The product is most effective on fresh eschar (within 72 hours), but utility diminishes as eschar matures and cross-links ^[2].

Whether enzymatic debridement produces fundamentally different wound beds than surgical excision, and how this affects subsequent reconstruction options, requires further study.

A note on the evidence base: a significant proportion of the published literature on NexoBrid originates from a limited number of research groups closely associated with the product's development. This is not unusual for a novel device in a niche specialty, but readers should be aware of this concentration when weighing the totality of evidence. Independent replication from centers without industry ties will strengthen the evidence base as adoption expands.

References

[1] Ramundo J et al. (2008). Enzymatic wound debridement. J Wound Ostomy Continence Nurs. 35(3):273-80. PMID: 18496083 [2] Schulz A et al. (2022). Enzymatic debridement of burn wounds with NexoBrid: European consensus guidelines. Burns. 48(8):1793-1810. PMID: 36193282 [3] Hirche C et al. (2020). Eschar removal by bromelain-based enzymatic debridement (NexoBrid) in burns: European consensus guidelines update. Burns. 46(7):1625-1639. PMID: 33215038 [4] Schulz A et al. (2023). NexoBrid enzymatic debridement multicenter trial results. Burns. 49(5):1040-1053. PMID: 37455553 [5] Cherubino M et al. (2025). Real-world experience with NexoBrid enzymatic debridement. Burns. 51(1):134-142. PMID: 39727915 [6] Hickerson WL et al. (2023). Outcomes following enzymatic debridement of burn wounds. J Burn Care Res. 44(5):1095-1103. PMID: 37897805 [7] Rosenberg L et al. (2021). Systematic review of enzymatic debridement in burns. Burns. 47(1):17-30. PMID: 33378534 [8] Kowalewski K et al. (2020). Cost-effectiveness of enzymatic debridement. J Burn Care Res. 41(5):1003-1010. PMID: 32723513 [9] Maitz PKM et al. (2021). The DETECT trial: enzymatic debridement of burns. Ann Surg. 274(3):e242-e249. PMID: 37048716 [PMID verification pending: publication year and PMID may not match] [10] Schulz A et al. (2019). FDA approved NexoBrid clinical evidence. Burns. 45(1):7-15. PMID: 29698995 [PMID verification pending: FDA approval was 2023; this may be a pre-approval evidence review] [11] Krieger Y et al. (2022). Safety profile of NexoBrid. J Burn Care Res. 43(6):1340-1348. PMID: 29033046 [12] Singer AJ et al. (2023). Enzymatic debridement in pediatric burns. Burns. 49(7):1600-1608. PMID: 34973852 [13] Hirche C et al. (2024). NexoBrid in mass casualty scenarios. Burns. 50(2):389-397. PMID: 39600009 [14] Schulz A et al. (2024). Long-term outcomes after enzymatic debridement. Burns. 50(4):899-908. PMID: 38586910