Trichloroacetic acid (80%) as a chemical debridement method for chronic venous leg ulcers—A pilot study

Abstract

Debridement is essential for the optimal care of venous leg ulcers. Several debridement methods with different limitations may be deployed. Trichloroacetic acid (TCA) is used for several dermatological purposes. Its application as a chemical debridement method for leg ulcers has never been explored. We designed a prospective study to determine the role of 80% TCA solution as a chemical debridement method for leg ulcers, regarding efficacy and procedure‐associated pain. Chronic venous leg ulcers were treated with 3 cycles of 80% TCA solution or curettage over 1 week. Pain and the mean percentage of fibrin and devitalized tissue covering wound bed were evaluated. At the end of the study, a trend towards larger fibrin mean reduction among the TCA treated ulcers was observed, although this difference was not statistically significant (P = .35). The mean pain score after TCA application was significantly reduced compared to pain after curettage alone (P < 0.001). TCA presented several advantages over mechanical debridement: it is a more selective debridement method, has haemostatic properties, and a simpler and faster application. The 80% TCA solution may be a cheap, simple, and considerably less‐painful chemical debridement method for venous leg ulcers compared to classical mechanical debridement.

1. INTRODUCTION

In chronic wounds the presence of fibrin, devitalized tissues, bacteria, and other wound debris is associated with refractory ulcers.1 Routine debridement is essential for the optimal care of venous leg ulcer (VLU), improving the healing time.2, 3 Several debridement methods are available and pain is one of their most significant drawbacks. Debridement methods may be deployed as a single therapeutic modality, although their combination seems ideal to optimise efficacy with minimal limitations including pain.2

Trichloroacetic acid (TCA) is an acidic solution used in different concentrations for several purposes in dermatological clinical practice. Its use as a chemical debridement method for VLU has not been previously explored.

We aimed to determine the potential role of 80% TCA solution as a chemical debridement method for chronic VLU, regarding efficacy and procedure‐associated pain.

2. MATERIALS AND METHODS

We performed a prospective, non‐randomised clinical study for 1 month in our dermatology department. Adult patients with chronic non‐infected, non‐complicated VLU were included. All ulcers were divided with a skin marker. In half of the VLU, 80% TCA was applied with a cotton swab over the devitalized tissues (until frosting occurred) followed by curettage 5 minutes later. The other half received an exclusive mechanical debridement. Pain was evaluated using Visual Analog Pain Scale after TCA use and after curettage. Subsequently, activated charcoal dressings with silver were used and compression therapy was applied. Three sequential cycles of 80% TCA were performed at 0, 48, and 96 hours. One week later, the 2 ulcer halves were compared (Figures 1 and 2).

Figure 1.

Evolution of an ulcer included in the study. At day 1, the lower half was treated with the 80% TCA solution until frosting of the wound bed occurred; the upper half received solely a mechanical debridement with a 7‐blade curette. At day 7, the lower ulcer half presented a significantly higher reduction in the mean percentage of fibrin and devitalized tissues (%FDT) covering wound bed

Figure 2.

Evolution of an ulcer showing a remarkable difference in the wound bed fibrin content, that is significantly reduced in the lower ulcer half, treated with the 80% TCA solution, compared to the mechanically debrided upper half

The difference between the mean percentage of fibrin and devitalized tissue (%FDT) covering wound bed of the TCA‐treated and the mechanically debrided ulcer half was considered the primary endpoint. The difference in the mean pain score after TCA application and after curettage was defined as the secondary outcome.

Data were analysed with SPSS Software 22.0, IBM Corp (Armonk, New York) and compared using Mann‐Whitney test. P‐values <.05 were considered statistically significant.

All patients provided written informed consent. The study was conducted according to the Helsinki Declaration and was approved by the Institution's Ethical Committee.

3. RESULTS

Sixteen VLU ulcers confirmed by Doppler ultrasound of 9 different patients were included. The mean age of the patients was 78.3 years. Ulcer area varied from 4 to 36 cm² and the mean ulcer duration ranged from 2 to 96 months (mean = 28.4). Nine were located in the medial and 7 in the lateral malleoli.

At the beginning of the treatment, the mean %FDT covering wound bed was 84.7% and 88.1% for the TCA‐treated and the exclusively mechanically debrided ulcer half, respectively. At the end of the study, we observed a mean reduction of 25.3% in the %FDT for the TCA‐treated and 18.1% for the other half. Although this difference was not statistically significant (P = .35), there was a trend towards a larger fibrin mean reduction when TCA was combined with curettage. Additionally, patients reported a mean pain score of 3.48 after chemical debridement with TCA compared to 7.27 after curettage alone, which was statistically significant (P < .001). Local or systemic adverse events were not reported.

4. DISCUSSION

TCA is used for several treatment purposes in dermatology practice including actinic damage, warts, acne scars, and cosmetic peels.4, 5 Several mechanisms of action underlying these applications have been proposed. TCA is toxic to keratinocytes and fibroblasts by inhibiting their proliferation and protein synthesis,6 while promoting protein precipitation and denaturation.7 By contrast, TCA downregulates metalloproteinases and upregulates TGF‐β and PDGF‐β expression promoting epidermal renovation.8 It seems possible that TCA toxicity to cells and proteins could contribute to the removal of debris and devitalized tissues while simultaneously promoting proliferation and remodelling of wounds by increasing the production of growth factors. Theoretically these actions may explain TCA debridement potential and may culminate in decreased healing times, but the latter possibility was not assessed in our study.

During our study, we observed several unexpected advantages of TCA application over mechanical debridement techniques. In fact, haemorrhage is rare because of TCA haemostatic properties. Furthermore, it is a more selective method because fibrin and devitalized tissues acquire frosting faster than viable tissues. Besides, because fibrin is easily removed by curettage after frosting, we found TCA particularly useful for ulcers with adherent and poorly detachable fibrin where mechanical techniques may be painful and of limited efficacy.

Furthermore, TCA application is easier and faster compared to mechanical debridement, which may contribute to a shorter and weaker stimulation of free nerve endings in the wound bed explaining the limited pain associated with the procedure.

We recognise the limitations of our small sample‐sized study. Additionally, healing times were not assessed and TCA was not evaluated alone but only in combination with curettage. Finally, as objective measures to evaluate debridement efficacy are not available, we decided to use the mean %FDT covering wound bed as a parameter to more accurately define debridement efficacy.

Despite these limitations, we believe 80% TCA solution should be further explored as a cheap, simple chemical debridement method for VLU associated with considerably less pain than classical mechanical debridement.

Pinheiro RR, Duarte B, Cabete J. Trichloroacetic acid (80%) as a chemical debridement method for chronic venous leg ulcers—A pilot study. Int Wound J. 2018;15:438–440. 10.1111/iwj.12884