Introduction: Chemical necrectomy of deep burns using 40% benzoic acid has been used extensively by the Department of Burns and Reconstructive Surgery at the University Hospital since its establishment in 1982. In spite of definite advantages for the patient and medical staff, hard data concerning benzoic acid absorption through skin necrosis and patient safety was missing.
Material and methods: We examined 22 burn patients in collaboration with the University Hospital Brno, Department of Clinical Biochemistry. The plasmatic levels of benzoic acid, hippuric acids and glycine, which is consumed during the metabolism of benzoic acid, were measured. Urine samples were collected to determine the total amount of hippuric acid that is excreted. We were able to determine the total amount of absorbed and excreted benzoic acid from these values.
Results: We consistently found that there was a rapid and short-term increase of plasmatic levels of benzoic acid (maximum 1.3 mmol/l). This value is about 5 times lower than the minimum toxic level of this acid (6.5 mmol/l). The same course has been observed in hippuric acid. The level of glycine dropped slightly, but was still within the normal range.
Discussion: Typical and atypical courses of the levels of both acids were discussed as well as the correlation of the dynamics of elimination with the extent of benzoic acid application in relationship with the clinical status of the patient. The effectiveness and safety of this method was evaluated.
Conclusion: After summarizing the observations, it was demonstrated that chemical necrectomy using 40% benzoic acid is a selective method comparable with other types of sharp necrectomy. Chemical necrectomy is inexpensive, easy to perform and also reduces blood loss. Toxicity of absorbed benzoic acid is clinically negligible. Furthermore, benzoic acids antimycotic and antibacterial properties prevent the development of wound infection.
Keywords: Burn wound; benzoic acid; chemical necrectomy; glycine toxicity.; hippuric acid; necrectomy; selectivity; skin necrosis.