A rare case of chemical burns caused by a mixture of sulphuric acid and hydrofluoric acid

To the Editor

A mixed acid solution spilled on the pants of a 40-year-old man weighing 85 kg from a broken transmission pipe in the workplace. After removing the contaminated clothes and copious lavage for 20 mins on-site, the patient was immediately sent to the emergency department 1 h post-exposure. On admission, the patient, complained of severe pain over the injury sites, and stated that the hazardous solution was concentrated sulphuric acid. Physical examination revealed burn sites distributed mainly on the lower extremities with definite boundaries (Fig. 1). His previous health status was good without prior diseases. By 1.5 h post-burn, patchy erythema appeared on the surrounding normal skin (Fig. 1B). Laboratory results showed hypocalcaemia (1.34 mmol/L; normal range: 2.25–2.75 mmol/L), elevated white blood cells (11.4 × 10⁹/L; normal range: 4–10 × 10⁹/L), slight acidosis (pH: 7.30), and normal serum potassium and magnesium levels. The urinary fluoride level was 35 (normal: ∼1.7) mg/L. Chest X-ray and electrocardiography indicated no abnormalities. The technical staff in the factory confirmed that the solution was 80% sulphuric and 4% hydrofluoric acid (HF). Accordingly, 10% calcium gluconate and 5% sodium bicarbonate solution were administered intravenously under electrocardiographic monitoring. The burned sites were first washed with 5% sodium bicarbonate solution, followed by subcutaneous injection of 5% calcium gluconate solution. Emergency tangential escharectomy was performed, and the excised wounds were treated by a wet compress of 10% calcium gluconate solution and covered with xenografts. After surgery, the patient's vital signs were stable without evident electrolyte imbalance. The patient received autografts on the 7th day, and was discharged by the 20th day post-burn.

Fig. 1. Chemical burns of lower limbs due to exposing to a mixture of sulphuric acid and hydrofluoric acid. (A) shows the wound surfaces appearing brown with blisters on the admission. (B) shows the changes of wound appearance about 1.5 h post burn. The black arrows indicate the erythma on the surrounded normal skin (colour version of this figure can be found in the online version at www.informahealthcare.com/ctx).

Concentrated sulphuric acid causes coagulative tissue necrosis, which is conservatively treated. HF burns can be life-threatening, since the released fluoride ions can cause electrolyte imbalance and severe arrhythmia by binding to calcium and magnesium ions.¹ Death has been reported from HF burns of 2.5% total body surface area or TBSA.² Treatment should be immediately undertaken for patients with HF injuries,³ such as removal of clothing and copious irrigation.⁴ For patients with mixed-acid burns, like the patient described here, the diagnosis could be difficult. The chemical constituents should be identified quickly so as not to delay appropriate treatment. Nonspecific signs and symptoms of HF burns, such as severe pain and patchy erythema, should be concerning. The laboratory tests in this case revealed hypocalcaemia and high urinary fluoride, suggesting the fluoride poisoning. Since HF penetrates the entire skin in several minutes,⁵ antidotes such as calcium gluconate solution should be used immediately to block the ongoing absorption of HF.¹ Due to the potential risk of sulphuric acid burns accelerating HF absorption, emergency escharectomy was performed for more thorough debridement in this case. Taking safety measures at the workplace to avoid similar events is necessary.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.