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Hydrofluoric Acid Burns
Updated: Jan 28, 2010
Introduction
Background
Hydrofluoric (HF) acid, one of the strongest inorganic acids, is used mainly for industrial purposes (eg, glass etching, metal cleaning, electronics manufacturing). Hydrofluoric acid also may be found in home rust removers. Exposure usually is unintentional and often is due to inadequate use of protective measures.
Hydrofluoric acid burns are a unique clinical entity. Dilute solutions deeply penetrate before dissociating, thus causing delayed injury and symptoms. Burns to the fingers and nail beds may leave the overlying nails intact, and pain may be severe with little surface abnormality.
Severe burns occur after exposure of concentrated (ie, 50% or stronger solution) hydrofluoric acid to 1% or more body surface area (BSA), exposure to hydrofluoric acid of any concentration to 5% or more BSA, or inhalation of hydrofluoric acid fumes from a 60% or stronger solution. The vast majority of cases involve only small areas of exposure, usually on the digits.
A unique feature of HF exposure is its ability to cause significant systemic toxicity due to fluoride poisoning.
Pathophysiology
The 2 mechanisms that cause tissue damage are corrosive burn from the free hydrogen ions and chemical burn from tissue penetration of the fluoride ions.
Fluoride ions penetrate and form insoluble salts with calcium and magnesium. Soluble salts also are formed with other cations but dissociate rapidly. Consequently, fluoride ions release, and further tissue destruction occurs.
Systemic toxicity occurs secondary to depletion of total body stores of calcium and magnesium, resulting in enzymatic and cellular dysfunction, and ultimately in cell death. Majority of deaths are resulting from cardiac arrhythmias that were precipitated by hypocalcaemia and consequent hyperkalemia.1
Frequency
United States
More than 1000 cases of hydrofluoric acid exposure are reported annually. Actual incidence rate is unknown.
In a review of 15 years' experience with hydrofluoric acid burns at one center, hydrofluoric acid burns accounted for 35 (17%) patients out of 205 who were admitted for chemical burns; all of these patients were men.2
Mortality/Morbidity
- Local effects of hydrofluoric acid burns include tissue destruction and necrosis. Burns may involve underlying bone.
- Systemic fluoride ion poisoning from severe burns may be associated with hypocalcemia, hyperkalemia, hypomagnesemia, and sudden death.
- Deaths have been reported from concentrated acid burns to as little as 2.5% BSA.
Sex
Males are affected more commonly by hydrofluoric acid burns, which reflects occupational patterns.
Age
The majority of hydrofluoric acid exposures occurs in adults.
Clinical
History
- Time of exposure to onset of symptoms is related to the concentration of the hydrofluoric acid:
- Solutions of 14.5% and higher concentrations immediately produce symptoms.
- Solutions of 12% may take up to an hour to produce symptoms.
- Solutions of less than 7% may take several hours before onset of symptoms, resulting in delayed presentation, deeper penetration of the undissociated HF acid, and a more severe burn.
- Concentrated solutions cause immediate pain and produce surface burns similar to those produced by other common acids (eg, erythema, blistering, necrosis).
- Pain typically is described as deep, burning, or throbbing.
- Pain often is disproportionate to apparent skin involvement.
- Obtain history of potential exposure to cleaning solutions within the last 24 hours, to include the following:
- Duration and type of exposure
- Skin
- Ophthalmic
- Gastrointestinal (vomiting, abdominal pain)
- Pulmonary (throat burning, dyspnea)
- Concentration of acid
- Use of protective measures
- Other agents in the solution
- Symptoms of hypocalcemia
- Tetany
- Chvostek sign
- Trousseau sign
- Cardiac arrhythmias
- Duration and type of exposure
- Additionally, obtain history of medications and intercurrent illness that predispose patient to hypocalcemia or hypomagnesemia.
Physical
- Weaker solutions penetrate before dissociating.
- Surface involvement in these cases is minimal and may be absent.
- Three categories of appearance include the following:
- Grade 1 - A white burn mark and/or erythema and pain; a grade 1 burn is shown in the photo below
Grade 1 hydrofluoric (HF) acid burns of the fingertips. The patient has severe pain (maximum middle digit) with only minimal redness of the nail beds.
{{mediacaption:773375_1}}- Grade 2 - A white burn mark and/or erythema and pain, plus edema and blistering
- Grade 3 - A white burn mark and/or erythema and pain, edema, and blistering, plus necrosis; a grade 3 burn is shown in the photo below
Grade 3 hydrofluoric (HF) acid burns of the fingertips. Note how the nailbed and tip of the fingers have severely been injured, but the nails show no damage.
{{mediacaption:773376_2}}
- Patients with inhalation burns may develop acute lung injury presenting with the following:
- Hypoxemia
- Stridor
- Wheezing
- Rhonchi
- Ocular burns may present with severe pain.
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References
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Further Reading
Keywords
hydrofluoric acid burn causes, HF acid burns, HF acid exposure, hydrofluoric acid burn treatment, hydrofluoric acid exposure, hydrofluoric acid burns
