POTD: Hydrofluoric Acid Burn

>> Overview:

  • Used in a variety of industries, including plastic, dye, semiconductor, and fertilizer manufacturing, beer fermentation, and in petroleum production

  • Also found in rust remover, various pesticides, refrigerants, car wash cleaning products, and detergents

  • Cutaneous exposures are most common

  • Dilute aqueous HF is a weak acid, but at concentrations > 20%, severe and potentially lethal burns can occur

  • HF is lipophilic and highly penetrative; causes deep tissue destruction via liquefactive necrosis

    • Once within the tissues, the fluoride ion complexes with calcium and magnesium, causing their depletion

    • Hyperkalemia results from increased cellular permeability

>> Clinical Presentation:

  • Pain out of proportion to the exam; discomfort often described as severe throbbing

  • Exposures to concentrations > 50% cause immediate pain and tissue damage

    • This may include erythema, blistering, ulceration, underlying bone damage, and tenosynovitis

  • Systemic toxicity develops more slowly

    • Can manifest as nausea, vomiting, abdominal pain, renal failure, hepatic failure, seizure, hypotension, dysrhythmia, or heart failure

  • Electrolyte abnormalities (hypocalcemia, hypomagnesemia, and hyperkalemia) are common

  • Coagulopathy may develop secondary to hypocalcemia

>> Work Up:

  • 12-lead EKG to evaluate for dysrhythmia and interval abnormalities

    • Prolongation of the QTc interval is one of the best indicators of systemic HF toxicity

  • Pts with significant exposures require continuous cardiac monitoring

>> Management:

  • Irrigation:

    • Immediately irrigate with water for 15-30 minutes to remove and dilute the acid

    • Irrigation will not effectively remove HF that has already penetrated into deeper tissue

  • Calcium gluconate gel (topical):

    • Turns the fluoride into an insoluble salt, preventing further absorption

      • This reduces the amount of tissue destruction and systemic toxicity

    • Apply gel to affected areas every 30 minutes

      • Once pain is controlled, reduce frequency to every 4 hours

    • Gel can be prepared by combining 100 mL of water-based lubricant with 2.5 g of calcium gluconate

  • Calcium gluconate infiltration:

    • Allows for much greater skin penetration than topical application; its use should be considered for significant burns

    • Infiltration is performed with a small gauge needle (25- or 27-gauge)

      • Inject approximately 0.5 mL/cm2 of 5% calcium gluconate into the affected skin and subcutaneous tissue

      • For finger injuries, do not exceed 0.5 mL per phalanx to prevent an excessive rise in compartment pressure

  • Calcium gluconate, intravenous:

    • Should be administered intravenously following significant exposures and in cases of hypocalcemia

    • Intravenous calcium gluconate decreases pain and prevents extension of the burn to deeper tissues

    • For extremity burns, regional intravenous calcium gluconate may be administered via Bier block

      • Tourniquet is placed proximal to burn; calcium gluconate is administered intravenously distal to tourniquet

      • Can inject 10 mL of 10% calcium gluconate diluted in 30 - 40 mL of normal saline and maintain for 20 - 25 min

  • Calcium gluconate, arterial:

    • High incidence of complications (arterial spasm, necrosis, dysrhythmia, and vasculitis)

    • No demonstrable benefit when compared to intravenous calcium gluconate for most HF exposures

    • Intra-arterial calcium is theoretically advantageous in severe burns affecting tissues with clear arterial distribution and in small spaces that cannot accommodate large volumes of locally-infiltrated calcium

  • **Resolution of pain is a good indicator of treatment efficacy**

>> Non-Dermal Exposures:

  • Inhalation:

    • Consider the possibility of inhalational exposure in any patient with HF burns to the face, head, or neck, as well as in burns sustained in confined spaces

    • May cause fever, chills, pulmonary edema, hemorrhage, chest discomfort, cyanosis, and wheezing

    • Obtain chest radiography and provide supplemental oxygen

    • Consider nebulized calcium gluconate (2-3%), PPV, and intubation in severe cases

  • Ocular:

    • An ophthalmologic emergency; irrigation is the immediate priority

    • Consider administration of calcium gluconate (1-10%) eye drops

    • Instill 1-2 drops every 2-3 hours into the affected eye(s)

  • Fingernail:

    • HF easily penetrates the nail

    • Removal is generally required to apply calcium gluconate gel to affected nailbed

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