Hydrofluoric acid

Background

  • Used in both commercial and home setting
    • Rust remover (most common home use)
    • Glass etching, chrome and other metal cleaning, petroleum processing
  • Oral ingestion has very high mortality rate
  • Onset and severity of symptoms correlated with concentration
    • Dilute solutions (<20%) may have delayed onset up to 24hr post-exposure
    • Moderate solutions (20-50%) develop symptoms within 1-8hr
    • Concentrated solutions (>50%) develop symptoms immediately
      • These patients are at highest risk for systemic toxicity/death
      • Pain immediately (even if wound appears minor) implies severe injury
  • Burn itself may appear relatively minor
  • Toxicity caused by binding of calcium and magnesium leading to electrolyte derangement and myocardial dysfunction

Clinical Features

  • Skin exposure
    • Burns
    • Pain out of proportion to extent of burn
  • Ophthalmic exposure
    • Eye pain
    • Erythema
  • Ingestion
  • Inhalation
    • Shortness of breath
    • Throat pain/burning
  • Signs/symptoms of hypocalcemia and hypomagnesemia
    • Can lead to QTc interval prolongation and cardiac arrhythmias, the primary cause of death in HF burns

Differential Diagnosis

Caustic Burns

Evaluation

Management

  • Decontamination: remove soiled clothing and irrigate thoroughly.
  • Mainstay of treatment is application of calcium to affected area.

Minor injuries (<50 cm2 from dilute solutions <20%)

  • Application of gel paste of Ca gluconate or benzalkonium Cl
    • Rub into affected area for 10-15min with pain relief being used as end-point of treatment
    • Calcium gel is commercially available (found in industrial first-aid kits)
    • Calcium gel can be made:
      • Mix calcium gluconate powder 3.5gm with 150mL water-soluble lubricant (KY-Jelly) OR
      • Mix 25mL 10% calcium gluconate solution with 75mL water-soluble lubricant (KY-Jelly)
    • Benzalkonium Cl is commercially available
    • If calcium gluconate is not available calcium chloride can be used

Severe injuries

  • Treat with intradermal injections of 5% calcium gluconate
    • Prepare by diluting conventional 10% Ca gluconate with sterile NS in 1:1 ratio
    • Inject in and around the burned area in amount not to exceed 0.5mL per cm2

Refractory injuries

  • Treat with intravenous infusion of calcium gluconate using Bier block
    • Place tourniquet proximal to exposure site on affected extremity and inject though IV distal to tourniquet
    • Inject 10 mL of 10% Ca gluconate diluted in 40 mL of saline and remove tourniquet after 20 min of dwell time
  • In severe refractory cases may also infuse intra-arterial calcium gluconate
    • Deliver via arterial line placed proximal to injury in the same limb
    • Infuse 10 mL of 10% Ca gluconate diluted in 40mL of saline over 4 hr

Ocular burns

  • Irrigate with saline for at least 5 min
  • If persistent pain administer 1% calcium gluconate to eye (dilute 10% calcium gluconate with normal saline)
    • Consult ophthalmology due to irritation effect of calcium salts to eye

Ingestion

  • If <1hr of ingestion, may consider NG tube for suction and gastric lavage
    • Follow lavage by 300mL 10% Ca gluconate down NGT
  • Consider intubation for airway protection

Inhalation

  • Consider in any patient with facial burns or exposure to HF in confined space
  • Oxygen via NRB
  • Nebulized 2.5% calcium gluconate
  • Intubation may be required in severe cases

Systemic toxicity

  • Administer calcium gluconate 100mg IV (10 mL of a 10% solution) over 2-3 minutes
  • May also need to replete magnesium (4g IV over 20 minutes)
  • May see QTc prolongation, cardiac arrhythmia, or obvious systemic illness
  • Treat hyperkalemia as needed

Disposition

  • Consultation with poison center and burn center transfer per Burn center criteria
  • Admission for all patients with arrhythmia on ECG or severe electrolyte disturbance

See Also

  • Caustics
  • Burn

References

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