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

Clinical Features

• Onset and severity of symptoms correlated w/ concentration
  • Dilute solutions (<20%) may have delayed onset up to 24hr post-exposure
  • Moderate solutions (20-50%) develop symptoms w/in 1-8hr
  • Concentrated solutions (>50%) develop symptoms immediately
    • These pts are at highest risk for systemic toxicity/death
    • Pain immediately (even if wound appears minor) implies severe injury
• Burn itself is usually relatively minor
• Toxicity caused by binding of calcium

Diagnosis

• Trend calcium and potassium levels
  • HF acid chelates calcium and poisons the Na+/K+ pump
  • Order serial chemistries, EKGs

Management

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

1. Copious irrigation
2. Application of gel paste of Ca gluconate or benzalkonium Cl
   1. Rub into affected area for 10-15min w/ pain relief being used as end-point of tx
   2. Calcium gel is commercially available (found in industrial first-aid kits)
   3. Calcium gel can be made:
      1. Mix calcium gluconate powder 3.5gm w/ 150mL water-soluble lubricant OR
      2. Mix 25mL 10% calcium gluconate solution w/ 75mL water-soluble lubricant
   4. Benzalkonium Cl is commercially available
   5. If calcium gluconate is not available calcium chloride can be used

• Severe injuries

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

• Refractory injuries

1. Treat w/ intra-arterial infusion of calcium gluconate
   1. Deliver via arterial line placed proximal to injury in the same limb
   2. Infuse 10mL of 10% Ca gluconate dilued in 40mL of NS or D5water over 4 hr

• Ingestion

1. If <1hr of ingestion place NG tube, suction, gastric lavage
   1. Follow lavage by 300mL 10% Ca gluconate down NGT
   2. Provide aggressive IV supplementation if ECG signs of hypoCa or hyperK

• Hyperkalemia and Hypocalcemia

1. Treat medically as needed

See Also

• Caustics