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
- Skin
- Burns
- Ophthalmic
- Eye pain
- Erythema
- Ingestion
- N/V
- Abdominal pain
- Inhalation
- Shortness of breath
- Throat pain/burning
- Signs/symptoms of hypocalcemia
- 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
Differential Diagnosis
Caustic Burns
- Caustic ingestion
- Caustic eye exposure (Caustic keratoconjunctivitis)
- Caustic dermal burn
- Airbag-related burns
- Hydrofluoric acid
- Tar burn
- Cement burn
Diagnosis
- Trend calcium and potassium levels
- HF acid chelates calcium and poisons the Na+/K+ pump
- Order serial chemistries, EKGs
- Expect hypocalcemia and hyperkalemia
- Obtain other electrolytes including magnesium
- Can get hypomagnesemia
Management
Minor injuries (<50 cm2 from dilute solutions <20%)
- Copious irrigation
- Application of gel paste of Ca gluconate or benzalkonium Cl
- Rub into affected area for 10-15min w/ pain relief being used as end-point of tx
- Calcium gel is commercially available (found in industrial first-aid kits)
- Calcium gel can be made:
- Mix calcium gluconate powder 3.5gm w/ 150mL water-soluble lubricant OR
- Mix 25mL 10% calcium gluconate solution w/ 75mL water-soluble lubricant
- Benzalkonium Cl is commercially available
- If calcium gluconate is not available calcium chloride can be used
Severe injuries
- Treat w/ intradermal injections of 5% calcium gluconate
- Prepare by diluting conventional 10% Ca gluconate w/ 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 w/ intra-arterial infusion of calcium gluconate
- Deliver via arterial line placed proximal to injury in the same limb
- Infuse 10mL of 10% Ca gluconate dilued in 40mL of NS or D5water over 4 hr
Ingestion
- If <1hr of ingestion place NG tube, suction, gastric lavage
- Follow lavage by 300mL 10% Ca gluconate down NGT
- Provide aggressive IV supplementation if ECG signs of hypoCa or hyperK
Hyperkalemia and Hypocalcemia
- Treat medically as needed