Difference between revisions of "Hydrofluoric acid"

Revision as of 06:14, 7 May 2017

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

Hydrofluoric acid burn

• Skin
  • Burns
• Ophthalmic
  • Eye pain
  • Erythema
• Ingestion
  • nausea and vomiting
  • Abdominal pain
• 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
• 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 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

Evaluation

• Trend calcium and potassium levels
  • HF acid chelates calcium and poisons the Na+/K+ pump
  • Order serial chemistries, ECGs
  • Expect hypocalcemia and hyperkalemia
• Obtain other electrolytes including magnesium
  • Can get hypomagnesemia

Management

• Remove soiled clothing and irrigate thoroughly

Cutaneous Burns

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 OR
    • Mix 25mL 10% calcium gluconate solution with 75mL water-soluble lubricant
  • 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 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

Ocular burns

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

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
  • Consider intubation

Inhalation

• 100% O2 by facemask
• nebulized 2.5% calcium gluconate
• Follow ECG, electrolytes, and vitals
• Low threshold for obs/admission

Systemic toxicity

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

• Levine MD, Zane R: Chemical Injuries, in Marx JA, Hockberger RS, Walls RM, et al (eds): Rosen’s Emergency Medicine: Concepts and Clinical Practice, ed 8. St. Louis, Mosby, Inc., 2013, (Ch) 64: pp 818-822.