What is the treatment for a patient with hydrofluoric (HF) acid chemical burns?

Hydrofluoric Acid Burns: Pathophysiology and Treatment

Pathophysiology

Hydrofluoric acid (HF) causes uniquely destructive chemical burns through fluoride ion penetration that depletes cellular calcium and magnesium, leading to liquefaction necrosis, severe pain, and potentially lethal systemic toxicity. 1, 2

• The fluoride ion penetrates deeply into tissues and binds calcium and magnesium cations, interfering with calcium-dependent cellular processes and membrane function 3, 1
• Unlike typical acid burns, HF burns may have delayed onset of symptoms (hours to days) depending on acid concentration, making initial recognition challenging 1, 2
• Continued fluoride ion activity causes progressive liquefaction necrosis of soft tissues and bony erosion if untreated 2
• Systemic absorption can lead to life-threatening hypocalcemia, hyperkalemia, and cardiac arrhythmias 1, 2

Immediate First Aid Treatment

Begin copious water irrigation immediately within 3 minutes of exposure and continue for at least 15 minutes, as this is the single most critical intervention to reduce morbidity. 4

• Remove all contaminated clothing and jewelry immediately to prevent trapping chemicals against skin 4
• Industrial settings show that immediate irrigation (within 3 minutes) significantly reduces full-thickness burns, hospital days, and delayed complications compared to delayed irrigation 4
• For eye exposures, immediate irrigation with large amounts of tap water is beneficial, though specialized solutions like Hexafluorine® may be more efficient than water for HF-specific eye burns 4
• Personal protective equipment must be worn by rescuers to avoid contamination 4

Definitive Medical Treatment

Topical Calcium Therapy (First-Line for Minor Burns)

Apply calcium gluconate gel (2.5-10%) topically to affected areas immediately after irrigation for superficial or limited HF burns. 1, 5

• Massage the gel into affected areas continuously for 15-30 minutes and repeat as needed for pain relief 1, 5
• This provides calcium to neutralize fluoride ions at the burn site 1
• Topical magnesium salts are an alternative option 3, 1

Subcutaneous/Intradermal Calcium Injection (Moderate Burns)

For more severe burns with persistent pain despite topical treatment, inject 5-10% calcium gluconate subcutaneously or intradermally around and beneath the burn using a 27-30 gauge needle (0.5 mL per cm² of affected area, maximum 0.5 mL per digit). 1, 5, 2

• This delivers calcium directly to affected tissues to complex with fluoride ions 3, 2
• Digital burns may require nail removal for direct injection into the nail bed, though intraarterial infusion can avoid this painful procedure 3, 1
• Repeat injections may be necessary if pain recurs 5, 2

Intraarterial Calcium Infusion (Severe Digital Burns)

For moderate to severe HF burns involving fingers, intraarterial calcium infusion of dilute (1.66%) calcium gluconate or calcium chloride provides superior outcomes and avoids debilitating procedures like fingernail removal. 3

• Infuse dilute calcium salts via percutaneous arterial line for 4 hours, repeating 1-3 times as needed 3
• This ensures all affected cells receive adequate calcium to replenish depleted stores and complex with fluoride ions 3
• Provides excellent pain relief and marked improvement of burn lesions 3
• Eliminates the need for painful direct fingertip injections and nail removal 3
• Monitor for transient arterial spasm at insertion site 3

Systemic Monitoring and Support

Monitor serum calcium, magnesium, potassium, and continuous ECG for all significant HF exposures, as systemic fluoride absorption can cause life-threatening electrolyte disturbances and cardiac arrhythmias. 1, 2

• Aggressively replace calcium deficiency with intravenous calcium gluconate or calcium chloride as needed 2
• Calcium gluconate injection (10% solution, 100mg/mL) is available for IV administration 6
• Monitor for hypocalcemia, hyperkalemia, and cardiac dysrhythmias 2
• Severe metabolic acidosis may indicate need for additional interventions 7

Special Considerations

Inhalation Injury

Patients with faciocervical HF burns or suspected inhalation injury require immediate airway assessment, respiratory support, and aggressive systemic treatment due to high mortality risk. 7

• Assess for respiratory distress, wheezes, and signs of airway compromise 7
• Timely respiratory tract care and systematic support are vital for survival 7
• These cases are extremely complex and require intensive care management 7

Pain Management

HF burns cause severe, persistent pain that requires multimodal analgesia titrated to validated pain scales, with consideration of IV ketamine for refractory pain. 4

• The pain is often disproportionate to visible injury due to deep fluoride ion penetration 1
• Persistent pain despite calcium therapy indicates inadequate fluoride neutralization and need for additional treatment 1, 5

Critical Pitfalls to Avoid

• Never delay treatment waiting for symptoms to develop - HF burns with delayed presentation (>1 hour after exposure) indicate higher concentration exposure and worse prognosis 1
• Never underestimate small surface area burns - even limited HF exposure can cause severe systemic toxicity and death 1, 2
• Never use standard burn protocols alone - HF requires specific calcium-based therapy beyond routine burn care 1, 5
• Never discharge patients without ensuring adequate calcium therapy and pain control - continued pain indicates ongoing fluoride-mediated tissue destruction 1, 5

Treatment Algorithm Summary

1. Immediate irrigation with copious water for ≥15 minutes 4
2. Topical calcium gluconate gel for all burns 1, 5
3. Subcutaneous calcium injection if pain persists after topical therapy 1, 5, 2
4. Intraarterial calcium infusion for severe digital burns 3
5. Systemic monitoring and calcium replacement for significant exposures 2
6. Specialized burn center referral for extensive burns or systemic toxicity 5