HYDROFLUORIC ACID EXPOSURE - January 2017
Paramedics respond to a chemical manufacturing plant after an employee was exposed to a chemical spill. The employee is a 29 year-old male complaining of severe pain to his left arm, chest and neck as well as mild shortness of breath. He states he was splashed when transferring the chemical between containers. The exposure occurred approximately 25 minutes prior to paramedic arrival. The patient states that he rinsed off in the shower but the pain continues to increase. His supervisor identifies the chemical as 70% hydrofluoric acid and informs the paramedics that he has initiated treatment with a topical calcium gluconate gel and nebulized solution from the “HF Kit” per company protocol.
On evaluation the patient is sitting in a chair, and appears to be in severe pain. He is receiving a nebulizer treatment. His vital signs: BP 148/90; HR 96; RR 26; oxygen saturation 94%. On lung exam the patient is tachypneic with bilateral rhonchi. The patient’s left arm, left upper chest and left side of his neck are erythematous and covered by a clear gel. Within the exposed area on the patient’s arm there is central blanching.
What is hydrofluoric acid?
Hydrofluoric acid (HF) is an inorganic acid used for many industrial applications. It is used in both gaseous and aqueous forms. Exposure to HF may result in severe local and systemic effects through depletion of available calcium and magnesium, both vital to cellular function, and by causing hyperkalemia. The extent of injury following HF exposure depends up on the volume, concentration and duration of exposure. High concentration (>50%) dermal exposures will cause immediate pain and tissue damage, whereas low concentration (<20%) exposure may not cause symptoms for up to 24 hours. While dermal exposures are most common, patients may experience exposures via pulmonary, ocular or gastrointestinal routes. Systemic toxicity may result from any route of exposure due to the ability of HF to penetrate tissue. Risk factors for systemic toxicity include: oral and inhalation exposure, exposure of >5% body surface area, exposure to HF concentrations of >50%, and head and neck burns. Systemic effects include severe electrolyte disturbances (hypocalcemia, hypomagnesemia and hyperkalemia) and associated life threatening cardiac dysrhythmias. Prompt recognition of exposure, decontamination and appropriate treatment will reduce associated morbidity and mortality.
How is hydrofluoric acid exposure managed?
Goals for prehospital treatment after HF exposure are:
- Rapid treatment of localized and systemic hypocalcemia
- Monitoring for cardiac dysrhythmia and treatment for life threatening cardiac or respiratory instability
- Immediate transport with pain control
The first step in managing HF exposure is to immediately remove clothing and irrigate the skin with tap water for 15 to 30 minutes before topical treatment or transport to the emergency department (ED). Prehospital providers should use standard personal protective equipment. Some industrial settings have developed management protocols and treatment may be in progress prior to contact with EMS. Protocols may include massaging 2.5% calcium gluconate (CG) gel into affected areas. Calcium gluconate is used to bind HF, preventing it from getting absorbed and causing toxicity. Assuming an exposed patient has been properly irrigated, the patient may be transported with topical calcium gluconate gel in place. Calcium gluconate nebulizer treatments may have been initiated for pulmonary exposure and CG eye irrigation may have been initiated for ocular exposure. If the patient is hemodynamically stable, one should allow for completion these treatments prior to transport. If the patient deteriorates, begin bag-valve-mask ventilation and immediately contact the base hospital for an order for calcium chloride IV push.
After their initial assessment, how should the paramedics proceed in the management of this patient?
Recognizing the hazardous materials exposure, paramedics immediately contact the Medical Alert Center for assistance. Table 1 below provides an overview of the prehospital management of hydrofluoric acid. They are instructed to leave the gel in place and allow the patient to finish the nebulizer treatment as long as he remains hemodynamically stable. They contact their base hospital and, after completion of the CG nebulizer treatment, transport the patient to the closest receiving hospital.
TABLE 1: HYDROFLUORIC ACID EXPOSURE - PREHOSPITAL MANAGEMENT
- For dermal exposures, immediately remove clothing and irrigate the skin with tap water for 15 to 30 minutes before transport to the ED; cover with blanket for transport. (See 1202 General ALS).
- Industrial facilities with treatment protocols may have already initiated treatment:
- Patients may be transported with topical CG gel in place, do not remove.
- CG nebulizer treatments may have been initiated for pulmonary exposure. If patient is hemodynamically stable, allow for completion of nebulizer treatment prior to transport.
- If patient has severe shortness of breath with hypoxia < 94% or ALOC, initiate NRB 15 L/min oxygen; place on a cardiac monitor and pulse oximetry. (See MCG 1304)
- Eye irrigation may have been initiated for ocular exposure. If patient is hemodynamically stable, allow for completion of irrigation prior to transport. (See 1202 General ALS).
- Transport patient to an appropriate receiving facility (Adults MAR or for children to EDAP or PMC per 510 Pediatric Destination.
Shortly after arrival to the ED, the patient becomes pulseless and unresponsive. The monitor shows ventricular fibrillation. CPR is initiated and the patient is promptly defibrillated without response. During the next round of CPR, calcium and magnesium are pushed through the IV (Table 2 Emergency Department Management). The subsequent defibrillation attempt is successful. The patient was found to have severe hypocalcemia requiring multiple doses of IV CG. He is admitted to the ICU where he recovers over the next 4 days.
TABLE 2: HYDROFLUORIC ACID EXPOSURE EMERGENCY DEPARTMENT MANAGEMENT
- Dermal exposures: Immediately remove clothing and irrigate the skin with tap water for 15 to 30 minutes before transport to the ED.
- After irrigation, massage 2.5% calcium gluconate (CG) gel into the affected area until pain subsides and repeat as necessary. 2.5% CG gel can be prepared by mixing 25mL of 10% CG solution with 75mL of water-soluble lubricant or mixing 2.5g of CG powder with 100mL of water-soluble lubricant.
- If topical CG gel fails to relieve pain, consider intradermal injections with 5% to 10% calcium gluconate. Inject no more than 0.5mL/cm2 and monitor for compartment syndrome in at risk areas.
- Consider intraarterial infusion of 2% calcium gluconate or Bier block with 2.5% calcium gluconate for large wounds or affected areas not amenable to intradermal injections. Prepare 2% calcium gluconate by mixing 10mL of 10% calcium gluconate solution with 40mL of D₅W or normal saline. For 2.5% calcium gluconate mix 10mL of 10% calcium gluconate solution with 30mL of D₅W or normal saline.
- Inhalational exposure: Treat with 2.5% nebulized calcium gluconate. Mix 25ml of 10% calcium gluconate with 75ml normal saline and nebulize 4mL per treatment.
- Ingestion: Absorption is rapid and often fatal. Consider gastric lavage with nasogastric tube if ingestion is within 60 minutes. Give calcium or magnesium salt solution (calcium gluconate, calcium chloride, magnesium citrate, magnesium sulfate) orally or by nasogastric tube.
- Ocular exposure: Irrigate each eye with 1 L of normal saline. Consider 1% calcium gluconate drops after irrigation. Prepare eye drops by mixing 10mL of 10% calcium gluconate with 90mL of normal saline.
- Systemic Toxicity: For patients with suspected severe toxicity, immediately initiate treatment with intravenous calcium and magnesium salts.
- Infuse 0.1-0.2 mL/kg 10% calcium gluconate (up to 10 mL) over 10 minutes and repeat as necessary.
- Infuse 25-50 mg/kg of magnesium sulfate (up to 4g) over 20 minutes and repeat as necessary.
- Perform ECG to assess for signs of hypocalcemia, hypomagnesemia and hyperkalemia.
- Place patient on cardiac monitor.
- Rapidly assess serum electrolytes and recheck every 2-4 hours
- Consider hemodialysis for severe HF poisoning.
- Patients may require large quantities of calcium gluconate. If hospital supply is insufficient, contact the Medical Alert Center (MAC) at the LA County EMS Agency for additional resources. The MAC may be contacted via ReddiNet or by calling directly (866) 940-4401.
- Consider contacting the California Poison Control Center for assistance. (800) 222-1222
Take Home Points
- Exposure to HF may result in severe local and systemic effects from hypocalcemia and hyperkalemia.
- Decontamination by removal of clothing and irrigation with water is the first step in management.
- Paramedics should consider contacting the Medical Alert Center for assistance in managing patients exposed to hazardous materials, such as HFA.
- Optimal treatment is with calcium gluconate preparations but if the patient is in extremis, consider pushing calcium chloride with an order from the base hospital.
- HF exposure may be lethal and transport should not be delayed if there is any respiratory distress or hemodynamic instability.
Su M (2011) Chapter 105. Hydrofluoric Acid and Fluorides. In: Su M, ed. Goldfrank's Toxicologic Emergencies. 9th ed. New York.
Makarovsky I, Markel G, Dushnitsky T, Eisenkraft A. Hydrogen fluoride-the protoplasmic poison. Isr Med Assoc J. 2008;10(5):381–385.
McKee D, Thoma A, Bailey K, Fish J. A review of hydrofluoric acid burn management. Plast Surg (Oakv). 2014 Summer;22(2):95-8. Review.
By Kevin Andruss, MD, EMS Consultant, Los Angeles EMS Agency
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