Hydrofluoric Acid

1. Hydrofluoric Acid Intensive Review Course in Clinical Toxicology 2007 Rama B. Rao

2. Hydrofluoric Acid (HF) • Household • Glass etching • Cleaning bricks and porcelain • Rust removal • Industrial • Leather tanning • Electroplating • Etching microchips

3. Hydrofluoric Acid • pKa 3.5 • Weak Acid • Permeability coefficient 1.4 x 1024cm/sec • Concentrations of HF • Household (aqueous) 3-40% • Industrial (aqueous) >70% • Anhydrous HF 100%

4. Pathophysiology • Deep penetration of tissues • Fluoride binding of divalent cations • Calcium • Magnesium • Alters Calcium dependent Potassium channels

5. Routes of Exposure • Dermal • Inhalational • Oral • Ocular

6. HF Clinical Presentation: • Local • Systemic

7. Hypocalcemia Hypomagnesemia Hyperkalemia Prolonged QT Bleeding Prolonged QT Torsades ECG changes Systemic HF

8. Assessment: Systemic HF • Vital signs • Mental status • ECG • Hyperkalemia • Peaked T waves • Progression to sine waves • QT prolongation • Ventricular dysrhythmias, ectopy

9. Laboratory Indicators Systemic HF • Acidemia • Prolonged PT (or bleeding) • Electrolytes: iCa2+, Mg2+, K+

10. Management Systemic HF • Continuous ECG Monitoring • 2+ large bore IVs, foley • Laboratory: • Ca2+, Mg2+ , electrolytes, CBC • Type and Screen • PT/PTT • ABG or VBG

11. Therapy Systemic HF • Restore electrolyte homeostasis • Decontamination • Enhancement of urinary excretion F- • Treatment of dysrhythmias

12. Calcium • Cardioprotective, restorative • Dosing: • 1 gm IV over 5 minutes • Titrate to ECG effect • May require grams • Pediatrics: • 20-60 mg/Kg • Monitor concentrations

13. Calcium Preparations (10%) • Calcium gluconate • 0.465 mEq/mL • Peripheral lines • 60 mg/kg pediatric • Calcium chloride • 1.36 mEq/mL • Central line • 20 mg/kg pediatric

14. Magnesium sulfate 20% • Adults • 20 ml (4 gm) over 20 minutes* • Cautious/avoid in renal failure • Observe vascular, neurological effects • Pediatrics • 25-50 mg/kg/dose over 20 minutes

15. NaHCO3 • Urinary alkalinization/Ion trapping F- • 1-2 mEq/kg bolus • Isotonic drip at 1.5 –2 x maintenance • Serum pH 7.5-7.55 • No potassium supplementation without absolute indication

16. Dysrhythmias • Correct underlying derangements • In refractory cases: • Amiodarone • In vitro • Animal models with HF induced hyperkalemia • Human data lacking

17. HF Ingestions

18. HF Ingestions • Readily absorbed • High fatality rate • Assume all ingestions are systemic exposures

19. HF Ingestions: Clinical Presentation • Vomiting • Dysrhythmias • Rapid deterioration • Caustic injury minor

20. HF Decontamination • Removal of gastric contents* • Careful NGT suction • Use caution as provider • Delivery cations to GI tract • Calcium carbonate • Magnesium citrate

21. Inhalational HF • Assume exposure with any dermal exposure to the face • Burning, stridor • Dyspnea • Bronchospasm • Presume associated systemic and ocular toxicity

22. Inhalational HF • Airway management prn • Screen for systemic, ocular toxicity • Nebulization therapy • 2.5 - 5 % Calcium gluconate • (Dilution of a 10% solution) • Limited data

23. Ocular HF • Assume in inhalational exposures • Screen for additional facial/systemic exposures • Irrigation 1L LR • Avoid calcium or magnesium application*

24. Dermal HF • Most common presentation • Evaluate for systemic toxicity if: • Vital sign abnormalities • Facial/neck exposures • Alteration mental status • High concentration solution • Large body surface area • any concentration

25. Dermal HF • Severe pain with few findings • Onset pain often related to concentration

26. Dermal HF

27. Dermal HF • Irrigation with soap and water • Topical calcium • Sterile water soluble lubricant • 3.5 gm CaGluconate powder in 150 mL • 25 mL of 10% CaGluconate in 75 mL • Can consider • calcium carbonate • Calcium chloride • Consider filling glove if hand exposure

28. Dermal HF • Local intradermal injection calcium • 0.5 mL/cm3 of 5% calcium gluconate • Distal to injury • Limited utility esp in digits

29. Dermal HF • Intra-arterial Calcium • Hand injuries • Careful placement arterial line on AFFECTED side

32. Intra-Arterial Calcium • 10 mL of 10% Calcium gluconate in 40 mL D5W or NS • Infuse over 4 hours • Repeat prn Huisman LC, et al. Lancet. 2001;358:1510.

33. Dermal HF • Digital blocks useful • Single digit/tip • Delayed presentations • No systemic toxicity • “Bier” blocks • 25 mL of 2.5% CaGlu • Limited utility: tourniquet

34. HF Summary • Rapid screening for systemic toxicity • Intravascular Calcium administration: • Gluconate unless central venous line • Adjunctive pain control

35. Acknowledgements • Lewis Nelson • Susi Vassallo • NYCPCC