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Hydrofluoric Acid. Intensive Review Course in Clinical Toxicology 2007 Rama B. Rao. Hydrofluoric Acid (HF). Household Glass etching Cleaning bricks and porcelain Rust removal Industrial Leather tanning Electroplating Etching microchips. Hydrofluoric Acid. pK a 3.5 Weak Acid
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Hydrofluoric Acid Intensive Review Course in Clinical Toxicology 2007 Rama B. Rao
Hydrofluoric Acid (HF) • Household • Glass etching • Cleaning bricks and porcelain • Rust removal • Industrial • Leather tanning • Electroplating • Etching microchips
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%
Pathophysiology • Deep penetration of tissues • Fluoride binding of divalent cations • Calcium • Magnesium • Alters Calcium dependent Potassium channels
Routes of Exposure • Dermal • Inhalational • Oral • Ocular
HF Clinical Presentation: • Local • Systemic
Hypocalcemia Hypomagnesemia Hyperkalemia Prolonged QT Bleeding Prolonged QT Torsades ECG changes Systemic HF
Assessment: Systemic HF • Vital signs • Mental status • ECG • Hyperkalemia • Peaked T waves • Progression to sine waves • QT prolongation • Ventricular dysrhythmias, ectopy
Laboratory Indicators Systemic HF • Acidemia • Prolonged PT (or bleeding) • Electrolytes: iCa2+, Mg2+, K+
Management Systemic HF • Continuous ECG Monitoring • 2+ large bore IVs, foley • Laboratory: • Ca2+, Mg2+ , electrolytes, CBC • Type and Screen • PT/PTT • ABG or VBG
Therapy Systemic HF • Restore electrolyte homeostasis • Decontamination • Enhancement of urinary excretion F- • Treatment of dysrhythmias
Calcium • Cardioprotective, restorative • Dosing: • 1 gm IV over 5 minutes • Titrate to ECG effect • May require grams • Pediatrics: • 20-60 mg/Kg • Monitor concentrations
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
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
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
Dysrhythmias • Correct underlying derangements • In refractory cases: • Amiodarone • In vitro • Animal models with HF induced hyperkalemia • Human data lacking
HF Ingestions • Readily absorbed • High fatality rate • Assume all ingestions are systemic exposures
HF Ingestions: Clinical Presentation • Vomiting • Dysrhythmias • Rapid deterioration • Caustic injury minor
HF Decontamination • Removal of gastric contents* • Careful NGT suction • Use caution as provider • Delivery cations to GI tract • Calcium carbonate • Magnesium citrate
Inhalational HF • Assume exposure with any dermal exposure to the face • Burning, stridor • Dyspnea • Bronchospasm • Presume associated systemic and ocular toxicity
Inhalational HF • Airway management prn • Screen for systemic, ocular toxicity • Nebulization therapy • 2.5 - 5 % Calcium gluconate • (Dilution of a 10% solution) • Limited data
Ocular HF • Assume in inhalational exposures • Screen for additional facial/systemic exposures • Irrigation 1L LR • Avoid calcium or magnesium application*
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
Dermal HF • Severe pain with few findings • Onset pain often related to concentration
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
Dermal HF • Local intradermal injection calcium • 0.5 mL/cm3 of 5% calcium gluconate • Distal to injury • Limited utility esp in digits
Dermal HF • Intra-arterial Calcium • Hand injuries • Careful placement arterial line on AFFECTED side
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.
Dermal HF • Digital blocks useful • Single digit/tip • Delayed presentations • No systemic toxicity • “Bier” blocks • 25 mL of 2.5% CaGlu • Limited utility: tourniquet
HF Summary • Rapid screening for systemic toxicity • Intravascular Calcium administration: • Gluconate unless central venous line • Adjunctive pain control
Acknowledgements • Lewis Nelson • Susi Vassallo • NYCPCC