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 1024

cm/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

Systemic HF Hypocalcemia

Hypomagnesemia

Hyperkalemia

Prolonged QT Bleeding

Prolonged QT Torsades

ECG changes

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

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

concentrationConcentration of HF (%)

Symptoms onset

<20 May not occur for 12-18 hours

20-50 Within 1-8 hours

>50 Immediate

Dermal HF

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