Hydrofluoric acid exposure

  • See also

    Poisoning – Acute Guidelines for Initial Management 

    Burns / management of burn wounds

    Key Points

    1. Topical exposure to Hydrofluoric Acid (HF) can cause systemic hypocalcaemia
    2. Pain may be delayed and disproportionate to external signs
    3. Local anaesthetic techniques are not appropriate for pain relief as they may mask ongoing symptoms.

    For 24 hour advice, contact Victorian Poisons Information Centre 131126

    Background

    • HF is corrosive, and systemically toxic by any route, due to fluorosis which manifests as hypocalcaemia.
    • HF is found in rust cleaners, car wheel cleaners (aluminium brightener) and is used in glass etching, as well as for industrial applications.
    • It is available in concentrations up to 70%, though in domestic applications is likely <5% 

    Assessment

    Patients requiring assessment 

    • All exposures should be medically assessed
    • Exposure associated with hypocalcaemia:
      •  >1% body surface area (BSA) with > 50% concentration HF
        • Greater than 5% BSA with any concentration
      • any ingestion as risk of systemic fluorosis

     History and examination

    • Determine if intentional exposure or accidental
    • Determine method of exposure (topical, ingested and inhaled), BSA exposed 
    • Systemic effects (fluorosis)
      • Due to exposure by any route
      • Symptoms of resultant hypocalcaemia and hypomagnesaemia, including:
        • Perioral numbness, paraesthesias, muscle cramps
        • Irritability, seizures
        • Tetany
        • Chovostek’s sign (facial muscle spasm)
        • Trosseau’s sign (carpal spasm)
        • Arrhythmias (long QT)
        • Heart failure
    • Dermal Exposure
      • Pain
        • Immediate with concentrations > 50% but will be delayed for up to 24 hours with weaker solutions.
        • Pain as marker of tissue destruction may be experienced before any external signs of blistering or skin erythema.
        • May be disproportionate to other clinical signs
      • Assessment of burns due to skin exposure (see burns CPG)
    • Ingestion
      • Assessment of oesophageal injury
      • Oesophageal irritation occurs with concentrations <20%. Burns may occur with higher than this.
    •  Inhalation
      • Respiratory distress
        • immediate irritation but cough, wheeze and SOB may be delayed.

    Always check for Medicalert bracelet in any unconscious patient, or any other signs of underlying medical condition (fingerprick marks etc)

    Investigations 

    • Electrolytes and blood gas - hypocalcaemia, hypomagnesaemia, hypo/hyperkalaemia,
    • ECG - prolonged QT is a marker of hypocalcaemia
    • Consider referral for urgent endoscopy in cases of ingestion 

    Acute Management

    First aid

    • Apply Calcium gluconate 2.5 % gel to contaminated skin. Repeat 15 minutely until pain has stopped.
    • If not available, an extemporaneous gel can be prepared by adding 10 mL of calcium gluconate injection 10% to 30 mL of sterile surgical lubricant.

    Decontamination 

    • Remove clothing and jewellery, bag in sealed containers and remove from patient care areas to protect other patients and health care workers from exposure
    • Wash off, including scrubbing under nails. Ensure that staff do not become contaminated - wear PPE, including chemical resistant gloves.
    • Flush eyes with 0.9% Saline,
    • Ingestion -  activated charcoal is not indicated.

    Resuscitation

    • All patients at risk of fluorosis need to be managed in a resuscitation area and have continuous cardiac monitoring. (This includes all ingestions) 
    • If cardiac arrest or ventricular arrhythmias:
      • 10 % Calcium gluconate
      • 0.5 mL/kg up to 60 mL (note: this dose is higher than standard maximum dose).
    • Plus IV Sodium bicarbonate8.4 % (1 mmol/ml)
      • 1 mL/kg  (1 mmol/kg)
    • Plus IV Magnesium sulfate 50 %, 2 mmol/mL:
      • For ventricular fibrillation 0.05 - 0.1 mL/kg (= 0.1 - 0.2 mmol/kg) slow IV
      • For deficiency 0.2 mL/kg (= 0.4 mmol/kg) over 4 hours

    Ongoing care and monitoring

    Supportive Rx

    • Correct hypocalcaemia:
      • Calcium gluconate 10%, 0.5mL/kg
      • May require repeated and higher doses. Discuss with a toxicologist
    • Correct hypocalcaemia and other electrolyte abnormalities
    • Skin exposure:
      • Calcium gluconate 2.5 % gel topically and repeated 15 minutely
    • Inhalational exposure:
      • Nebulised 1 mL Calcium gluconate 10 % in 3 mL 0.9 % sodium chloride.
    • Refractory pain:
      • Discuss with Poisons Information Centre 131126 regarding subcutaneous infiltration of Calcium gluconate 0.5 mL/cm2, regional IV infusion or intra-arterial infusion.
    • DO NOT use Calcium chloride for local or regional infiltration as this causes tissue damage   

    Consider consultation with local paediatric team when

    • Admission should be considered for all adolescent patients with an intentional overdose
      • Patients must be assessed for ongoing risk of deliberate self-harm on the ward before transfer to the ward to enable appropriate supervision and support. 
      • However, this should not delay urgent care, such as ICU admission.
    • Monitor for 12 hours if at risk of systemic fluorinosis

     Consult Contact Victorian Poisons Information Centre 131126 for advice

    Consider transfer to a tertiary centre when

    Patients requiring care outside the comfort level of the local hospital.

    For emergency advice and paediatric or neonatal ICU transfers, call the Paediatric Infant Perinatal Emergency Retrieval (PIPER) Service: 1300 137 650.

     Consider Discharge when

    • Pain can be controlled with simple analgesia only
    • Normal GCS
    • Normal ECG (if required)
    • Period of observation as above
    • For deliberate ingestion a risk assessment should indicate that the patient is at low risk of further self-harm in the discharge setting

    Discharge information and follow-up:

    For Children who DO NOT NEED hospital admission for medical treatment of their poisoning:

      Liaise with your on-call hospital based Mental Health Service before discharge (if available)

      Arrange ongoing support through a local mental health service e.g.

    • Headspace National Youth Mental Health Foundation (12-25 years old): Go to headspace.org.au and click “Find a centre”
    • Victorian Child and Adolescent Mental Health Services (CAMHS)  (0 – 18 years old): Go to health.vic.gov.au and search by region based on residential address

    Parent information

    Kids Health Info: Poisoning prevention for children Parent information

    Victorian Poisons Information Centre: The prevention of poisoning

    Last Updated October 2018