Key investigations

Key investigations for cyanide poisoning are:

• blood lactate concentration—more than 10 mmol/L in severe poisoning
• serum electrolyte, urea and creatinine concentrations
• electrocardiogram (ECG)
• blood gas analysis—markers of impaired extraction of oxygen from the blood to the tissues are
  • high venous partial pressure of oxygen (PvO₂)
  • reduced arterial–venous oxygen saturation difference.

There is no laboratory test to confirm cyanide exposure.