Smoke inhalation victims (house fires) are at risk of carbon monoxide (CO) and cyanide poisoning (CN). CO exposure/poisoning can be readily evaluated by CO - Oximetry but CN level can be obtained in majority of the hospital.
Lactic acid level is often sent to evaluate for CN poisoning.
Bottom line:
Lactatic acid levels should be sent in all smoke inhalation victims.
Elevate lactate > 10 mmol/L is highly suggestive of CN poisoning .
Answer
In a manuscript published in 1991, N Engl J Med by Dr. FJ Baud is the source of this data.
CN blood levels were measured in 109 residetial fire victims in France prior to any treatment was initiated.
43 fire victims who died had mean blood CN level of 116.4 micromol/L
66 fire victims who survived had mean blood CN level of 21.6 micromol/L
Plasma lactate level correlated more closely with blood CN level than blood CO level.
Elevated lactate of 10 mmol/L was sensitive (87%) for CN level > 40 micromol/L (defined level of CN toxicity) with specificity of 94% and positive predictive value of 95%.
References
Baud FJ et al. Elevated blood cyanide concentrations in victims of smoke inhalation. N Engl J Med 1991;325:1761-6.
