Report on a study of fires with smoke gas development : determination of blood cyanide levels, clinical signs and laboratory values in victims.

Background: This is a report on an international non-interventional study of patients exposed to fires with smoke development in closed rooms. The objective of the study was to document clinical symptoms, relevant laboratory values and blood cyanide concentrations from fire victims in order to confirm or rule out presumptive correlations between the individual parameters.

Materials And Methods: The study was conducted in five European countries with patients being included if they presented with the characteristic clinical signs, such as soot deposits and altered neurological status. Venous blood samples were taken from victims prior to administration of an antidote in all cases and determination of cyanide concentration was performed in a central laboratory using high performance liquid chromatography.

Results: Data from 102 patients (62 % male, average age 49 years) were included in the evaluation with no blood samples being available for analysis from 2 patients. In 25 patients the blood cyanide concentration was below the limit of detection of 1.2 μmol/l. Cyanide levels between 1.2 and 10 μmol/l were measured in 54 patients, 7 patients had values between 10 and 20 μmol/l, 4 patients between 20 and 40 μmol/l while levels above 40 μmol/l were determined in 10 patients. The results of the study could not demonstrate that the cyanide level was influenced either by the interval between smoke exposure and blood sampling or the duration presence at the fire scene. The following clinical signs or laboratory values were recorded as relevant for increased and possibly toxic cyanide levels: respiratory arrest, dyspnea, resuscitation requirement, tracheal intubation, respiratory support measures, low Glasgow coma scale (GCS) score and respiratory frequency. A correlation between cyanide concentration and the total amount of soot deposits on the face and neck, in the oral cavity and in expectoration was confirmed. A correlation between cyanide and carboxyhemoglobin (COHb) levels in the blood of fire victims was also confirmed.

Conclusions: As long as it is not possible to immediately determine the blood cyanide concentration in patients exposed to fire with smoke development, a decreased GCS score, soot deposits particularly in expectoration, dyspnea and convulsions are to be regarded as risk markers for intoxication. In their presence immediate administration of hydroxocobalamin as an antidote is recommended.