System and method for detecting cyanide exposure
Inventors
Reed, David A. • Emmett, George C.
Assignees
US Department of Homeland Security
Publication Number
US-11272878-B2
Publication Date
2022-03-15
Expiration Date
2041-04-30
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Abstract
In an example, a method of detecting cyanide exposure of an individual comprises measuring a thiocyanate level of the individual, and comparing the measured thiocyanate level to a preset thiocyanate threshold to determine whether the measured thiocyanate level is above the preset thiocyanate threshold indicating a level of acute cyanide poisoning for which medical treatment is recommended to treat health effects of the exposure.
Core Innovation
The invention provides a method and system for detecting cyanide exposure in individuals by measuring a thiocyanate level and comparing it to a preset thiocyanate threshold. This comparison determines whether the individual has an acute level of cyanide poisoning that warrants medical treatment. The method relies on detecting elevated salivary thiocyanate, which results from the body's detoxification of cyanide, and in some embodiments, also considers methemoglobin and carboxyhemoglobin levels for further confirmation of poisoning.
The problem addressed is the difficulty in rapidly and reliably detecting cyanide poisoning, especially in fire victims and first responders exposed to smoke. Cyanide poisoning is hard to measure timely in exposed individuals, and clinical signs can be misleading due to similarities with carbon monoxide poisoning symptoms. The lack of widely available, affordable, and quick confirmatory tests for cyanide exposure impedes effective timely treatment, which is crucial for patient recovery.
The invention solves this by using a fast, on-scene, and affordable approach based on measuring thiocyanate, a stable metabolite of cyanide detoxification present in saliva at elevated levels after exposure. By combining this measurement with assessments of methemoglobin depletion or elevated carboxyhemoglobin, the invention provides a more reliable screening method for cyanide intoxication. This allows for earlier medical intervention and potentially improves survival outcomes for those exposed to toxic smoke.
Claims Coverage
The patent claims include multiple independent claims focusing on methods for detecting cyanide exposure, each providing inventive features around measuring and comparing thiocyanate and related blood parameters.
Measuring and comparing thiocyanate levels with a preset threshold to detect acute cyanide poisoning
A method comprising measuring an individual's thiocyanate level and comparing it to a preset threshold to determine whether the level indicates acute cyanide poisoning that requires medical treatment, where the threshold is determined through measuring thiocyanate in test individuals pre- and post-exposure and correlating with health effects.
Using chemical indicators with biological fluids to measure thiocyanate levels
Measuring thiocyanate by placing a biological fluid, such as saliva collected via swab or strip, in contact with a colorimetric chemical indicator (e.g., iron nitrate) to indicate thiocyanate concentration.
Combining thiocyanate and methemoglobin levels to enhance detection reliability
Measuring a methemoglobin level and comparing it to a preset threshold to ascertain if it is below the threshold occurring alongside elevated thiocyanate, providing further indication of cyanide poisoning than thiocyanate level alone.
Utilizing pulse oximetry for measuring methemoglobin and carboxyhemoglobin levels
Using pulse oximetry to measure methemoglobin and carboxyhemoglobin levels, where low methemoglobin and elevated carboxyhemoglobin combined with elevated thiocyanate indicate cyanide and carbon monoxide poisoning respectively.
Multi-threshold decision method for medical treatment recommendation
Measuring thiocyanate against a first preset threshold to recommend treatment if exceeded; if not, measuring methemoglobin and comparing to second, lower thiocyanate threshold and methemoglobin threshold for treatment recommendation; alternatively, measuring carboxyhemoglobin against a third, lower thiocyanate threshold and its own threshold to recommend treatment.
Determining preset thiocyanate threshold based on population studies
Establishing the preset threshold by measuring thiocyanate in unexposed and exposed test individuals, monitoring health outcomes, identifying harmed individuals, and comparing thiocyanate levels to determine a threshold above which medical treatment is recommended.
The claims cover inventive methods for detecting cyanide exposure through measuring thiocyanate levels compared to preset thresholds determined by population data, optionally combined with methemoglobin and carboxyhemoglobin measurements to enhance detection accuracy. The methods use colorimetric chemical indicators on biological fluids and pulse oximetry to identify acute poisoning and guide medical treatment decisions.
Stated Advantages
Provides a fast, on-scene, affordable, and reliable presumptive test for acute cyanide poisoning.
Enables earlier detection of cyanide exposure in fire victims and first responders to facilitate timely administration of antidotes.
Offers a non-invasive technique utilizing saliva samples and pulse oximetry, simplifying and expediting exposure assessment.
Combining thiocyanate with methemoglobin and carboxyhemoglobin measurements improves accuracy and reduces false positives.
Helps reduce fatalities and serious health effects by facilitating prompt medical treatment based on objective biochemical indicators.
Documented Applications
Screening firefighters and smoke inhalation victims on scene for dangerous levels of cyanide exposure.
Using saliva samples with colorimetric indicators and pulse oximetry for field detection of cyanide and carbon monoxide poisoning.
Establishing exposure thresholds through testing populations pre- and post-exposure to relate thiocyanate levels to health outcomes.
Deployment of test kits and devices for frontline emergency medical technicians to rapidly assess cyanide exposure and initiate treatment.
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