Detecting cyanide exposure based on thiocyanate measurement in saliva
Inventors
Reed, David A. • Emmett, George C.
Assignees
US Department of Homeland Security
Publication Number
US-12023174-B2
Publication Date
2024-07-02
Expiration Date
2041-04-30
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Abstract
In an example, a method of detecting cyanide exposure of an individual includes: measuring a thiocyanate level of the individual which includes placing saliva of the individual in contact with a chemical indicator to measure the thiocyanate level and measuring thiocyanate (SCN−) catalyzed by enzyme rhodanese of the individual; 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 cyanide poisoning for which a medical procedure is recommended to manage health effects of the exposure; and performing the medical procedure if the measured thiocyanate level is above the preset thiocyanate threshold and not performing the medical procedure if the measured thiocyanate level is not above the preset thiocyanate threshold.
Core Innovation
The invention discloses a method and system for detecting cyanide exposure in an individual by measuring the level of thiocyanate in saliva, which is formed as a detoxification response to cyanide exposure catalyzed by the enzyme rhodanese. The measurement involves placing the individual's saliva in contact with a chemical indicator such as a colorimetric indicator (e.g., iron nitrate) to determine the thiocyanate level. The measured thiocyanate level is compared to a preset threshold to assess whether it indicates acute cyanide poisoning requiring medical treatment.
The disclosure also includes additional measurements of methemoglobin and carboxyhemoglobin levels to improve reliability. A depressed methemoglobin level below a preset threshold combined with an elevated thiocyanate level above a threshold provides a more reliable indication that the body's cyanide detoxification mechanisms are overwhelmed, warranting medical intervention. Similarly, measuring an elevated carboxyhemoglobin level alongside thiocyanate aids in assessing combined cyanide and carbon monoxide poisoning risks.
The problem being solved is the difficulty in quickly and affordably diagnosing cyanide exposure in individuals, particularly in scenarios such as fire smoke inhalation, where cyanide is a lethal hazard. Existing detection methods for cyanide exposure are not widely available, rapid, or confirmatory. The invention provides a fast, on-scene test that allows firefighters and medical personnel to determine cyanide intoxication quickly and reliably for timely medical treatment, overcoming issues related to reliance on clinical signs, symptoms, or expensive tests.
Claims Coverage
The patent includes three independent claims focusing on methods for detecting cyanide exposure by measuring thiocyanate in saliva combined with either carboxyhemoglobin or methemoglobin levels.
Detecting cyanide and carbon monoxide exposure by measuring thiocyanate and carboxyhemoglobin levels
The method includes measuring thiocyanate level of an individual by contacting saliva with a chemical indicator, measuring carboxyhemoglobin level to assess CO exposure, and comparing both levels against preset thresholds to determine poisoning levels. A medical procedure is recommended and performed if both levels exceed their thresholds.
Detecting cyanide exposure by measuring thiocyanate and methemoglobin levels
The method involves measuring thiocyanate level in saliva and methemoglobin level in an individual, comparing these levels to preset thresholds to determine cyanide poisoning. Medical treatment is administered if thiocyanate is above and methemoglobin is below their respective thresholds.
Cyanide exposure detection with sequential or combined measurements of thiocyanate, methemoglobin, and carboxyhemoglobin
The method includes measuring thiocyanate level to check against a high threshold, and if below that, measuring methemoglobin level and comparing with a lower thiocyanate threshold and methemoglobin threshold. If criteria are met, medical treatment is recommended. Otherwise, carboxyhemoglobin level is measured and combined with a third thiocyanate threshold to determine if treatment is needed, covering exposures involving cyanide and carbon monoxide.
The independent claims collectively cover methods of detecting cyanide exposure by quantitatively measuring thiocyanate in saliva using a chemical indicator and threshold comparison, optionally combined with methemoglobin and carboxyhemoglobin level measurements to improve detection accuracy and medical decision-making.
Stated Advantages
Provides a fast, on-scene, affordable test for presumptively identifying dangerous cyanide exposure levels.
Enables timely medical intervention by allowing health responders to rapidly detect cyanide poisoning.
Improves reliability of cyanide exposure detection by combining thiocyanate measurements with methemoglobin and carboxyhemoglobin levels.
Reduces reliance on clinical signs and symptoms, which can be misleading due to overlap with carbon monoxide poisoning.
Permits non-invasive sampling through saliva, facilitating ease of testing under field conditions.
Enables identification of cyanide exposure in fire smoke victims quickly to improve survival outcomes.
Documented Applications
Rapid on-site detection of cyanide intoxication in firefighters exposed to smoke inhalation.
Screening fire smoke victims for dangerous cyanide exposure levels to determine the need for medical treatment.
Monitoring individuals repeatedly exposed to cyanide to assess exposure levels over time through saliva testing.
Field deployment for front-line detection of cyanide exposure using low-cost test devices with colorimetric indicators.
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