Medical Aspects of Chemical Warfare (2008) - The Black Vault

Medical Aspects of Chemical WarfareTable 21-9Variation of Sodium Nitrite and Sodium Thiosulfate Dose withHemoglobin ConcentrationInitial IntravenousInitial Intravenous DoseHemoglobin (g/dL) Dose of Sodium Nitrite 3% (mL/kg)* of Sodium Thiosulfate 25% (mL/kg) †7 0.19 0.958 0.22 1.109 0.25 1.2510 0.27 1.3511 0.3 1.5012 0.33 1.6513 0.36 1.8014 0.39 1.95*Not to exceed 10 mL total dose† Not to exceed 50 mL total doseData sources: (1) Cyanide antidote [package insert]. Buffalo Grove, Ill: Taylor Pharmaceuticals; 1998. (2) Berlin CM. The treatment of cyanidepoisoning in children. Pediatrics. 1970;46:793–796. (3) Hall AH, Rumack BH. Clinical toxicology of cyanide. Ann Emerg Med. 1986;15:1067–1074.iron from ferrous iron to ferric iron, changing thehemoglobin into methemoglobin. 96,97,102,103 Cyanide ismore strongly drawn to methemoglobin than to thecytochrome oxidase of cells, effectively pulling thecyanide off the cells and onto the methemoglobin. 97,103Once bound with the cyanide, the methemoglobinbecomes cyanmethemoglobin. 102 Therapy with nitritesalone is ineffective because methemoglobincannot transport oxygen in the blood. Adult dosescan potentially cause a fatal methemoglobinemia inchildren 103 or may cause profound hypotension. 96Treatment for children intoxicated by cyanide mustbe individualized and is based on the child’s bodyweight and hemoglobin concentration. 96,102,104 Anampule of amyl nitrite should be broken into a handkerchiefand the contents should be held in front ofthe patient’s mouth for 15 seconds, followed by 15seconds of rest. 102 This should be repeated only untilsodium nitrite can be administered; continuous useof amyl nitrite may prevent adequate oxygenation. 102Taylor Pharmaceuticals, the manufacturer of the kit,recommends a sodium nitrite dose of 6 to 8 mL/m 2(approximately 0.2 mL/kg body weight) for children,not to exceed the adult dose of 10 mL of a 3% solution(approximately 300 mg). 102 While excessive sodiumnitrite can cause methemoglobinemia, it should benoted that in the 70-year history of using the kit, theonly reported fatality of methemoglobinemia from itsuse involved a child without serious cyanide poisoningwho was given two adult doses of sodium nitrite. 103,104The scientific literature recommends pediatric dosingbased on monitoring hemoglobin levels. 103,104The next step in the cyanide antidote kit is to administersodium thiosulfate intravenously. 96,97,102,104 Thesodium thiosulfate and cyanmethemoglobin becomethiocyanate and release the hemoglobin, and the thiocyanateis excreted by the kidneys. Hemoglobin levelsshould be continuously monitored while administeringsafe doses of sodium nitrite and sodium thiosulfate (Table21-9). 102–104 If, after inquiring about a patient’s medicalhistory, a healthcare provider is concerned aboutanemia in a patient, doses should be decreased. 96,103,104Methemoglobin levels must be monitored sequentiallyin children and should not exceed 20%. 96Alternative Strategies. Alternative methodsof treating cyanide intoxication are used in othercountries. For example, the method in France useshydroxycobalamin (a form of vitamin B 12), which combineswith cyanide to form the harmless vitamin B 12acyanocobalamin. 96,97 On December 15, 2006, the FDAapproved hydroxocobalamin for use in the UnitedStates to treat cyanide-exposed victims in a productcalled the “Cyanokit” (EMD Pharmaceuticals Inc,Durham, NC; see Chapter 11, Cyanide Poisoning).Decontaminating CHILDRENDecontamination after a chemical terrorist attackneeds to be well-planned, efficient, and cognizant ofchildren’s special needs. Children’s unique vulnerabilitiesmay lead to a disproportionate number ofpediatric victims after a chemical attack. The potentialfor a high number of preventable pediatric casualties676