2008-04-15_REVISION - M1980244 (345)

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FIRST AID MEASURES(continued) • Antidotal Effects Section) If symptoms persist or recur after the initial treatment, repeat the antidote at one half the original doses one hour after the original administration. Monitor methemoglobin levels when practical in every patient treated with the intravenous antidote. AVOID OVER-TREATMENT. The above sodium nitrite injection discussed in the Medical Treatment Procedure Section is about one-third the lethal dose, so care should be taken to avoid excessive use. It is not essential that full quantities of antidote be given just because treatment was started. Should injection be stopped fior any reason, keep track of the amount administered in case treatment needs to be restarted. ANTIDOTAL EFFECTS Nitrites can produce hypotension through peripheral vasodilatation (widening of the blood vessels). Methemoglobin formation, although considered a therapeutic effect, may cause symptoms ifi levels exceed 20-30%. Recommended intravenous doses of sodium nitrite discussed in the Medical Treatment Procedure Section usually produce methemoglobin levels under 20%. Headache, nausea, vomiting, and syncope (f ainting) may follow nitrite administration, and syncope may occur if the patient is not lying down. While it is important to be aware of the effects firom nitrite therapy, there have been no long-lasting efifiects associated with this treatment regimen fior cyanide exposure in DuPont's experience and knowledge. RECOVERY AND DISPOSITION For most accidental poisonings, patients can be revived in a fi ew minutes using oxygen and amyl nitrite with complete recovery within a few hours. If necessary, the patient should be monitored fior 24-48 hours. Any patient whose symptoms require the use ofi IV antidote should be considered for admittance to an intensive care unit. Observe for return of symptoms. Monitor methemoglobin levels, blood pH and oxygenation through arterial blood gas analysis. Calculate anion gap from serum electrolytes. Cyanide poisoning causes lactate accumulation and an anion gap metabolic acidosis. Delayed neurotoxic effects are not expected consequences of cyanide exposure although neurotoxic effects may occur if hypoxia (oxygen deficiency) was prolonged or occurred following massive cyanide exposure. In the presence ofi smoke inhalation that can occur during fires, withholding amyl nitrite or sodium nitrite administration should be considered because ofi the potential for high carboxyhemoglobin levels. However, administration of oxygen and possibly sodium thiosulfiate should be continued. (Continued) 1252CR Page 9