Synonym: Toxic asphyxiation
Category: Occupational
Agent Type: Chemical
Acuity: Acute-Severe
Latency/Incubation: Seconds
Initial Symptoms: Lightheadedness and headache; syncope
may be the initial symptom in an atmosphere with high concentration of
asphyxiant;
Comments: Chemical asphyxiants include hydrogen cyanide (HCN), hydrogen sulfide (H2S), and carbon monoxide (CO). HCN and H2S combine with mitochondrial cytochrome oxidase to disrupt respiration at the cellular level, while CO binds with hemoglobin to block the delivery of oxygen to the cells. Other findings may include confusion, ataxia, weakness, and tachycardia that can progress to bradycardia and asystole.
[5MCC-2006, Current
Consult, p. 1078, 1091, Ford, p. 706]
Hydrogen cyanide (AC) and cyanogen chloride (CK) are chemical weapons with limited usefulness on the battlefield. They are volatile substances, and relatively high concentrations are necessary to cause casualties. Following exposure, victims experience tachypnea, tachycardia, loss of consciousness, seizures, and apnea. Recovery is likely if victims are immediately removed from exposure. Survival after 10-20 times the lethal dose is possible if specific antidotes (nitrites and sodium thiosulfate) as well as oxygen and good supportive care are available.
[USAMRICD, p. 36-55] Pulse oximetry cannot distinguish oxyhemoglobin from carboxyhemoglobin, and SpO2 is falsely elevated in CO poisoning.
[Merck Manual, p. 370] Cyanosis is usually absent in CO poisoning because carboxyhemoglobin is bright red. However, a cherry red skin color is a post-mortem finding. In patients poisoned by cyanide and azide, cyanosis is usually absent because the hemoglobin is oxygenated but is not utilized. Methemoglobinemia is another form of chemical asphyxiation. Hyperbaric oxygen is indicated for pregnant women with significant CO poisoning.
[AHLS, p. 100, 223] See "Methemoglobinemia."
Diagnostic: History; signs of brain hypoxia;
carboxyhemoglobin level;
Signs & Symptoms: dizziness; syncope; arrhythmia;
bradycardia; tachycardia; nausea, vomiting; confusion; headache;
incoordination; seizure; weakness; dyspnea, acute; stupor and coma;
Syndromes: Acute Neurological, No Fever
Entry: Inhale
High-Risk Activities: Enter a farm silo 1-10 days after
filling; Enter sewer, manure pit, or ship hold; Operate internal combustion
engines; Use sodium cyanide to recover silver; Work with toxic
chemicals--spilled
Warfare: Victim--air release of chemicals/toxins;
