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| ==Background== | | {{#ask: [[Is DrugClass::Benzodiazepine]] | ?SeizureDose=Dose | ?BrandName=Trade Name}} |
| ===Sources===
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| *Burning of nitrogen-containing polymers (plastics, wool, silk)
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| *Prolonged use of nitroprusside
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| *Pits of peaches, pears, apricots, crab apples
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| *Intentional poisoning
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| ===Pathophysiology===
| | [[Scarlet_fever_1.2.jpg|thumb|"Slapped cheeks" and "white mustache" (circumoral pallor) typical of scarlet fever.]] |
| *Binds to cytochrome oxidase in mitochondria; leads to cessation of electron transport
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| **Causes switch from aerobic to anaerobic metabolism despite adequate O2
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| ===Paris Fire Brigade Protocol=== | | We heard you. '''Our native WikEM app is back!''' Download from your app store now ([http://apps.apple.com/us/app/wikem/id576405449 iOS] and [https://play.google.com/store/apps/details?id=wikem.chris Android]). |
| {{Paris Fire Brigade Protocol}}
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| ==Clinical Features==
| | [http://mediawiki.org MediaWiki] |
| ===Acute Intoxication===
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| *Affected by dose, route, formulation and exposure pattern
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| **Inhaled toxins more rapid than ingested
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| ***Inhalation exposure may cause syncope and death after only a few breaths
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| *'''Early signs'''
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| **CNS stimulation (Headache, anxiety, confusion)
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| **Tachycardia, palpitations and hypertension
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| **Tachypnea
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| **Cherry-red color (rarely seen)
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| *'''Late signs'''
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| **Nausea, Vomiting
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| **Bradycardia, hypotension, arrhythmias, asystole
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| **Coma, Seizures (rare), Mydiriasis
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| **bradypnea and pulmonary edema (non-cardiogenic), apnea
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| **Renal Failure
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| **Hepatic Necrosis
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| **Cyanosis
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| **Rhabdo, bright red venules seen on fundoscopy
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| ===Chronic===
| | [http://apps.apple.com App] |
| *Retrobulbar Optic Atropy (proposed)
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| **Heavy smokers
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| *Ataxic peripheral neuropathy
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| *Konzo
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| **Spactic upper motor neuron paraparesis seen in chronic ingestion of inadequately cooked casava
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| ==Differential Diagnosis==
| | [https://apps.apple.com App] |
| {{Chemical weapon DDX}}
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| ==Diagnosis==
| | [http://apps.apple.com/us/app/wikem/id576405449 iOS] |
| ===Work-Up===
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| *Lactate (normal lactate highly suggests another diagnosis)
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| *VBG and ABG (narrowing of the venous-arterial PO2 gradient, causes venous hyperoxemia/increased redness -- as does CO poisoning)
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| *Co-oximetry
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| *Chemistry (anion gap acidosis)
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| *RBC or Serum cyanide levels (unlikely to return in time to be clinically useful)
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| ===Evaluation===
| | [https://apps.apple.com/us/app/wikem/id576405449 https://play.google.com/store/apps/details?id=wikem.chris iOS] |
| *Smell of bitter almonds (only 60-80% of population can detect this)
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| *Severe unexplained metabolic acidosis (lactic)
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| *PO2 of venous blood similar to arterial blood
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| *normal SpO2
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| *Cherry-red skin color is uncommon
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| ==Treatment==
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| *Supportive care
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| **O2 100% NRB
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| **IVF and vasopressors for hypotension
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| **Bicarb for acidemia (enchances of effect of nitrite and thiosulfate)
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| *Antidote
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| ===Cyanokit (Hydroxocobalamin)<ref>Borron SW, Baud FJ, Mégarbane B, Bismuth C. Hydroxocobalamin for severe acute cyanide poisoning by ingestion or inhalation. Am J Emerg Med. Jun 2007;25(5):551-8.</ref><ref>Bebarta VS, Tanen DA, Lairet J, Dixon PS, Valtier S, Bush A. Hydroxocobalamin and sodium thiosulfate versus sodium nitrite and sodium thiosulfate in the treatment of acute cyanide toxicity in a swine (Sus scrofa) model. Ann Emerg Med. 2010;55(4):345-51. </ref>===
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| 1st line therapy
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| ====Mechanism of action====
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| Directly binds CN forming cyanocobalamin which is readily excreted in the urine
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| ====Administration====
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| *Give 70mg/kg IV over 15min (5g is standard adult dose); may repeat 5g once as needed
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| *Also give 25% Na thiosulfate 1.65ml/kg IV (12.5g max dose) over 10min; may repeat at 1/2 original dose if needed
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| ====Adverse Effects====
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| *May cause temporary reddish discoloration of skin, plasma, urine, mucous membranes
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| *'''Interferes with colorimetric tests''' -- Pulse ox, Hemoglobin, Carboyxhemoglobin, methemeglobin, oxyhemoglobin, Serum Cr, AST/ALT, bilirubin, magnesium for 2-3 days<ref>Lee J, Mukai D, Kreuter K, et al. Potential interference by hydroxocobalamin on co-oximetry hemoglobin measurements during cyanide and smoke inhalation treatments. Ann Emerg Med. 2007;49(6):802-805.</ref>
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| ;OBTAIN Co-ox and labs prior to Hydroxocobalamin administration
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| ===Cyanide Antidote Package (Lilly kit)===
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| Composed of two drugs( two nitrites and a thiosulfate). The nitrites convert the iron in hemoglobin from the ferrous to the ferric form, creating methemoglobinemia. The thiosulfate is a sulfate donor, which allows the enzyme rhodanese to convert the cyanide to a form that can be renally excreted.
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| *2nd line therapy - use if Cyanokit unavailable<ref>Hall AH, Saiers J, Baud F. Which cyanide antidote?. Crit Rev Toxicol. 2009;39(7):541-52.</ref>
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| *Consider using only Na thiosulfate (no nitrites) in cases where concern for CO poisoning since nitrate administration will severely decrease oxygen carrying capacity
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| ====Mechanism of action====
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| *Nitrites: form metHb which binds CN more avidly than cytochrome oxidase
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| **Thiosulfate: donates its sulfur group to CN to form thiocyanate (less toxic than CN)
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| ====Warnings====
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| *Nitrites are relatively contraindicated in pts w/ concomitant CO toxicity
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| *Induction of metHb further exacerbates O2 delivery
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| *Avoid nitrites in presence of severe hypotension if diagnosis is unclear
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| ====Administration====
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| ;Amyl nitrite
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| *Inhaled by pt (only use if unavailable to obtain IV)
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| *Hold under pt's nose for 30s of each minute, for 3 minutes
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| ;Sodium nitrite
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| *10 mg/kg IV over 5min (use instead of amyl nitrite if IV is available)
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| *Lack of measurable MetHb levels after administration confirms CN presence
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| *Monitor MetHb and keep level <30%
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| ;Pediatric dosing is based on Hemoblogin (see Peds dosing below)
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| ;25% Sodium thiosulfate
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| *1.65ml/kg IV (12.5g max dose) over 10min
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| *may repeat at 1/2 original dose if needed
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| ===Sodium Nitrite (Peds Dosing)===
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| *Max dose should not exceed 10mL
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| *Do not give faster than 5mL/min (to avoid hypotension)
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| *Hb 7 g/dL, dose is 0.19 mL/kg of 3% sodium nitrite
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| *Hb 8 g/dL, dose is 0.22 mL/kg of 3% sodium nitrite
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| *Hb 9 g/dL, dose is 0.25 mL/kg of 3% sodium nitrite
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| *Hb 10 g/dL, dose is 0.27 mL/kg of 3% sodium nitrite
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| *Hb 11 g/dL, dose is 0.30 mL/kg of 3% sodium nitrite
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| *Hb 12 g/dL, dose is 0.33 mL/kg of 3% sodium nitrite
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| *Hb 13 g/dL, dose is 0.36 mL/kg of 3% sodium nitrite
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| *Hb 14 g/dL, dose is 0.39 mL/kg of 3% sodium nitrite
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| ==Disposition==
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| *Admit all patients for observation
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| ==See Also==
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| *[[Carbon Monoxide (CO)]]
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| *[[Hydrogen Sulfide]]
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| *[[Burns]]
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| *[[Acrylonitrile]]
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| ==References==
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| <references/>
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| ==Video==
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| {{#widget:YouTube|id=vsA6_c-cbe4}}
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| [[Category:Tox]]
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