Ver el código de «Cyanide toxicity»

==Background==
*Sources
**Burning of nitrogen-containing polymers (plastics, wool, silk)
**Prolonged use of nitroprusside
**Pits of peaches, pears, apricots, crab apples
*Pathophysiology
**Binds to cytochrome oxidase in mitochondria; leads to cessation of electron transport
***Causes switch from aerobic to anaerobic metabolism despite adequate O2

==Clinical Features==
===Acute Intoxication===
*Affected by dose, route, formulation and exposure pattern
**Inhaled toxins more rapid than ingested
***Inhalation exposure may cause syncope and death after only a few breaths
*'''Early signs'''
**CNS stimulation (Headache, anxiety, confusion)
**Tachycardia, palpitations and hypertension
**Tachypnea
**Cherry-red color (rarely seen)
*'''Late signs'''
**Nausea, Vomiting
**Bradycardia, hypotension, arrhythmias, asystole
**Coma, Seizures (rare), Mydiriasis
**bradypnea and pulmonary edema (non-cardiogenic), apnea
**Renal Failure
**Hepatic Necrosis
**Cyanosis
**Rhabdo, bright red venules seen on fundoscopy

===Chronic===
*Retrobulbar Optic Atropy (proposed)
**Heavy smokers
*Ataxic peripheral neuropathy
*Konzo
**Spactic upper motor neuron paraparesis seen in chronic ingestion of inadequately cooked casava

==Diagnosis==
#Smell of bitter almonds (only 60-80% of population can detect this)
#Severe unexplained metabolic acidosis (lactic)
#PO2 of venous blood similar to arterial blood
#normal SpO2
#Cherry-red skin color is uncommon 

==Work-Up==
#Lactate
#VBG and ABG (narrowing of the venous-arterial PO2 gradient)
#Co-oximetry
#Chemistry (anion gap acidosis)

==Treatment==
#Supportive care
##O2 100% NRB
##IVF and vasopressors for hypotension
##Bicarb for acidemia (enchances of effect of nitrite and thiosulfate)
#Antidote

===Cyanokit (Hydroxocobalamin)===
1st line therapy
====Mechanism of action====
Directly binds CN forming cyanocobalamin which is readily excreted in the urine
====Administration====
#Give 70mg/kg IV over 15min (5g is standard adult dose); may repeat 5g once as needed
#Also give 25% Na thiosulfate  1.65ml/kg IV (12.5g max dose) over 10min; may repeat at 1/2 original dose if needed
====Adverse Effects====
#May cause temporary reddish discoloration of skin, plasma, urine, mucous membranes
#'''Interferes with colorimetric tests''' -- Pulse ox, Hemoglobin, Carboyxhemoglobin, methemeglobin, oxyhemoglobin, Serum Cr, AST/ALT, bilirubin, magnesium for 2-3 days
;OBTAIN Co-ox and labs prior to Hydroxocobalamin administration

===Cyanide Antidote Package===
#2nd line therapy - use if Cyanokit unavailable
#Consider using only Na thiosulfate (no nitrites) in cases where concern for CO poisoning
#Mechanism of action
##Nitrites: form metHb which binds CN more avidly than cytochrome oxidase
##Thiosulfate: donates its sulfur group to CN to form thiocyanate (less toxic than CN)
#Warnings
##Nitrites are relatively contraindicated in pts w/ concomitant CO toxicity
###Induction of metHb further exacerbates O2 delivery
##Avoid nitrites in presence of severe hypotension if diagnosis is unclear
#How to use:
##Amyl nitrite inhaled by pt (only use if unavailable to obtain IV)
###Hold under pt's nose for 30s of each minute, for 3 minutes
##Sodium nitrite 10 mg/kg IV over 5min (use instead of amyl nitrite if IV is available)
###Lack of measurable MetHb levels after administration confirms CN presence
###Monitor MetHb and keep level <30%
###Peds requires dosing based on Hb (see Peds dosing below)
##Sodium thiosulfate 12.5g over 10min; may repeat at 1/2 original dose if needed

===Sodium Nitrite (Peds Dosing)===
*Max dose should not exceed 10mL
*Do not give faster than 5mL/min (to avoid hypotension)
#Hb 7 g/dL, dose is 0.19 mL/kg of 3% sodium nitrite
#Hb 8 g/dL, dose is 0.22 mL/kg of 3% sodium nitrite
#Hb 9 g/dL, dose is 0.25 mL/kg of 3% sodium nitrite
#Hb 10 g/dL, dose is 0.27 mL/kg of 3% sodium nitrite
#Hb 11 g/dL, dose is 0.30 mL/kg of 3% sodium nitrite
#Hb 12 g/dL, dose is 0.33 mL/kg of 3% sodium nitrite
#Hb 13 g/dL, dose is 0.36 mL/kg of 3% sodium nitrite
#Hb 14 g/dL, dose is 0.39 mL/kg of 3% sodium nitrite

==Disposition==
#Admit all pts for obs

==See Also==
*[[Carbon Monoxide (CO)]]
*[[Hydrogen Sulfide]]
*[[Burns]]
*[[Acrylonitrile]]

==Source==
*Tintinalli
*UpToDate

[[Category:Tox]]