Cyanide Poisoning

Question 1

Cyanide Patho

Answer 1

Binds with high affinity to ferric ion cytochrome a3 (electron transport chain) and therefore stops ATP production regardless of O2. Tissues with high oxygen demand are affected first

Question 2

Sources of cyanide

Answer 2

Burning, fumigants and fertilizers, vermin exterminations, chemistry laboratories, some plant seeds (cassava, bamboo, apricots, cherries, plums, peaches) dartskies and vehicle exhause

Question 3

Smokers, cyanide and excretion

Answer 3

2.5X higher in smokers

Detox is metabolism in liver by rhodanese to thiocyanate which is renally excreted

Question 4

Low exposure symptoms (less than 50ppm)

Answer 4

Anxiety, palpitations, dyspnea and headache

Question 5

Higher concentrations of cyanide symptoms

Answer 5

Severe dyspnea, coma, seizures, dysrhythmias.

Question 6

Lethal dose of cyanide gas

Answer 6

200ppm for 30 minutes and 600-700 for 5.
Symptom onset is within minutes
K+ or Na+ cyanide 140-250mg, but as little as 50 can kill a person

Question 7

Typical cyanide presentation

Answer 7

Altered LOC, hyperventilating, hypotensive, bradycardic and a smell of bitter almonds (only 60-80% can detect)

Question 8

Delayed cyanide poisoning

Answer 8

Acetronitrile (cosmetic nail remover) and amygdalin from apricot pits slowly release cyanide (delayed onset of symptoms?)

Question 9

Lab results cyanide poisoning

Answer 9

Elevated anion gap - lactic acidosis from anaerobic metabolism
Metabolic acidosis
Lactate <90mg/dL
Normal O2 sats
Decreased arterial mixed venous oxygen difference - decreased tissue O2 consumption
Whole blood cyanide >0.5mcg/mL Fatal at >2.5 (plasma is 1/10th of whole blood)

Question 10

TX for cyanide

Answer 10

100% O2
fluid/vasopressors hypotension
Bicarb for acidosis (enhances nitrites and thiosulfate)
Amyl nitrite, 3% sodium nitrite, and 25% sodium thiosulfate
Consult with expert for these

Question 11

Nitrites physiology

Answer 11

Create methemoglobin, which bind cyanide better than ferric iron of cytochrome oxidase.
Hypotension may occur but is not a contraindication
Pts who also have CO poisoning may suffer as methemoglobin means less hemoglobin for O2 to bind to

Question 12

Methemglobin

Answer 12

Iron is Fe3+ instead of normal Fe2+ of hemoglobin

Question 13

Sodium Thiosulfate

Answer 13

Enhances rhodanese which catalyzes transfer of sulfate from sodium thiosulfate to cyanide to form thiocyanate (less toxic, excreted by kidneys)
CAN be used if pts have CO poisoning

Question 14

Hydroxocobalamin

Answer 14

Cobolt center that binds cyanide and forms cyanocobalamin
Good for when its unknown if it is cyanide, or if theres also CO on board.
Dose is 5G IV over 15 minutes and a second dose of 5g may be repeated.

Question 15

Hydroxocobalamin sides

Answer 15

transient HTN, reddish discolouration of skin and mucous membranes, rarely anaphylatic reactions

Question 16

Dimethylaminophenol

Answer 16

Rapidly induces methemglobin. Similar efficiency to sodium nitrite. 250mg IV over 1 minute used with sodium thiosulfate

Question 17

Dicobalt edetate

Answer 17

Cobalt compound with high affinity for cyanide. Toxic when cyanide is not present.
300mg IV over 1 minute, repeat after 5 minutes

Question 18

Cobinamide

Answer 18

Precursor to cobalamine, highly effective. Can be given IM

Question 19

Gastic decontamination

Answer 19

For pts who are alert, have a patent airway, and present within 1 hour of ingestion

Question 20

What is cyanide

Answer 20

Any chemical compound that contains a cyano group

Question 21

Where is cyanide found

Answer 21

Acrylic fibers, synthetic rubber and plastics, mining gold and plata, pigment in blueprints and blue jeans. Burning unleashes their cyanidy fury!

Question 22

Burning these produces cyanide

Answer 22

Wool, nylon, silk, acrylic, polyurethane, other plastics. Suspect cyanide in any pt exposed to combustion

Question 23

Hydroxocobalamin dosing

Answer 23

5G
SIVP for seizures or arrest
over 15 minutes if not
Second dose OLMC 15 minutes - 2 hours
May interefere with pulse ox and CO ox readings
Don’t mix with other meds (use second line if you can)