153. Inhaled toxins Flashcards
Definition of asphyxiant
any gas that displaces sufficient oxygen from the breathable air
5 asphyxiants
Carbon dioxide Nitrogen (scuba diving) Methane Helium (and other noble gases) Nitrous oxide (whipping cream cans)
Sx of asphyxiants
tachycardia, tachypnea, dyspnea, cerebral hypoxia
MGMT of asphyxiants
Remove from area
Supportive
Def. pulmonary irritants
gases that cause pulmonary irritation/inflammation after inhalation
Examples of irritants
Sulfur dioxide (smog from fossil fuels) Oxygen, hydrogen fluoride Chlorine from pools Smoke inhalation Tear gas Ammonia Phosgene
MGMT of irritants
- intubate for hoarseness or stridor
- treat bronchospasm
Describe the mechanism of cyanide toxicity
It is a cellular toxin – and inactivates cytochrome oxidase
The electron transport chain and inhibits oxidative phosphorylation / metabolism by binding to complex IV in the ETC.
This binding takes milliseconds, and the poisoned cells run out of ATP rapidly.
Leading to cellular hypoxia and death
List 4 methods of exposure to CN
Cyanide gas from fumigation
Gas from burning plastic/synthetic fibers
Cyanide salts (jewelry or photography industries) exposed to acidic conditions
Released in vivo from apricot pits or other prunus species pits (plums, cherries, nectarines, peaches).
KGB/spies assassinations
Hx and PHx for CN
CNS: Mild vague cns symptoms Coma Seizures Can develop persistent or delayed neurologic-psychiatric syndromes similar to CO or sulfur poisoning
CV: Chest pain Hypotension Bradycardia Dysrhythmias Cardiac arrest / shock
Lab finding in CN
Profound lactic acidosis Lactate > 10 mmol/L
ABG will show metabolic acidosis with an AG
Elevated mixed venous O2 saturation (cellular utilization of O2 is blocked)
“Arterialization of the venous blood”
Shortened QT interval
Normal pulse oximeter reading – despite cellular hypoxia
List 4 specific antidotal therapeutic options for CN toxicity
1) trifecta of pimping:
Amyl nitrite, sodium nitrite, sodium thiosulfate
2) hydroxocobalamin (Cyanokit) – IM / IV
List 3 situations when Lily kit may be contraindicated
Concomitant smoke inhalation in fire victims
Nitrite induces methemoglobinemia which further reduces tissue oxygen delivery
Patient in hypotensive, shock where further hypoxemia and hypotension would cause harm
inability to administer the inhaled amyl nitrite safely (risk of exposure to health care workers
4 Mechanisms of CO toxicity
1) CO interacts with deoxyhemoglobin to form COHb – which CANNOT CARRY OXYGEN.
2) In the muscle, CO binds myoglobin, which is what leads to atraumatic rhabdomyolysis.
3) CO affects oxygen use in tissues – by inhibiting cytochrome oxidase IV – similar to cyanide
4) Delayed onset neurologic complications – due to reperfusion injury, lipid peroxidation, alteration of the platelet-associated nitric oxide cycle;
loss of consciousness is a huge risk factor for developing delayed neuro. injury*
2 RFs for delayed neuro Sx
Older age
Loss of consciousness
