PPW4 Gases Flashcards
What is the mechanism of toxicity of carbon monoxide?
It binds to hemoglobin with an affinity over 200 times that of oxygen and produces carboxyhemoglobin, which is ineffective in oxygen delivery to tissues. It also binds to myoglobin with affinity 60 times that of oxygen. It also binds to cytochrome oxidase with less affinity than oxygen, so it is possible that it requires significant intracellular hypoxia before binding. This interferes with aerobic metabolism and adenosine triphosphate synthesis. Cells respond by switching to anaerobic metabolism, causing anoxia, lactic acidosis and eventually cell death
What are the symptoms of carbon monoxide poisoning?
Symptoms are similar to hypoxia
Toxicity of CO in pregnancy?
CO can cross the placenta, and have more affinity for fetal hemoglobin than adult one, and may cause severe fetal adverse effects
Diagnosis of CO poisoning?
Puls oximeter is not useful as it is unable to differentiate oxyhemoglobin from carboxyhemoglobin, so we rather use CO-oximeter.
What is the main treatment of CO poisoning?
Oxygen therapy with high oxygen concentration
What is the mechanism of toxicity of hydrogen sulfide?
It is a mucous membrane and respiratory tract irritant, that may lead to pulmonary edema and even unconsciousness and death if inhaled. Eye contact may lead to painful dermatitis and burring eyes.
When to suspect hydrogen sulfide poisoning?
- Rapid loss of consciousness (knocked down)
- Rotten egg odor
- Rescue from enclosed space such as sewer or manure pit
- Multiple victim with sudden death syndrome
- Collapse of a previously healthy worker at work site
Treatment of hydrogen sulfide poisoning?
Administer 100% oxygen and give sodium nitrite (which is the antidote)
What are the routes of exposure to cyanide?
Inhalation (smoke from a house), ingestion and skin exposure
What is the mechanism of toxicity of cyanide?
It inhibits cytochrome c oxidase and by attaching to the iron within this protein, which prevents transport of electrons from cytochrome c to oxygen and thus the cell can no longer produce ATP.
When should you suspect cyanide?
- Sudden collapse of laboratory or industrial worker
- Fire victim with coma
- Ingestion of artificial nail remover
- Ingestion of seeds or pits from prunus species
- Patient with altered mental status, academia and tachyphylaxis to nitroprusside
What are the antidotes for cyanide poisoning?
Hydroxycobalamin and cyanide antidote kit
