Toxic Gases Flashcards
List the toxic gases covered in this course!
ammonia, hydrogen sulfide, carbon monoxide, nitrogen oxide gases and sulfur oxide gases
Source of ammonia (NH3)?
decomposing manure in confined animal houses, burning nylon/plastics, anhydrous NH3 used in agriculture fertilizer
Properties of ammonia?
sharp odor, heavier than air, soluble in water and readily reacts with hydroxyl ions in moist mucous membranes to form ammonium hydroxide–irritant and caustic
Humans can detect about ____ ppm ammonia in air and their eyes burn at _____ ppm.
10; 25-35 ppm
Ammonia is most frequently found in high concentrations where?
animal houses–can reach 50 ppm
What species are most susceptible to ammonia gas toxicity?
livestock–swine, poultry
ADME of ammonia?
A=inhalation
D=to tissue cells
NH3 converted to strong irritant on MM
Exposure to _______ ppm can cause acute death.
5,000
MOA of ammonia toxicosis?
direct irritation of MM, increased susceptibility to resp infection, decreased growth in young, pulmonary edema and lung congestion, alkalosis and compensatory acidosis, inhibit TCA cycle
Cause of death d/t ammonia toxicosis?
asphyxia and partly d/t electrolyte and cellular metabolic effects
Clinical signs for ammonia toxicosis?
red MM, lacrimation, coughing, sneezing, nasal discharge, keeping eyes shut, decreased growth rate, decreased egg production, dyspnea
terminal signs: cyanosis, CNS stimulation, clonic convulsions
Lab diagnosis for ammonia toxicosis?
chem analysis not routinely made w/ toxic gases
Differential diagnosis for ammonia toxicosis?
dzs that cause resp insufficiency–> inhaled irritants (hydrogen sulfide, nitrogen, oxides, sulfur oxides, fumes, dusts, vapors), organophosphates, polychlorinated biphenyls, cardiac glycosides
Treatment for ammonia toxicosis?
remove source of NH3, animal premises kept clean and well ventilated, fresh air for dyspnea, soothing ointments applied to the eyes and ABs to prevent secondary infections, diuretics for pulmonary edema, tx secondary infections (pneumonia)
Source of hydrogen sulfide (H2S)?
decomposition of urine/feces in underfloor waste pits, deep litter, manure packs, sewage and other organic matter containing sulfur. by-product or waste material from industry. may be liberated in coal pits, gas wells or sulfur springs.
Name some gases liberated from the decomposition of urine and feces?
hydrogen sulfide, ammonia, carbon dioxide and methane
Properties of hydrogen sulfide?
colorless, odor of rotten eggs, heavier than air, irritant (converted to sulfuric acid in solution and forms sodium sulfide on contact w/ moist MM)
Hydrogen sulfide reacts with what in the GIT and maybe tissues to form black or dark-colored compounds?
silver, iron, lead and other metals
T/F Hydrogen sulfide is the second most dangerous sewage gas.
FALSE! It is the most dangerous!
Humans can detect hydrogen sulfide in air at ______ ppm.
0.025 ppm
Symptoms at different ppms of hydrogen sulfide.
20 ppm–> ocular irritation
50 ppm–> severe symptoms
200 ppm–> olfactory accommodation (Danger!)
400 ppm–> sudden exposure can be quickly fatal
1000 ppm–> rapid unconsciousness and death in 1 hr
T/F Acute hydrogen sulfide poisoning is directly responsible for more deaths in closed animal facilities than any other gases.
TRUE
ADME of hydrogen sulfide?
A=lungs and GIT
M=converted to alkali sulfides in blood, some sulfide trapped by natural disulfides such as glutathione in blood
E=feces as iron sulfide and urine as sulfate
MOA of hydrogen sulfide toxicosis?
direct irritation of MM, inhibition of cellular respiration by inhibiting cytochrome oxidate–can lead to permanent effects on NS, stimulation of chemoreceptors of the carotid body interfering with respiratory drive
What are the effects of stimulating the chemoreceptors of the carotid body?
causes hyperpnea–depletion of CO2–apnea–either recover or die from asphyxiation
Clinical signs of larger concentrations of hydrogen sulfide?
sudden collapse, cyanosis, dyspnea, anoxic convulsions and rapid death
Clinical signs of smaller concentrations of hydrogen sulfide?
signs of irritation to ocular, respiratory mucosa and lungs (like ammonia)
Lesions seen with hydrogen sulfide toxicosis?
blood is dark and may not clot, tissues may be dark or greenish purple, carcass may have the odor of hydrogen sulfide (sewage), if ingested the GI contents may be black or dark gray w/ sewage odor
Differential diagnosis for hydrogen sulfide toxicosis?
Same as ammonia
Treatment for hydrogen sulfide toxicosis?
remove source, sodium nitrite IV, hydrated sulfide anion, oxygen therapy, ventilation, supportive tx