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RUSVM Toxicology > Toxic Gases 1 > Flashcards

Toxic Gases 1 Flashcards

1
Q

How are animals usually exposed to ammonia (NH3) ?

A

Inhalation
Burning plastic/nylon
Agricultural fertilizer

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2
Q

What are the properties of ammonia?

A

Sharp odor (olfactory accommodation)
Heavier than water
Soluble in water

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3
Q

What is the MOA of ammonia?

A

Reacts with hydroxyl ions —> ammonia hydroxide —> irritant and caustic (dermal and mucosal )

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4
Q

What effect does ammonia have on the respiratory system?

A

Disrupt cell integrity —> increased permeability of lung capillaries —> edema and congestion

Inflammation/irritation —> susceptibility to secondary infections

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5
Q

Death due to ammonia gas results from?

A

Asphyxia, and partly due to electrolyte and cellular metabolic effects

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6
Q

Humans can detect ammonia at ________ppm in the air, and their eyes burn at ______ppm

A

10; 25-35

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7
Q

Where are high concentrations of ammonia usually found and who is must suspecptible

A

Animal houses

-livestock: swine and poultry

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8
Q

What are the acute signs of ammonia toxicity?

A 
Red mucous membranes
Lacrimation 
Coughing 
Sneezing 
Nasal discharge
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9
Q

What are the chronic clinical signs of ammonia toxicity?

A

Decreased growth rate, decreased egg production in birds

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10
Q

What are the terminal signs of ammonia toxicity?

A

Cyanosis, CNS stimulation, and clonic convulsions

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11
Q

How can you make a diagnosis of ammonia toxicity?

A

History
Clinical signs
Lesions and the odor of ammonia make diagnosis obvious

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12
Q

What is your DDX for inhaled irritants causing respiratory insufficiency?

A 
Hydrogen sulfide 
Nitrogen oxide 
Sulfur oxide
Fumes
Dusts
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13
Q

How do you treat ammonia toxicity?

A 
Removal of NH3 source 
Ventilation 
Fresh air for dyspnea 
Soothing ointment for eyes
Antibiotics for secondary infection 
Diuretic for edema
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14
Q

What is usually the source of exposure to hydrogen sulfide?

A

Waste pits/manure packs/sewage

  • normal levels 10ppm
  • agitated —> deadly at 100ppm
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15
Q

What are the properties of hydrogen sulfide?

A

Colourless and odor of rotten eggs
Heavier than air
Flammable

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16
Q

What is the MOA of hydrogen sulfide?

A

Converted to sulfuric acid in solution and forms sodium sulfide when contacts moist mucus membranes —> irritant

Inhibit cellular respiration by inhibition cytochrome oxidase

Stimulate carotid body chemoreceptor —> depress respiratory drive

Reacts with silver, iron, lead, and other metals —> dark or black coloured compounds in GI tract

17
Q

what is the most dangerous sewage gas?

A

Hydrogen sulfide

18
Q

Where is hydrogen sulfide absorbed, metabolized, and excreted?

A

Absorbed in lungs and GI tract

Converted to alkali sulfides in blood —> oxidized to sulfate and is excreted in urine

Some sulfide excreted in feces as iron sulfide (dark/blood appearance )

19
Q

What are the acute clinical signs of hydrogen sulfide?

A

Large concentrations
Sudden collapse, cyanosis, dyspnea, anoxic convulsions

Rapid death

20
Q

What are the chronic clinical signs of hydrogen sulfide?

A

Lower concentrations

Irritation to ocular, respiratory mucosa, and lungs

21
Q

What lesions do you see in hydrogen sulfide toxicity?

A

Blood is dark and may not clot
Tissue dark/greenish purple

Odor of H2S
GI contents dark and odorous

22
Q

How do you treat hydrogen sulfide toxicity?

A

Remove source

Sodium nitrate IV - forms methemoglobin that binds radicals and reactive cytochrome oxidase

Oxygen, ventilation, and supportive care

23
Q

What are the sources of exposure of CO?

A

Fires, space heater, engines in confined spaces

24
Q

What are the properties of CO

A

Odorless and colourless

NOT water soluble —> not an irritant like the other gases

25
Q

CO > __________ppm can cause clinical signs and death in 1hr

A

1000 (0.1%)

26
Q

What is the MOA of CO ?

A

Combines with hemoglobin to form carboxyhemoglobin (COHb) which cannot carry oxygen and interferes with O2 release

—> anoxemia/hypoxia
—> interfere with cellular respiration

27
Q

What are the clinical signs associated with CO?

A

Low exposure (30-60%) - hypoxia, drowsiness, incoordination, dyspnea, lethargy, coma

High expire (60-70%). - death

28
Q

Moderate concentrations (<250ppm) of CO can have what affect on lambing/farrowing?

A

Increase number of stillborn fetuses

29
Q

What are the lesions seen in CO toxicity?

A

Blood is bright red and the mucous membranes are healthy pink

Chronic- brain edema, hemorrhage, and necrosis

30
Q

How can you diagnose CO toxicity in the lab?

A

Measure CO in air
Measure % of carboxyhemoglobin in the blood or in fetal thoracic fluid

first gas that has a laboratory diagnosis

31
Q

How do you treat CO toxicity?

A

Oxygen or 5%CO2 in oxygen administered with positive pressure
Blood transfusion

Recovery may or may not occur

RUSVM Toxicology (23 decks)

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