Toxic Gases 2

Question 1

What is usually the source of nitrogen oxide gas toxicity?

Answer 1

Incomplete reduction of nitrates during the fermentation process in silos (AKA silos fillers disease)

Also a major pollutant in fossil fuel burning

Question 2

What colour are NO2 and N2O4 gases?

Answer 2

NO4 - reddish brown
N2O4- colourless

When mixed —> yellow brown

Question 3

What happens when nitrogen oxide gases come in contact with mucous membranes?

Answer 3

Gases form nitric acid (HNO3) and nitric oxide (NO)

Question 4

What odor does nitrogen oxide gases have?

Answer 4

Irritating chlorine like odor

Question 5

At what level are humans able to smell nitrogen oxide gases?

Answer 5

1-3ppm

Question 6

T/F: long exposure to a few ppm of nitrogen oxides can cause lower resistance to respiratory infections?

Answer 6

True

Question 7

What is the MOA of nitrogen oxide gases?

Answer 7

Direct mucous membrane irritation by nitric acid

Low water solubility —> pass to lower resp tract causing bronchi and alveolar damage —> pulmonary hemorrhage and edema

Death form anoxemia

Question 8

What are the clinical signs associated with nitrogen oxides?

Answer 8

Pulmonary edema, hemorrhage, emphysema, and inflammation of bronchioles

Cyanosis, methemoglobinemia, and necrosis of skeletal muscles

Question 9

What is the treatment of nitrogen oxide toxicity?

Answer 9

Supportive - fresh air, oxygen, diuretics, antioxidants

Methylene blue IV for methemoglobinemia

Question 10

What is the source of sulfur oxide gases?

Answer 10

Industrial pollutants

Fossil fuel combustion

Question 11

What occurs when sulfur oxides come in contact with mucus membranes?

Answer 11

Form sulfurous and sulfuric acids on contact with water -> sharply irritating

Question 12

T/F: sulfur oxide gases have no odor

Answer 12

False

Odor causes coughing, choking, and suffocation

Question 13

SO2 at about _____ppm is fatal to cats within 30-60mins

Answer 13

500

Question 14

T/F: SO2 at 500ppm for 1 hour is dangerous to grazing animals

Answer 14

True

Question 15

What is the MOA of sulfur oxides?

Answer 15

Direct irritation by sulfuric acids on mucous membrane and reflex bronchoconstriction
Lung damage
Death du to anoxemia

Question 16

What is the diagnosis and treatment for sulfur oxide toxicity

Answer 16

Diagnosis primarily on history

Ventilation, provide O2

Question 17

T/F: more than 80% of fire related deaths is from smoke inhalation and not from the burns

Answer 17

True

Question 18

T/F: older dogs are most likely to present for smoke inhalation and perish

Answer 18

False

Younger dogs are more likely to present for inhalation
Older dogs are more likely to perish

Question 19

What is the LD50 for smoke in dogs?

Answer 19

There is no LD50 for smoke because it is a heterogenous mixture

Question 20

What are the 3 MOAs of smoke?

Answer 20

Simple asphyxiants - inert gases that displace O2
Chemical asphyxiants- prevent uptake of O2
Irritates - chemically reactive on contact with mucus membrane

Question 21

Methane and CO2 have what MOA in smoke inhalation?

Answer 21

Simple asphyxiants replacing O2

Question 22

Hydrogen cyanide, H2S, and N2O has what MOA during smoke inhalation?

Answer 22

Irritants

Question 23

CO has what MOA during smoke inhalation ?

Answer 23

Chemical asphyxiants preventing uptake of O2

Question 24

Where can you see clinical signs due to smoke inhalation?

Answer 24

Respiratory -cough, dyspnea, tachypnea
CV-tachycardia, hypotension, dysarrhythmia
Irritation
CNS signs -agitation, confusion, ataxia, and abnormal posture
Surface burns

Question 25

What is the treatment of smoke inhalation?

Answer 25

O2
B2 agonist for bronchoconstriction
Remove soot from skin surface
Maintain airway patency

Question 26

What should you avoid using when treating smoke inhaltion?

Answer 26

Cough suppressants (eg opioids) 
Steroids

Question 27

Highly water soluble gases like sulfur dioxide, ammonia, and hydrogen chloride cause most injury where?

Answer 27

Upper airway
Irritant to mucous membranes —> inflammation and free radical formation
Edema

Question 28

Poorly water soluble gases like nitrogen oxides cause injury where in the respiratory system?

Answer 28

Lower respiratory tract
Pulmonary parenchyma/alveoli

Have slower reaction and delayed effect —> bronchospasm and inflammation

Question 29

T/F: inhaled soot increases the damaging effects of other gases in smoke

Answer 29

True

-soot binds the mucosa and allows other materials to adhere and react (eg sulfur dioxides)