Toxic Gases 2 Flashcards
What is usually the source of nitrogen oxide gas toxicity?
Incomplete reduction of nitrates during the fermentation process in silos (AKA silos fillers disease)
Also a major pollutant in fossil fuel burning
What colour are NO2 and N2O4 gases?
NO4 - reddish brown
N2O4- colourless
When mixed —> yellow brown
What happens when nitrogen oxide gases come in contact with mucous membranes?
Gases form nitric acid (HNO3) and nitric oxide (NO)
What odor does nitrogen oxide gases have?
Irritating chlorine like odor
At what level are humans able to smell nitrogen oxide gases?
1-3ppm
T/F: long exposure to a few ppm of nitrogen oxides can cause lower resistance to respiratory infections?
True
What is the MOA of nitrogen oxide gases?
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
What are the clinical signs associated with nitrogen oxides?
Pulmonary edema, hemorrhage, emphysema, and inflammation of bronchioles
Cyanosis, methemoglobinemia, and necrosis of skeletal muscles
What is the treatment of nitrogen oxide toxicity?
Supportive - fresh air, oxygen, diuretics, antioxidants
Methylene blue IV for methemoglobinemia
What is the source of sulfur oxide gases?
Industrial pollutants
Fossil fuel combustion
What occurs when sulfur oxides come in contact with mucus membranes?
Form sulfurous and sulfuric acids on contact with water -> sharply irritating
T/F: sulfur oxide gases have no odor
False
Odor causes coughing, choking, and suffocation
SO2 at about _____ppm is fatal to cats within 30-60mins
500
T/F: SO2 at 500ppm for 1 hour is dangerous to grazing animals
True
What is the MOA of sulfur oxides?
Direct irritation by sulfuric acids on mucous membrane and reflex bronchoconstriction
Lung damage
Death du to anoxemia
What is the diagnosis and treatment for sulfur oxide toxicity
Diagnosis primarily on history
Ventilation, provide O2
T/F: more than 80% of fire related deaths is from smoke inhalation and not from the burns
True
T/F: older dogs are most likely to present for smoke inhalation and perish
False
Younger dogs are more likely to present for inhalation
Older dogs are more likely to perish
What is the LD50 for smoke in dogs?
There is no LD50 for smoke because it is a heterogenous mixture
What are the 3 MOAs of smoke?
Simple asphyxiants - inert gases that displace O2
Chemical asphyxiants- prevent uptake of O2
Irritates - chemically reactive on contact with mucus membrane
Methane and CO2 have what MOA in smoke inhalation?
Simple asphyxiants replacing O2
Hydrogen cyanide, H2S, and N2O has what MOA during smoke inhalation?
Irritants
CO has what MOA during smoke inhalation ?
Chemical asphyxiants preventing uptake of O2
Where can you see clinical signs due to smoke inhalation?
Respiratory -cough, dyspnea, tachypnea
CV-tachycardia, hypotension, dysarrhythmia
Irritation
CNS signs -agitation, confusion, ataxia, and abnormal posture
Surface burns
What is the treatment of smoke inhalation?
O2
B2 agonist for bronchoconstriction
Remove soot from skin surface
Maintain airway patency
What should you avoid using when treating smoke inhaltion?
Cough suppressants (eg opioids) Steroids
Highly water soluble gases like sulfur dioxide, ammonia, and hydrogen chloride cause most injury where?
Upper airway
Irritant to mucous membranes —> inflammation and free radical formation
Edema
Poorly water soluble gases like nitrogen oxides cause injury where in the respiratory system?
Lower respiratory tract
Pulmonary parenchyma/alveoli
Have slower reaction and delayed effect —> bronchospasm and inflammation
T/F: inhaled soot increases the damaging effects of other gases in smoke
True
-soot binds the mucosa and allows other materials to adhere and react (eg sulfur dioxides)
