Asphyxiants produce respiratory embarrassment CO reduces oxygen carrying capacity of blood CO2 produces oxygen lack in tissues Hydrogen sulphide paralyses resp. center

Asphxiants (Irrespirable Gases) They include: Carbon dioxide Carbon monoxide Hydrogen sulphide Some war gases

Carbon Monoxide Colourless, odorless, non-irritant gas, light Formed by incomplete combustion of carbon and organic matter Sources : oil heaters, oil lamps, gas heaters, explosion in mines, exhaust of car engines, burning houses Affinity of CO for Hb is times greater than that of oxygen

Signs and Symptoms Saturation of HbSymptoms with CO 0-10%no symptoms 10-20%shortness of breath, headache, flushed skin 20-30%throbbing headache, buzzing in ears

muscular weakness, breathlessness, incoordination, 30-40% headache, dizziness, vomiting, mental confusion,

40-50%symp. Intensified, mistaken for drunkenness 50-70%coma, C.S resp. Int asp convulsions, resp. paralysis, death Above 70%resp arrest, fatal

Dose : At rest 0.1 % CO will result in stupor & coma in three hours. 1% CO stupor & coma will result in minutes. Treatment: PM app : cherry red, 5 gm COHb/100ml 1-2 cm liquid paraffin added over bld.sample.

Carbon dioxide Heavy, colourless, odorless, Formed : complete combustion of carbon containing comp, fermentation & decomposition of organic matter. Sources : manholes, refrigerating plant, wells, rebreathing in closed spaces.

Symptoms Pure CO2: instant death 20-30%: no effect for a while, fall of BP, diminished resp, headache, drowsiness, coma, death 40%: dyspnoea, drowsiness, muscle weakness. 50%:death from decreased oxygen.

Treatment : Tham, an amine buffer IV..

Hydrogen Sulphide Colorless, smell like rotten egg Found where sulphur containing organic matter is undergoing decay eg. sewers, cesspools, privies, tannery vats, artificial silk industry, human instestine during life. Body after death putrefaction

Signs & Symptoms Pure H2S : death 0.2% conc : death in few minutes Less conc : nausea, pain abdomen, laboured breathing, irregular heart action, convulsions,coma and death.

Treatment: PM appearance : offensive smell, bluish green colour of skin

OxyHb life MetHb dead SulphmetHb

War Gases  Lacrimators or tear gas : Chloracetophenon (C.A.P) Bromobenzyl cyanide (B.B.C) Ethyl iodoacetate (K.S.K)  Lung irritants/asphyxiants/choking : Chlorine (CI 2 )Chloropicrin Phosgene (COCI 2 )

 Vesicant or Blister gases : Mustard gas Lewisite  Sternutators/ Nasal irr./ vomiting gas Diphenyl chlorarsine (D.A) Diphenylamine chlorarsine (D.M) Diphenyl cyanarsine (D.C)

 Nerve/Blood poisons/Paralysants : Carbon monoxide Hydrocynic acid Hydrogen sulphide  Nerve gases : Toxic chemicals with action like acetylcholine  Miscellaneous : Yellow/Red rain MIC (methyl Isocyanate)

Lacrimators Fired in artillery shells Symptoms : Irritants of eyes, severe lacrimation, spasm of eyelid, temporary blindness. Treatment : Gas masks, normal saline(eyes), sodium bicarbonate solutions(nose.face)

Lung Irritants Chlorine & Phosgene are gases Chloropicrin & Diphosgene are liquid and fired in artillery shells Phosgene & Diphosgene are called green cross

Vesicants Fired in artillery shells Symptoms : Intense itching, blisters, ulcers, vomiting, hemolysis of RBC’s Treatment : Gas mask, special clothes, change clothes, wash with soap & water, attention to eyes, resp & burns is an antidote for lewisite.

Sternutators Fired in artillery shells Inhaled from air, swallowed in food & water Symptoms : sneezing, salivation, vomiting, nausea, headache Treatment : gas mask, symptomatic, sodium bicarbonate as mouth wash.

Miscellaneous Yellow/Red rain Methyl Isocyanate (MIC)

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