Chapter 36: Asphyxiants

**Asphyxiants**

gaseous poisons, which produce respiratory embarrassment, leading to asphyxia.

**Chemical asphyxiants**

reduce the body’s ability to absorb, transport, or utilize inhaled oxygen.

**Simple asphyxiants**

These are inert gases and they deprive tissue of oxygen by their ability to displace oxygen.

**Respiratory / pulmonary asphyxiants**

are gases, which can damage the respiratory tract by destroying the integrity of mucosal barrier and produce non-cardiogenic pulmonary edema, which impairs the oxygen diffusion across the alveolar membrane.

**Systematic asphyxiants**

gases, which produce significant systemic toxicity by specialized mechanisms.

**Carbon monoxide**

________ is a colorless, tasteless, odorless and nonirritant gas, produced whenever there is incomplete combustion of carbon.

Carbon monoxide

_______ has got 200 to 300 times more affinity for hemoglobin (Hb) than oxygen (O2) forming carboxyhemoglobin, which are quite stable

Endogenous CO

______ resulting from hem degradation constitutes another source of CO. It is an end product of normal metabolism and is formed during the conversion of heme into biliverdin.

Pulse oximetry

This is a simple non-invasive technique of detecting oxygen saturation measured by discrete wavelengths of light corresponding to saturated and unsaturated hemoglobin (660 and 940 nm) by a photodetector.

Chest radiograph

This radiograph may reveal ground glass appearance, perihilar haze, parabronchial cuffing, and intra-alveolar edema.

Dry Ice

Solid form of CO2

War gases

Chemicals that are used only in warfare.

Lachrymators (Tear gases)

* Chloracetophenon (CAP), Bromobenzyl cyanide (BBC), Ethyl iodoacetate (KSK)
* These war gases are harmless to life.

Lung irritants

* Chlorine (Cl2 ), Phosgene (CO Cl2), Diphosgene
* These war gases can be fatal and kill the victim.

Nasal irritants (Sternutators)

* Diphenyl chlorasine (DA), Diphenylamine chlorasine (DM), Diphenyl cyanarsine (DC)
* Vapors can result in intense pain and irritation in the nose and sinuses leading to sneezing, malaise, headache, and salivation followed by nausea, vomiting and chest pain.

Nerve gases

* Chemical with acetylcholine-like action
* They are compounds related to phosphate esters in action and toxicity. They are colorless and odorless volatile liquids.

Paralysants

Carbon monoxide (CO), Hydrocyanic acid (HCN), Hydrogen sulfide (H2S).

Vesicants

* Mustard gas, Lewisite.
* It can also develop severe irritation of the skin especially over the oily areas, such as the face, axillae, pubis, scrotum, etc., especially over the moist areas.
* There can be inflammation of the stomach leading to nausea, vomiting, pain abdomen, diarrhea, etc.

Methyl isocyanate

It can be considered under several classifications, namely: agrochemicals, war gases, irritants and miscellaneous poisons.

hydrocyanic acid

Liquid form of Cyanide

Cyanides

These are protoplasmic cytotoxic poisons. They act by inhibiting cytochrome oxidases for utilizing O2 in a cell, leading to internal asphyxia (cellular asphyxia), leading to death. It can also act on other enzymes mildly. It also acts as a corrosive on the mucosa.

ammonia

At room temperature, _____ is a highly water-soluble, colorless, irritant gas with a unique pungent odor.