04 toxic gases
TRANSCRIPT
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By
Dr.Nirmala Perera
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Irritant Gases- causes irritation of therespiratory tract
Simple Asphyxiants- interferes withgaseous exchange only. They are notabsorbed
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Clinical Asphyxiants- Are absorbed into thelungs and causes various actions
Eg combines with Hb
Causes haemolysis
Interfere with cellular oxidation
Depress the brain and causes respiratory depressionand paralysis
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Simple asphyxiant gas
Sources- In anaesthesia,
Industrial- eg. Mines, disused wells, pits, shipholds, burning of lime, wood & coal, BreweriesMineral water plants
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Normal levels- O.3% > 3% - Headache, drowsiness, dizziness,
giddiness, muscle weakness ( prevents runningaway from the area)
10% - loss of consciousness
25-30% - minimal fatal concentration
60- 80% Instance collapse and death (tissueanoxia)
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It is odourless, rapidly absorbed when inhaled andcombines with haemoglobin to form carboxy-haemoglobin which is stable than oxy-
haemoglobin.
The affinity of CO for Hb is more than Oxygen
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Coal gas
Exhaust fumes of motor vehicles and other engines
Incomplete combustion in closed surroundings
Industrial gases
Circumstances : Suicidal and accidental
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The symptoms depends on the bloodconcentration of CO
Up to 20% - no symptoms
3%- street cleaners, traffic policemen
5%- heavy smokers
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20% - Headache, dizziness and malaise
30% - giddiness & mild shortness of breath
40% - Confusion, in-coordination, staggering,fatigue of muscles
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50%- drunken gait, slurred speech,incoordination, exhaustion, vomiting, flushing,
sweating & pink colour of skin (mimicsdrunkenness and drug intoxication)
60% - respiratory distress, dilated pupils, loss of
consciousness 70% - coma & death
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History of exposure
Pink colour
Clinical features
Blood analysis( 5-10ml of blood with anti-coagulant)
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Pink colour of the skin, hypostasis, blood andinternal organs
Symmetrical softening of the basal ganglia
Hypostatic pneumonia (delayed death)
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SOURCES
Cyanide Gas
Fumigation of ships
Spraying in fruit orchards
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Cyanide saltsUsed in electroplanting, goldplating, photography & engraving
Laboratory useCyanide capsules
Cyanogenic Glycosides in plantmaterial
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SUICIDE- Biting of cyanide capsule by terrorists Ingestion of liquid potash by those in thejewellery/electroplating trade
Ingestion by laboratory workers
ACCIDENTAL Faulty fumigating techniques Laboratory accidents Plant material
HOMICIDAL Introduced into food or drink War gas used in world war 1 Gas chambers in Germans in world war II Execution by cyanide gassing/ingestion (USA)
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http://rds.yahoo.com/_ylt=A9G_RtrfUmZGGB8AXROJzbkF;_ylu=X3oDMTBwczV0OXVlBHBvcwMxBHNlYwNzcgR2dGlkA0kwNjZfODg-/SIG=1g1241bhm/EXP=1181197407/**http%3A//images.search.yahoo.com/search/images/view%3Fback=http%253A%252F%252Fimg.search.yahoo.com%252Fsearch%252Fimages%253Fei%253Dutf-8%2526fr%253Dslv8-%2526p%253DPhoto%252520of%252520cyanide%252520poisoning%26w=160%26h=160%26imgurl=safety.chemistry.unimelb.edu.au%252Fimg%252Fcyanide.png%26rurl=http%253A%252F%252Fsafety.chemistry.unimelb.edu.au%252Fcyanide.php%26size=86.1kB%26name=cyanide.png%26p=Photo%2Bof%2Bcyanide%2Bpoisoning%26type=png%26no=1%26tt=124%26oid=dc014f4c3fdb02bc%26ei=UTF-8 -
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TWO FOLD ACTION
Inhibits the enzyme Cytochrome Oxidase
Acts as a corrosive because of its alkaline radical
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The rapidly absorbed cyanide is carried to thetissues in the blood stream
A cellular poison Strong affinity between cyanide and cytochrome
oxidase
Interfere with cellular utilization of oxygen
The cell cannot use oxygen although there isabundance of it in the blood stream
Cause cellular anoxia- Histotoxic or cytotoxic
anoxia
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SMALL DOSES Vertigo, headache, difficulty in breathing, loss of
muscle power & giddiness
LARGE DOSES Rapid loss of consciousness, collapse, twitching,
convulsions & death
The same is true for higher concentration of cyanidevapour
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History
Clinical features
Pink colour of extremities Smell of bitter almonds in the breath
The ability to smell is an inherited character.
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Red colour of skin, hypostasis, blood andvascular organs
Odour of bitter almonds or may be ammonia
Diffusely red mucosa of the GIT with orwithout areas of corrosion
Remnants of the capsule with cut injuries inthe mouth
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Embalming with formalin will rapidly
destroy cyanide
Postmortem decomposition produce tracesof cyanide
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Carbon dioxide- Accidental poisoning Co Suicidal and accidental poisoning
possible
CN- Suicidal and accidental poisoningpossible
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