Asphyxiants comparison as per KUHS UG syllabus

1. ASPHYXIANTS MECAHANISMOF ACTION CLINICAL FEATURES DIAGNOSIS MANAGEMENT AUTOPSY
APPEARANCE
FORENSIC
IMPORTANCE
1.HYDROGEN
CYANIDE.
Cyanidearewhite
powders
Prussicacid
(2%)
Scheelesacid
(4%)
20-40% persons
cannot smell the
gas, sex-linked
recessive trait.
HCN normal
constituent
(15 to
30microgram)
Inhibits cytochrome
oxidase, carbonic
anhydrase. It blocks final
step of oxidative
phosphorylation and
preventsformationof ATP.
Cyanide acts by reducing
oxygencapacityof blood.It
preventsuptake of oxygen
for cellular respiration
Cause histotoxic anoxia
Absorbed from respiratory
system. Alkaline cyanides
wheningestedare converted
by hydrochloric acid in the
gastric juice into chlorides
and hydrocyanic acid is
liberated. Symptoms due to
cellular hypoxia.
CNS,GIT,RS,CVS
manifestations.Tobacco
amblyopia,Lebershereditary
optic atrophy, tropical
ataxia
Lee Jones test
(Gastric aspirate
with ferrous
sulphate and 2%
NaOH and 10
drop HCl resultsin
greenblue colour.
Smell of bitter
almonds, similar
to crushed
tapioca leaves
Stabilisation, Amyl
nitrate(0.2ml
inhalation,
Sodiumnitrate
(0.3gm)insterile water,
form methHb
competes with
cytochrome oxidase,
through same needle
give
Sod: thiosulphate50%
solution it converts
cyanide to thiocyanate
which is excreted in
urine.
Hydroxocobalamin
infusionform nontoxic
cyanocobalamin
Corrosion of
mouth and
nostrils,
smell of
bitter
almonds.
Hemorrhagic
gastritis,
pulmonary
edema.
Bright red
postmortem
staining
Suicidal pills
Homicidal
Judicial execution
(cyanide gas)
2.CARBON
MONOXIDE
(Cellulartoxin)
Absorbedacrossthe
alveolus,combineswith
Hb.COaffinityto
myoglobinisabout40
timesgreaterthanO2
which cause myocardial
depression. Ithas200 to
300 time’sgreateraffinity
for Hb. It inhibitselectron
transportby blocking
CytochromeA3 oxidase and
P450.It interfereswith
other ferroprotein suchas
myglobin&enzymes
10%-breathlessness,
headache
20-30%-Throbbingheadache,
irritability
30-40%-Cherryred
discoloration,confusion
40-50%-Confusion,
hallucination
50-60%-Syncope,coma
70-80%-Coma, depressed
reflex,weak pulse.
80%- Deathfrom respiratory
arrest.Death due to anaemic
anoxia.
CO oximeter
BloodTests:
Kunkelstest or
tannicacid test:
cherryred colour
Hoppe Seylers
test:blood&
10%NaOH, CO
turn pink.
Spectroscopy:
bandin yellow
between D&E ,no
changeafter
addingNH3 S.
Removal,100%
hyperbaricO2 ,
inhalationof O2 ata
pressure greaterthan
one atmos, correct
metabolic
acidosis,cerebral
oedema
Cherryred
discolouration
of skin, blood,
cutaneous
bullae.
Necrosisof
putamen,
globuspallidus
CO automatism
Accidental poisoning

2. ASPHYXIANTS MECHANISM OF
ACTION
CLINICAL FEATURES DIAGNOSIS MANAGEMENT AUTOPSY
APPEARANCE
FORENSIC
IMPORTANCE
2.CARBON DIOXIDE Simple asphyxiant
preventingtissue
fromobtaining
oxygen
5%- labouredbreathing
10% ataxiaunconsciousness
40%-dyspnoea, discomfort
muscle weakness
50%- dyspnea,tightness
fullnessof headandringing
inears,lossof muscular
power,drowsiness,coma
and death.
60-80%- Unconsciousness,
convulsion,coma,and
death.
History,Cyanosis,
congestion
Remove fromsource
Artificial respiration
OXYGEN administration
Cardiac stimulants.
congestion,
cyanosis,
featuresof
respiratory
failure
GHOST WELL
Accidental poisoning
inpersonsentering
unusedwell.
3.HYDROGEN SULPHIDE
Formedbydecompositionof
organicmatter.
Industrieswhere sulphur
compoundisused.
Sewergas
Combineswith
methhaemoglobin
to form
sulphmethhaemogl
obin
It interefereswith
cellularrespiration
by inhibing
cytochrome oxidase
Tolerable limit
20ppm
Cough,giddiness,nausea,
feelingof oppression,
laboredbreathing,heart
beatirregular
History,Cyanosis,
congestion
Remove fromsource
Artificial respiration
OXYGEN administration
Amyl nitrate inhalation
and sodiumnitrite
infusion
Rottenegg
odour,signsof
asphyxia,
greenish
discoloration
of skin,viscera,
bronchial
secretions
Occupational hazard
insewerworkers