Asphyxiants.pptx

Asphyxiants (Gases) forensic investigation

1. Asphyxiants (Irrespirable Gases) Toxicology & Forensic Serology 1 Dr. Aamir Ali Khan Biochemistry

2. Asphyxiants An Asphyxiants gas , also known as a simple Asphyxiants, is a nontoxic or minimally toxic gas which reduces or displaces the normal oxygen concentration in breathing air. Breathing of oxygen-depleted air can lead to death by asphyxiation (suffocation). Because Asphyxiants gases are relatively inert and odorless, their presence in high concentration may not be noticed, except in the case of carbon dioxide (hypercapnia).

3. Asphyxiants 1 Asphyxiants mainly produce respiratory embarrassment; important asphyxiants include Carbon Monoxide (CO) Reduce oxygen carrying capacity Carbon dioxide (CO2) Lack of oxygen in tissue Hydrogen Sulphide (H2S) Paralyses respiratory center

4. Carbon Monoxide (CO) Toxicology & Forensic Serology 4 Colorless, odorless, non irritant gas Cant perceived by senses Incomplete combustion of carbon & organic matter = Carbon monoxide Sources; illuminating gas , oil heater, gas heater, vehicle engine etc

5. Car b o n Mon o xide (CO) cont.. 5 CO has 200-300 time higher affinity to Oxygen Displace oxygen form carboxy hemoglobin and is more stable Ultimately result in anoxia (severe depletion of oxygen).

6. Sign & Symptoms Toxicology & Forensic Serology 5 Carbon Monoxide Poisoning: Here’s What You Need To Know | Just Boilers

7. Sign & Symptoms COHb % Saturation Symptoms No appreciable Symptoms Breath shortness, mild headache, flushed skin Throbbing headache, buzzing in ear, dulling of senses, muscle weakness Severe headache, nausea, vomiting, breathlessness, incoordination, muscle weakness, dim vision, impaired judgment Symptoms intensified, may be mistaken with drunk, mental confusion, memory loss, palpitation and dyspnea ( Shortness of breath) Intermittent asphyxia convulsion, coma, Cheyne-Stokes respiration ( a rare abnormal breathing pattern) , respiratory paralysis & death 0-10 10 - 20 20 - 30 30-40 40 - 50 50 - 70 >70 Rapidly fatal due to respiratory arrest 6

8. Diagnosis of CO https ://w ww .verywellhealth.com/carbon-monoxide-poisoning-diagnosis Toxicology & Forensic Serology 8

9. Blood Test Collection of Blood Sample for Chemical Analysis Collect the blood from peripheral veins. Add sodium fluoride as a preservative and preferably seal the bottle with a layer of liquid paraffin on the top. Method 1 : a suspected sample diluted with four times its volume of water & add few drops of 3 % aqueous tannic acid to solution and shaken well If >10 % CO present, it form pinkish white precipitate 9

10. Blood Test Method 2: A suspected blood sample diluted with 20 times its volume of water & 10 drops of 10 % caustic soda added to it. Normal blood becomes greenish brown but Blood containing >10 % CO retains its bright red color as no methemoglobin is formed Toxicology & Forensic Serology 10

11. Carbon Dioxide Poisoning 1 Toxicology & Forensic Serology This is heavy, colorless, odorless & Poison gas Result from complete combustion of carbon containing compounds Formed due to fermentation & decomposition of organic matter Sources; refrigerating plants, manholes, wells, re- breathing close spaces

12. CO2 P oisonin g co n t … 1 1 Toxicology & Forensic Serology Pure CO2 inhalation may cause vagal inhibitory response ( Stopping the heart by stimulation of the vagus nerve in the neck . This can be caused by pressure on the neck) , spasm of glottis , instant death > 50%CO2 may result immediate unconsciousness & death from deficiency of oxygen supply to brain & tissues Unexpected death from CO2 under anesthesia

13. Hydrogen Sulphide Poisoning 1 2 Toxicology & Forensic Serology Sulphurated gas; a colorless gas with rotten egg smell Found if Sulphur containing compound under decay Such as sewers , formed during artificial silk manufacturing etc Formed in human intestine during life and due to putrefaction after death Converts oxyhemoglobin to methemoglobin & sulphmethemoglobin after death

14. H2S P oisonin g Co n t.. 1 3 Toxicology & Forensic Serology If pure H2S inhaled death occur at once Result in paralysis of the respiratory Centre A 0.2 % concentration in air proved fatal in few minutes

15. Re f e r ence Toxicology & Forensic Serology 2 Text book of Medical Jurisprudence, Forensic medicine and Toxicology, BV Subrahmanym Seventh edition