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Inhalational injuries H.R.Sarreshtahdar , MD Occupational Medicine Specialist

Inhalational injuries H.R.Sarreshtahdar , MD Occupational Medicine Specialist. Irritant lung reactions. Many gases, fumes, and aerosols are directly toxic to the respiratory tract Site of effect is determined by: Water solubility High solubility (ammonia): irritation of upper respiratory

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Inhalational injuries H.R.Sarreshtahdar , MD Occupational Medicine Specialist

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  1. Inhalational injuries H.R.Sarreshtahdar, MD Occupational Medicine Specialist

  2. Irritant lung reactions • Many gases, fumes, and aerosols are directly toxic to the respiratory tract • Site of effect is determined by: • Water solubility • High solubility (ammonia): irritation of upper respiratory • Low solubility (O3): irritation of lower respiratory • Particle size • Large particles (>10μm): upper respiratory • Medium particles (3-10 μm): airways • Small particles (<3 μm): lung parenchyma

  3. Irritant lung reactions • Examples of some irritants: • Ammonia • HCl • SO2 • NOx • Phosgene • O3 • Clinical findings: • Immediate irritation of upper respiratory tract to late pneumonitis and pulmonary edema

  4. Management • Immediately obtain ABG + O2 therapy • Take a history (esp. attention to chemical asphyxiants) • Examine eyes, nose, pharynx for evidence of burns • Auscultate lungs • Baseline spirometry if subject is capable • Baseline CXray • Admit to hospital • Observe for 24-48h

  5. Simple Asphyxiants • Gases: • Methane, ethane, propane • Ethylene, propylene, acethylene • CO2 • N2 • NO • Effect: reduction of fractional inspiratory concentration of O2→ hypoxia • No toxic effects

  6. Simple Asphyxiants • Exposure: • typically in confined spaces (storage tanks, mines) • For gases heavier than air any low-lying semi-closed space with little air movement is dangerous Methane (mining) CO2 (food preservation, manufacture of dry ice,…) N2 (underwater work, mining, metallurgic operations, pressurizing oil wells)

  7. Simple Asphyxiants • Clinical findings: • Related on: • Asphyxiant concentration • Level of physical activity • Underlying medical status • Normal air O2: 21% • O2 (10-16%): tachycardia, tachypnea, exercise intolerance • O2 (6-10%): nausea, prostration, coma • O2 (<6%): rapid loss of consciousness

  8. Simple Asphyxiants Treatment • Immediate removal from exposure • Supportive measures (esp. supplemental O2)

  9. Toxic Asphyxiants Inhalation of asphyxiants which have toxicity to tissues • Carbon monoxide (CO) • Hydrogen cyanide (HCN) • Hydrogen sulfide (H2S)

  10. CO • An odorless, colorless gas • CO intoxication: the leading cause of death from gas inhalation • Exposure: • Incomplete combustion of fuels (vehicles, forklifts, generators, … esp. when used indoors) • Jobs: • Firefighters, petroleum refinery workers, furnace operators, …

  11. CO • Mechanism of action: • Binding to Hgb (COHb): • ↓ O2 binding capacity • Leftward shift of O2 dissociation curve • Binding to cytochrome oxidase: • Compromising cellular respiration • Clinical findings: • Headache, nausea, vomiting, malaise, loss of consciousness, coma, death, cardiac ischemia • Lab data: • ↑ COHb in cooximetry • Routine ABG is not helpful • EKG (MI without typical chest pain)

  12. CO Treatment • Immediate removal from exposure • 100% O2 • Hyperbaric oxygen

  13. HCN A colorless gas with bitter almond odor • Uses: • metal plating, and extraction of silver and gold salts from ores • Exposure: • thermolysis byproduct of many polymers • Jobs: • Pesticide workers, printing, soldering, firefighting, photography, paper production,… • Mechanism of action: • Binding to cytochrome oxidase • Clinical findings: • Dyspnea, dizziness, headache, confusion, loss of consciousness, coma, death

  14. HCN • Lab findings: • Blood cyanide level (not available) • Urine thiocyanate (not reliable) • Treatment: • Removal of exposure • Induction of metHgb (300 mg Na nitrite) • Detoxification of cyanide (sodium thiosulfate) • Supportive measures

  15. H2S A colorless gas with rotten egg odor • Exposure: • Many jobs (petroleum production and refinery, farming, chemical laboratory, excavators, fish processing, sewage workers,… • Mechanism of action: • Binding to cytochrome oxidase • Irritant effect on mucous membranes

  16. H2S • Clinical findings: • Irritant findings: airway irritation, burning eyes • Headache, dizziness, nausea and vomiting • Dermatitis, pneumonitis, pulmonary edema • loss of consciousness, coma, death • Lab data: • Blood sulfide level • Treatment: • Removal of exposure • Induction of metHgb (300 mg Na nitrite) • Supportive measures

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