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Smoke And Burns

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  • 1. SMOKE INHALATION AND FIRE TOXICOLOGY Steven A. Godwin MD University of Florida /HSC
  • 2. Background • Account for 50% of fire deaths • Multiple factors contribute to M and M – Local pulmonary insult – Inhaled pulmonary and systemic toxins – Asphyxia
  • 3. Mechanisms of Local Pulmonary Injury • Thermal Injury • Chemical Injury • Multifactorial
  • 4. Thermal Injury • Rarely affects parenchyma • Damages primarily mucous membranes • Initial 24 hours is key
  • 5. Chemical Injury • Physical properties – anatomic location – extent of absorption • Length of exposure
  • 6. Physical Properties of Chemical Inhalants • Upper airway irritants – Larger, highly water soluble particles • Alveolar injury – Associated with less water solubility and smaller particles
  • 7. Multifactorial Injury • Respiratory epithelium necrosis • Cilia inactivation • Type II pneumocytes and alveolar macrophage destruction • Capillary leak syndrome
  • 8. Systemic Fire Toxins • Chemical asphyxiants Carbon monoxide Cyanide • Simple asphyxiants Nitrogen Argon Hydrogen Methane Helium Ethane Carbon dioxide
  • 9. Chemical Asphyxiants • Carbon monoxide – Colorless, tasteless, odorless gas – Leading cause of reported toxicologic deaths – Byproduct of incomplete combustion – Pyrolysis of any carbon containing material
  • 10. Mechanism of CO Toxicity • CO competes with oxygen binding to hemoglobin, myoglobin, and cytochrome oxidase • Results in global hypoxia, muscle ischemia, and cellular hypoxia
  • 11. CO Toxicity • Impaired O2 off-loading • Leftward shift of oxygen dissociation curve • Fetal tissue at increased risk • Neurologic and cardiovascular systems primarily affected
  • 12. Physical Findings and Carboxyhemoglobin levels • O % No symptoms • 10 % Frontal HA • 20 % HA, DOE • 30 % N/V, dizziness, blurred vision, poor judgement • 40 % Confusion, syncope • 50 % Coma, seizures • 60-70 % Hypotension, death
  • 13. Pediatric Exposures • Up to 17 % of acute exposures die • Up to 48 % of acute exposures may require CPR • Newborns at highest risk • Confused for colic • Implicated in some cases of SIDS
  • 14. Cyanide Toxicity • Suspect in fires involving synthetics – wool, silk, nylon, paper, upholstery, plastics, polyurethane, asphalt • Victims have bitter almond breath odor
  • 15. Mechanisms of CN Toxicity • Inhibits ATP production by binding with the ferric moiety of cytochrome oxidase • Blockade in the mitochondrial O2 • Severe hypoxia despite presence of O2
  • 16. Presentation of CN Toxicity • Mimick signs of hypoxia without cyanosis • Physical signs are non-specific: may include hyperventilation, anxiety, decreased LOC, seizure, coma, cardiac arrhythmias
  • 17. Clinical Clues • History most important clue • Suspect in any patient found to be comatose, bradycardic, and severely acidotic w/o findings of cyanosis or hypoxia • Diagnosis supported by bright- red retinal vessels, oral burns and odor
  • 18. Initial Evaluation in Smoke Inhalation • History, History, History, History • A,B,Cs • PE: HEENT: retinal veins, mucous membranes, facial burns, singed nasal hairs or presence of carbonaceous sputum, dysphonia
  • 19. Initial Evaluation in Smoke Inhalation • PE continued: Neck: stridor Cardiovascular: ectopy Pulmonary: wheezing and rales Skin: cherry red discoloration, burns, chemical exposures, bullae
  • 20. Airway Evaluation • Fiberoptic evaluation recommended in significant exposures due to unreliable physical signs • Close observation with low threshold for intubation
  • 21. Laboratory • Essential test: ABG with co-oximetry COHb level Urine pregnancy test Chest x-ray • Additional test to consider Electrolytes CPK levels CBC Urine myoglobin Coagulation studies
  • 22. ABG and Pulse Oximetry • Beware the saturation gap – Ask for measured oxygen saturation – May calculate poor man’s (UMC) COHb level • Evaluate severe acidosis
  • 23. Initial Management • 100 % Oxygen • Airway evaluation with brochoscopy if indicated • Supportive care with treatment of burns • No role for steroids or antibiotics • Observation period depends on exposure
  • 24. Initial Management • Healthy asymptomatic patients with normal blood gases may be discharged • Exposure to agents with low solubility (phosgene) need longer observation • Exposure to local irritants (hydrogen chloride, sulfur dioxide) treat symptomatically and observe
  • 25. CO Management • Rules of thumb for the elimination half- life of CO Room air 240-320 minutes 100 % oxygen at 1 atm 60-90minutes HBOT with 3 atm 23 minutes
  • 26. Hyperbaric Therapy • Dalton’s Law: Pt=PO2 + PN2 + Px – States the ratio of gases doesn’t change despite the change in total pressure – The individual partial pressures do change • Increases Oxygen content to 6.8 %
  • 27. CO Management • Guidelines for Hyperbaric therapy – COHb > 25% – COHb > 15% in patient with coronary dz – COHb > 15% or with symptoms in pregnancy – COHb > 15% in a young child EKG changes pO2 < 60 mmHg Metabolic acidosis Abnormal thermoregulation
  • 28. CO Management • Goals of oxygen therapy in mild exposures: – Treat until COHb level < 5 % and asymptomatic – Admit patients with cardiac dz for observation
  • 29. CN Management • Lilly Cyanide Kit – Amyl nitrite – Sodium nitrite – Sodium thiosulfate
  • 30. Mechanism of Action of Antidote Kit • Amyl nitrite and sodium nitrite converts Hb > methemoglobin > binds CN > cyanomethemoglobin > rhodenase metabolizes CN to thiocyanate (enhanced by sodium thiosulfate) > renal excretion of sodium thiocyanate
  • 31. Hydroxycobalamin • Non- toxic • Binds CN and is excreted by kidneys as cyanocobalamin • Used in Europe • Awaiting FDA approval
  • 32. Outpatient Burn Care • 1st Degree – Superficial Burns • 2nd Degree – Superficial Partial Thickness – Deep Partial Thickness • 3rd Degree – Full Thickness
  • 33. Superficial Burns • Superficial epidermis only • Painful, erythematous and w/o blisters • Usually due to sunlight or short flash • No Scar
  • 34. 2nd Degree Burns • Superficial Partial Thickness – Full epidermis and may involve dermis – Red, blistered, weeping, and painfull – Often scalds and short flashes – No scarring
  • 35. 2nd Degree Burns • Deep Partial Thickness – Usually spares deep dermal structures – Severe blistering or waxy appearance – Often confused with full thickness – Scar on healing
  • 36. 3rd Degree Burns • Destruction of dermal layer • Flames, scalds, and chemical and electrical contact • White, charred inelastic skin • Thrombosed vessels • Scar with contractures
  • 37. Second Degree Depth of Burn
  • 38. Third Degree Depth of Burn
  • 39. Minor Burn Management • The 5 Cs: – Cut – Cool – Clean – Chemoprophylaxis - bacitracin, Silver Sulfadiazine – Cover
  • 40. Don’t Forget Pain Control!!
  • 41. Major Burn Evaluation • Adult Body Surface Area: “Rule of Nines”
  • 42. Major Burn Evaluation • Pediatric Body Surface Area: “Rule of Nines”
  • 43. Severe Burn Management • Airway – Assess for injury and establish control early • Breathing • Circulation – Fluid Resuscitation – Monitor Urine Output
  • 44. Fluid Resuscitation • Rule of thumb: – 1 ml of urine / kg / hr for children under 30kg – 30-50 ml /kg / hr output for adults
  • 45. Parkland Formula: Only a Guideline • Estimate of fluid requirements in partial and full thickness burns • 2-4 ml / kg / % BSA burn over first 24 hours • 50% of Ringer’s Lactate give over 1st 8 hours with rest administered over next 16 hours
  • 46. Criteria for Transfer • Partial / Full thickness burns greater than 10% BSA in patients > 55 yo and < 10 yo. • All other age groups with burns > 20 % BSA • Partial / Full thickness burns to face, hands, eyes, ears, feet, genitalia, or perineum or those overlying major joints • 5% Full thickness in any age group • Significant electrical burns • Significant chemical burns
  • 47. Criteria for Transfer • Inhalation injury • Burn injury in patients with complicating co- morbid illnesses • Children in facilities lacking appropriate resources to aid in rehab • Patients requiring special long term support including children in abuse cases
  • 48. Questions
  • 49. THE END