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Clinical Problem Solving in Poisoning 3

Clinical Problem Solving in Poisoning 3. Group F: Tse Ka Hei Tsui Tsz Kwan Wong Kin Wai Wong Sze Nga Yam Po Chu Patricia Yeung Yat Sing Kevin. Scenario. Retired executive Retrosternal chest pain 3-hr work in basement workshop

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Clinical Problem Solving in Poisoning 3

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  1. Clinical Problem Solving in Poisoning 3 Group F: Tse Ka Hei Tsui Tsz Kwan Wong Kin Wai Wong Sze Nga Yam Po Chu Patricia Yeung Yat Sing Kevin

  2. Scenario • Retired executive • Retrosternal chest pain • 3-hr work in basement workshop • Apply commercial paint & varnish remover to a wooden chest of drawers

  3. Scenario • On admission • On paint-remover label • 80% methylene chloride • Used only with adequate ventilation • Dx • Anterior wall myocardial infarction • Treat conservatively; D/C after 2 wks • Resume to work • Severe MI complicated by cardiogenic shock • Death after 2nd D/C

  4. Methylene chloride • Chemical name • Dichloromethane • Source • Solvents • Paint stripping products • Degreasers • Properties • Highly lipid-soluble • Volatile

  5. Methylene chloride • Toxicokinetics • Absorption: inhalation, dermal absorption • Metabolism: CYP450 (liver)  CO + CO2 • COHb level can be as high as 50% • Peak level may be delayed > 8 hrs

  6. What happened? CO poisoning

  7. What happened? • Carboxyhemoglobin • Affinity: CO >> O2 (250x) • Shift oxyHb dissociation curve to left •  oxygenation   CO  AMI

  8. What happened? • Carboxymyoglobin • Affinity: CO > O2 (60x) • Myocardial depression: dysrrhythmia, ischemia • Even in mild exposure • Pre-existing heart disease

  9. Any specific investigations? • Further questions in Hx before Ix • Prior Hx of cardiovascular disease  risk factors • Hx related to painting work • Duration • Frequency • Any other exposures to CH2Cl2 • Glues

  10. Any specific investigations? • COHb level • Normal level • Non-smoker: < 5% • Smoker: <12% • Only confirm CO poisoning • Not correlate w/ severity/ outcome • Redistribution of methylene chloride • Duration of exposure • Any previous prolonged treatment w/ oxygen

  11. Any specific investigations? • Formic acid in urine • Metabolite of CH2Cl2 • Direct measure CH2Cl2 • Air breathed out • Blood level

  12. Any specific investigations? • ABG • Confirm metabolic acidosis • Serious CO toxicity  worse Px • Oxygenation • Pulse oxymetry • Not reliable ∵ interference of COHb • Creatine kinase test • Rhabdomyolysis • Urine myoglobin • Rhabdomyolysis

  13. Any specific investigations? • LFT • Hepatotoxicity • RFT • Nephrotoxicity • Hypokalemia due to metabolic acidosis • Blood glucose • Esp. if altered mental status

  14. How to avoid tragedy? • Improve ventilation • Wear proper clothing • Avoid long term exposure • Avoid future exposure • Use alternative agent

  15. How to avoid tragedy? • 100% non-rebreather face mask • Promote cellular resp • Reduce elimination t1/2 of COHb • Continue until asymptomatic

  16. Reference • Ford: Clinical Toxicology, 1st ed., 2001 W.B. Saunders Company • Marx: Rosen’s Emergency Medicine: Concepts and Clinical Practice, 5th ed., 2002 Mosby • Agency for Toxic Substances and Disease Registry • http://www.atsdr.cdc.gov/tfacts14.html

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