Toxic Inhalation Dr. Anas Khan

1. Toxic InhalationDr. Anas Khan

2. Paracelcus: • Everything is a poison. • Only the dose differentiates a poison from a remedy.

3. Basics: • Be familiar with your area. • Mostly it’s 1 material.

4. Basics: • MSDS www.msdssearch.com • Concurrent Trauma • NFPA:

5. Basics: • Physical Properties: state, particle size, conc, solubility, boiling-melting points, color, odor, flash point, thermal & pressure reactions. • Chemical Reactions:.. • Classification Systems

6. Basics.. • Biologic Interaction: duration, exposure limits, RR & depth, host defense, warning Sx. • Basic Toxicology: dose-response relationship (not for Cancer). • Toxico-kinetics: what the body does to poison (absorption, distribution, metabolism, excretion). • Toxico-dynamics: cellular & molecular MOA of a poison.

7. Toxidromes: • Irritants: ammonia, chlorine, phosgen. • Asphyxiant: Simple (CO2, Nitrogen), Systemic (CO, cyanide, sulfides, azides). • Cholinergic: excess Ach. • HCO: (propane, toluene – chloroform)

8. Poison Rx Paradigm: ABCDE A: Alter Absorption, (remove, decon, dilute, 2ry cont) Antidote (few) B: Basics C: Change Catabolism D: Distribute Differently E: Enhance Elimination

9. Basic Summary: • Identification (Dx). • The rest is easy; you can look it up, call an expert. • The emergency response as planned.

10. Case Scenarios

11. Case 1 RC called and bringing 6 pts from a factory.. Local disaster, No communication.. Sx: lacrimation, rhinorrhea, burning sensation in the throat, laryngeospasm, stridor..

12. Irritants • Local corrosive effect, water solubility: High: Ammonia, Formeldehyde, HCl, SO2 (nostril till voc cords, mainly mm.) Moderate: Cl2 (upper RT > lower). Slight: NO2, phosgen (unaware, delayed).

13. Action Decon A: Suction, +/- ETT. B: O2, Nebs, +ve PEEP. C: IVF, monitor overload. D: AMS or Sz (hypoxia). E: Undress, vent with 100% Ox.

14. Case 2 • January night, a 22 yo male brought by his friend from Estraha, unconsc, forehead contusion. • The friend said he became dizzy before brief Seizure & typical post-ictal confusion. • Mildly pale, TC.. • Now the companion is having headache..

15. Asphyxiants Simple: CO2, Smoke, Methane, Propane, Helium, Nitrogen, ANY gas.. Systemic: Carbon-monoxide Met-Hb forming compounds: nitrites Cyanogenics Sulfides, Azides

16. Systemic Aspyxiants: CO - Carboxy-Hb  decrease transport & release. - Binding to myoglobin: • impairs tissue O2 delivery • CO binds to cytochrome oxidase • in mitochondria inhibiting • O2utilization and aerobic metabolism - Lipid peroxidation in CNS

17. Systemic Aspyxiants: MetHb • Not meth-. • Nitrite/Nitrate, aniline. • Oxidize Fe+2 (ferrous) to +3 (ferric) in Hb (Met-Hb)  Incapable of transporting O2  Hypoxia, decrease ATP • Direct VD.. • Brownish blood, cyanosis (10% MetHB). • T ½: 1-3 hr

18. Systemic Aspyxiants: Cyanogenics: • Body eliminates non-toxic levels of cyanide. • Cyanide has a high affinity for Fe+3, binding with it in the cytochrome oxidase. • Free cyanides binds to cytochrome oxidase  aerobic metabolism. • 2ry contamination. • Air hunger, AGMA, LA > 10 • “arterialization” of venous blood .

19. Systemic Aspyxiants: Azides & Sulfides • Similar to Cyanides • + local Irritation • 2ry contamination • Azides: VD • Sulfides: rotten eggs (gas eye, knock down)

20. Poison Paradigm Treatment: • Alter Abs & Elimination: 100% Oxygen & adequate vent • CO: 300 min – 90 min – 30 min • HBO: cardiac, cerebral , LA, >25%, pregnancy (15%) • Irritant gases & Azides: no Ad

21. Methylene blue: • Cardiac, cerebral or MetHb> 30% • “Not cyanosis” • CI: G6PD, MetHb red def. • 1-2 mg/kg over 5 min, repeat 30-60 min. • SE: n, v, HA, blue-green urine, hemolysis.

22. Nitrite: • For cyanogenic & sulfide. • Induces MetHb (binds to cyanide instead of cytochrome oxidase), Nitric Oxide. • CI: Allergy, MetHb > 40% or iatrogenic, CO, hypotension, allergy, severe RF. • Amyl-:1 amp inh 30 sec/min for 3 min. Low efficacy + ?abuse. D/C if Na-nitrite. • Na-: 1 amp IV over 5 min.

23. Sodium Thiosulfate: • For cyanogenic only. • SE: n, v, site inj. • 1 amp IV over 15 min • HepaticRhodanese: catalyses Cyanide + Thiosulfate Thiocyanate (less toxic & excreted in urine) The main rate limiting factor detoxifying cyanide

24. Hydroxycobalamine: • For cyanide, CO, confined fire. • SE: everything turns red. • 5 g IV over 15 min. • MOA: distribute CN differently.

25. Case 3: 2 janitors were brought by their sponsors, they were: Unconsc, Sz, miosis, mydriasis, fasciculation, sweating, lacrimation, urination, BC, TC

26. Case 3:

27. Organo-phosphates:

30. CNS (M & N): • Confusion • Convulsion • Coma

31. Aging: • Minutes  nerve agents (Soman) • 2 days  pesticides

32. Mx: DECON A: Secretion  Suction + Atropine B: C: BC, Hypotensive  Atropine D: Sz  Benzo  Atropine + 2- PAM

33. Atropine: • Competitive antagonist M only • Para-sympatholytic. • Cannot counter-react nicotinic Sx • No Ach-estrase regeneration. • 0.5 – 2 - 6 mg IV, (0.01-0.04 mg/kg) q5min, till Bs resolve.

34. Pralidoxime: (2 PAM, Protopam) • Dephophrylate (reactivate) phosphorylated Ach-estrase, that not yet irreversibly covalent bonded • Also it binds to free organo-phosphate • Indications: Nicotinic or CNS • Relative CI: MG, RF, No AW kit • SE: laryngeospasm • 1 – 2 mg IV over 5 – 10 min, infuse 500 mg/h for 24 h

37. Pyrethrins: • Neurotoxic • Na channels: greater influx: depolarization & hyperexcitation • In mammalian liver  IgE-Anaphylactic Shock

38. Case 4:

39. Case 5:

40. Any chemical not listed in a schedule which can produce rapidly in humans sensory irritation or disabling physical effects which disappear within a short time following termination or exposure

41. A toxic chemical and delivery system. • Biological and Toxin Weapons Convention (BTWC).