MANAGEMENT OF ACUTE POISONING

1. MANAGEMENT OF ACUTE POISONING Kent R. Olson, MD Medical Director California Poison Control System San Francisco Division

3. Lessons from history • A young princess ate part of an apple given to her by a wicked witch • She was found comatose and unresponsive, as if in a deep sleep • Airway positioning and mouth to mouth ventilation were performed, and she recovered fully

4. Lesson: Best antidote is good supportive care (Love’s first kiss)

5. Young woman found unconscious, several empty pill bottles nearby Unresponsive to painful stimuli Shallow breathing Case 1:

6. Airway Breathing Circulation Dextrose, drugs, decontamination Initial management: ABCDs

7. Risks: Floppy tongue can obstruct airway Loss of protective reflexes may permit pulmonary aspiration of gastric contents Major cause of morbidity in poisoned patients Airway issues

8. “Gag” reflex Indirect measure May be misleading Can stimulate vomiting Alternatives Assessing the airway

9. Assess visually pCO2 reflects ventilation - ABG useful pulse oximetry provides convenient, noninvasive evaluation of O2 saturation Breathing

10. pO2 measures dissolved oxygen can be normal despite abnormal hemoglobin states, eg COHgb, MetHgb Pulse oximetry also fails to detect CO poisoning Pitfalls

11. Endotracheal intubation Protects airway Allows for mechanical ventilation Reverse coma? Naloxone: note T½ = 60 min Flumazenil? Interventions

12. “A stroke is never a stroke until it’s had 50 of D50” – Dr. Larry Tierney, 1976 “Well, you could just do an Accuchek”- ibid, 2002 Give Thiamine 100 mg IM or in IV Don’t forget GLUCOSE

13. The patient has no gag reflex, and does not resist intubation. She remains unconscious and on a ventilator overnight Awakens and extubated the next day Dx: mixed sedative drug overdose Case, continued…

14. 47 year old man calls 911, suicidal BP 70/50, HR 50/min Junctional rhythm Hx: uses an antihypertensive Case 2

16. Pump working? Enough volume (is it primed)? Adequate resistance (no leaks)? Circulation = plumbing

17. Hypovolemia? IV fluid challenge Pump? Dopamine Inadequate vascular resistance? Norepinephrine, phenylephrine Management of Hypotension

18. Diuretics Beta blockers Calcium channel blockers ACE Inhibitors Centrally acting agents Vasodilators Antihypertensives

19. Bad ODs!! Low Toxic:Therapeutic ratio High mortality Calcium channel blockers

20. Decreased Automaticity & Conduction Negative Inotropic Effects Dilated Vascular Smooth Muscle SVR HR CO AV Block SHOCK

21. Calcium: most effective High doses may be needed Glucagon – variable results Insulin plus glucose? (experimental) Calcium antagonists - treatment

22. An 18 month old takes some of his grandmother’s “sleeping pills” Brought to the ER after a seizure HR 150/min Pupils dilated, skin flushed, mucous membranes dry Case 3:

23. Amphetamines/cocaine Tricyclic and other antidepressants Isoniazid (INH) Diphenhydramine Alcohol withdrawal Many others . . . Common causes of seizures

24. 30 minutes later, the ECG shows:

25. Anticholinergic syndrome Seizures Cardiotoxicity Tricyclic antidepressants

26. Stop the seizures Benzodiazepines, phenobarbital Treat cardiotoxicity Sodium bicarbonate 1 mEq/kg IV IV fluids Dopamine and/or NE TCA overdose treatment(similar tox possible w/ massive diphenhydramine)

27. Case 4: metabolic acidosis • Young man had a seizure at home • In ED: obtunded, another seizure • pH 6.94, pCO2 32 • Recent immigrant, lives with extended family • Uncle being treated for TB

28. Metabolic Acidosis: MUDPILES • Methanol • Uremia • DKA • Phenformin (whaa?) • Isoniazid, Iron • Lactic acidosis • Ethylene Glycol • Salicylate

29. Isoniazid overdose • Reduces brain pyridoxal 5-phosphate, a cofactor for glutamic acid decarboxylase: • Seizures common; acidosis often severe • Antidote: Pyridoxine (Vitamin B-6) (excitatory) (inhibitory)  GABA Glutamate  GAD

30. Case 5: another acidosis • 44 year old man, obtunded • BP 110/80 HR 110 RR 24 • pH 7.47 pCO2 22 pO2 92 • Na 140 K 3.8 Cl 104 HCO3 18 • EtOH 0.18 gm/dL (180 mg/dL)

31. Salicylate poisoning • Typical mixed acid-base disturbance • Respiratory alkalosis • Metabolic acidosis • Large OD or enteric coated tablets may delay peak level • Treatment: • Urinary alkalinization, hemodialysis

32. Case 6: more acidosis • 30 yo woman found comatose • T 92 F, pH 6.9 • Na 147, K 4.9, Cl 105, Bicarb 5 (AG 37) • Glucose 166, BUN 16, Cr 1.5 • Measured Osm 331 (calculated 308) • EtOH: none detected

33. The Osmolar Gap Osm = 2 (Na) + BUN/2.8 + Glucose/18 Gap = Measured - Calculated Osm = 0 + 5 • Common causes of Osm Gap: • Ethanol • Methanol & Ethylene Glycol • Other alcohols, also aldehydes, ketones

34. METHANOL ELEVATED OSMOLAR GAP FORMALDEHYDE ANION GAP ACIDOSIS FORMIC ACID

35. Methanol or Ethylene Glycol: • Elevated Osm Gap • Anion gap • Low lactate, does not account for gap • Anion gap may be absent early after OD • Other clues (may be unreliable): • Methanol: blindness, visual disturbance • EG: urine crystals, fluorescence

36. Methanol or Ethylene Glycol: • Main DDx: alcoholic ketoacidosis • Anion and Osm gaps • Low lactate • Clues to AKA: • Gets better quickly w/ IV fluids, dextrose • [Ketones] +/- (mainly -hydroxybutyrate)

37. Case 7: now we’re cookin’ • 24 year old man with Hx depression • Agitated, confused • BP 110/70 HR 120 RR 20 T 40.4 C • Muscle tone increased, LE clonus • Tox screen negative for cocaine, amphetamines

38. Drug-induced Hyperthermia • Heat Stroke • Malignant Hyperthermia • Neuroleptic Malignant Syndrome • Serotonin Syndrome

39. Drug-induced “heat stoke” • Altered judgment leads to excessive sun/heat exposure • Anticholinergic drugs prevent sweating • Excessive muscle hyperactivity from seizures, or from extreme agitation

40. Malignant hyperthermia • Rare, familial myopathy • Triggered by general anesthesia • Succinylcholine • Inhalational agents (eg, Halothane) • Muscle rigidity, hypermetabolic state • Treatment: dantrolene

41. Neuroleptic Malignant Syndrome • Patient on dopamine-blocking drugs • Haloperidol classic cause • Also with newer agents (eg, clozapine) • Rigidity (lead-pipe) • Autonomic instability • Hyperthermia

42. Serotonin Syndrome • Current “hot” diagnosis • Serotonin-enhancing Rx • SSRIs in OD or multiple combos • MAOI + serotonin-ergic drug • Hypertonicity/clonus (esp. lower extr.) • Autonomic instability • Hyperthermia

43. Hyperthermia treatment • Act quickly! • Remove clothing spray and fan • Sedation and anticonvulsants PRN • Neuromuscular paralysis if T >40 C • Dantrolene if NM paralysis ineffective • Consider bromocriptine, cyproheptadine

44. One more common one • A 17 year old boy takes a bottle of “aspirin” after he gets his SAT score • Next morning, he is vomiting • In the ED, normal vital signs • Aspirin (salicylate) = negative

45. Acetaminophen • Very common overdose • May be overlooked • “It’s just aspirin” (OTC’s can’t kill you..?) • Hidden ingredient in many drug combos • No specific findings after OD • Delayed illness/lab abnormalities

46. Acetaminophen (APAP) P-450 Sulfation (non toxic) Glucuronidation (non toxic) ~ 5% NAPQI NAC ++ Glutathione + NAPQI nontoxic product Liver cell damage

47. N-acetylcysteine (NAC) • Start within 8 hrs if possible • Vomiting often interferes w/oral dosing • Antiemetics (ondansetron, etc) • Can dribble in by NG tube • IV form now available (Acetadote™) • Caution: hypotension w/rapid infusion

48. Goal: reduce systemic absorption Induce vomiting? Pump the stomach? Activated charcoal Gut decontamination after OD

49. Easy to perform, butnot very effective Contraindicated: Comatose/convulsing Ingested corrosive or hydrocarbon Bottom line: nobody uses it anymore Ipecac-induced emesis

50. Cooperation not required MD sense of “control” Punitive value? Pumping the stomach