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Specific Toxins

Specific Toxins. Part II. Infectious Agents. Bacterial Food Infection/Poisoning. Signs/Symptoms Nausea, vomiting Abdominal cramps Diarrhea History of eating same foods in same place as others with similar symptoms. Bacterial Food Infection/Poisoning. Management Prevention

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Specific Toxins

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  1. Specific Toxins Part II

  2. Infectious Agents

  3. Bacterial Food Infection/Poisoning • Signs/Symptoms • Nausea, vomiting • Abdominal cramps • Diarrhea • History of eating same foods in same place as others with similar symptoms

  4. Bacterial Food Infection/Poisoning • Management • Prevention • Cook thoroughly • Keep hot foods hot • Keep cold foods cold • Replace lost fluids, electrolytes • Antiemetic agents

  5. Botulism • Pathophysiology • Neurotoxin from Clostridium botulinum • Produced in anaerobic environment at pH >4.6 • Boiling will destroy toxin • Toxin binds to cholinergic nerve terminals; Blocks acetylcholine release

  6. Botulism • Signs/Symptoms • GI upset • Dry mouth • Double vision (diplopia) • Drooping eyelids • Slurred speech • Descending paralysis - respiratory arrest

  7. Botulism • Management • Support ABC’s • Antitoxin

  8. Common Cardiac Medications

  9. Beta Blockers • Signs/Symptoms • Bradycardia • Hypotension, shock • AV blocks • Prolonged QRS complex • Heart failure • Bronchospasms

  10. Beta Blockers • Management • ABC’s • Oxygen • Bronchospasms • Inhaled 2 agents

  11. Beta Blockers • Management • Bradycardia • Atropine 0.5 - 1.0 mg • Glucagon 5mg every 30’ • Cardiac pacing • Hypotension • Glucagon 5mg every 30’ • Dopamine 5mcg/kg/min

  12. Calcium Channel Blockers • Signs/Symptoms • Bradycardia • Hypotension, shock • AV blocks • Heart failure • QRS prolongation does NOT occur

  13. Calcium Channel Blockers • Management • Calcium reverses decrease in contractility • Fluid infusion increases BP

  14. Digitalis • Signs/Symptoms • Central Nervous System • Headache • Irritability • Psychosis • Yellow-green vision • Gastrointestinal • Anorexia • Nausea, vomiting

  15. Digitalis • Signs/Symptoms • Cardiac • Atrial tachycardia with block • Non-paroxysmal junctional tachycardia • PACs, PJCs, PVCs Tachyarrhythmias + Blocks =>Digitalis toxicity

  16. Digitalis • Management • ABC’s, oxygen • Check electrolytes, correct hypo/hyperkalemia • Atropine: bradycardia with hypotension • Dilantin: ectopy • Lidocaine/magnesium sulfate: ventricular ectopy • Digtalis immune Fab Fragments (Digibind)

  17. Digitalis • Precautions • Cardioversion, pacing attempts may cause VF • Vagal stimulation may cause bradycardia, AV blocks • Calcium may worsen ventricular arrhythmias

  18. Theophylline

  19. Theophylline • Actions • Relaxes bronchial smooth muscle • Stimulates respiration • Stimulates cardiovascular constriction • Stimulates gastric acid secretion • Augments cardiac inotrophy • Relax uterine smooth muscle • Diuresis (Stronger than caffeine but shorter duration)

  20. Theophylline • Narrow therapeutic index • Leading cause of drug induced seizures • Seizures can occur with levels slightly over 20 mcg/ml. • Common causes of toxicity • Large single dose • Accidental accumulation secondary to inadvertent overmedication.

  21. Theophylline • Mild Toxicity (20-40 mcg/ml) • Gastrointestinal discomfort, vomiting, diarrhea • Most common sign of toxicity • 60-100% of patients experience vomiting • Restlessness, irritability

  22. Theophylline • Moderate Toxicity (40 - 100mcg/ml) • Hyperthermia • Albuminuria • Dehydration • Hematemesis • Manic behavior • Hallucinations • Wakefulness • Mild Sinus Tachycardia • Tachydysrhythmias • Increased Blood Pressure • Decreased blood pressure

  23. Theophylline • Severe Toxicity (>100mcg/ml) • Dehydration • Metabolic abnormalities • Hyperthermia • Coma • DEATH • Dysrhythmias • VF threshold reduction • Seizures • Mechanism unknown • Indicate poor outcome • May lead to rhabdomyolysis, renal failure, permanent neurologic sequelae • On EEG seizure is continuous

  24. Theophylline • Management • ABCs • Provide O2 • Intubate, if necessary • Support vital signs • Control seizures, arrhythmias

  25. Theophylline • Management • Decontamination • Lavage, activated charcoal • Due to possible rapid onset of seizures, emesis NOT recommended. • Whole bowel irrigation may be necessary if Theophylline levels continue to rise secondary to sustained release preparations. • Endoscopic removal of bezoar may be necessary if levels continue to rise, patient’s condition deteriorates

  26. Theophylline • Management • Sinus tachycardia • Rarely requires treatment • Supraventricular tachycardia • Verapamil • Cardiospecific beta blockers • Ventricular ectopy • Lidocaine

  27. Theophylline • Management • Hypotension • Correct SVT, if present • Fluids • Dopamine • Norepinephrine • Seizures • Valium • Phenytoin • Phenobarbitol • General anesthesia for status seizures

  28. Tricyclic Antidepressants

  29. TCAs • Examples • Elavil • Tofranil • Sinequan • Surmontil • Vivactil

  30. TCAs • Mechanism of Toxicity: Cardiovascular • Alpha-adrenergic blockade: vasodilation • Anticholinergic effects: tachycardia, mild hypertension • Quinidine-like effects: myocardial depression • Inhibition of sodium channels: conduction defects • Metabolic or respiratory acidosis may contribute to cardiotoxicity by inhibition of fast sodium channels

  31. TCAs • Mechanism of Toxicity: CNS • Anticholinergic effects: sedation, coma • Inhibition of NE, serotonin re-uptake: seizures

  32. TCAs • Three major toxic syndromes • Anticholinergic effects • Cardiovascular effects • Seizures

  33. Anticholinergic Effects • Sedation, coma, delirium • Dilated pupils • Dry skin, mucous membranes • Tachycardia • Decreased bowel sounds • Urinary retention • Myoclonic jerking (often mistaken for seizures)

  34. Cardiovascular Effects • Arrhythmias, abnormal conduction, hypotension • Prolongation of PR, QRS, QT intervals (QRS > 0.12 is a good predictor of toxicity) • Various degrees of AV block • Hypotension caused by vasodilatation • Cardiogenic shock • Pulmonary edema

  35. Seizures • Common with TCA toxicity • Recurrent or persistent • Combined with diminished sweating can lead to • Severe hyperthermia, • Rhabdomyolysis • Brain damage • Multisystem failure • DEATH

  36. Death • Usually occurs within hours due to : • Ventricular fibrillation • Intractable cardiogenic shock • Status epilepticus with hyperthermia

  37. TCAs • The three C’s • Coma • Convulsions • Cardiac arrhythmias

  38. TCAs • Overdose Evaluation • Most have narrow therapeutic index • Doses <10x therapeutic daily dose may produce severe poisoning • 10-20 mg/kg can be life threatening • In children one tablet can cause death

  39. TCAs • Management of Toxicity • ABCs • Decontamination (Lavage even up to 4-6 hours post ingestion may be useful due to decreased GI motility) • Activated charcoal

  40. TCAs • Management of Toxicity • Sodium Bicarbonate (1-2 mEq/kg) • Maintain pH of 7.45 to 7.55 • Protects cardiac membrane, corrects acidosis • Hyperventilation to induce respiratory alkalosis can work for short time

  41. TCAs • Management of Toxicity • Pacing for bradyarrhythmias, high-degree AV block • Overdrive pacing for Torsades des pointes • Do NOT use type 1a or 1c antiarrhythmic agents for V-tach; can aggravate cardiotoxicity

  42. TCAs • Management of Toxicity • Hypotension • Fluids • Vasopressors • Seizures • Diazepam, phenobarbital. • If these do not work, paralyze patient

  43. Iron

  44. Iron • Incidence (1995 AAPCC Annual Report) • 28,039 Exposures • 378 moderate, major effects • 3 deaths

  45. Iron • Overdose Evaluation • How much elemental Fe could have been ingested (mg/kg)? • < 20mg/kg: not considered toxic, can be left at home • 20-60mg/kg: mild to moderate toxicity, some treatment required • > 60mg/kg: high toxicity; hospitalization required

  46. Iron Signs and Symptoms Occur in five stages

  47. Stage I • 30 minutes-6 hours post ingestion • GI irritation, due to iron’s corrosive effects • Nausea, vomiting • Epigastric pain • GI bleeding • Drowsiness • Hypotension • Metabolic acidosis • Leukocytosis • Hyperglycemia

  48. Stage II • 6-24 hours post ingestion • Sometimes absent in severely poisoned patients • Patient seem to improve; feels, looks better

  49. Stage III • 6-48 hours post ingestion • Metabolic, systemic derangement • Cardiovascular collapse • Coma • Seizures • Coagulopathy • Pulmonary edema

  50. Stage IV • 2-7 days post ingestion • Hepatotoxicity (jaundice) • Coagulopathy • Metabolic acidosis • Renal insufficiency

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