Specific Toxins
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Transcript of Specific Toxins
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Specific Toxins
Part II
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Infectious Agents
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Bacterial Food Infection/Poisoning
• Signs/Symptoms – Nausea, vomiting– Abdominal cramps– Diarrhea– History of eating same foods in same place
as others with similar symptoms
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Bacterial Food Infection/Poisoning
• Management– Prevention
• Cook thoroughly• Keep hot foods hot• Keep cold foods cold
– Replace lost fluids, electrolytes– Antiemetic agents
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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
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Botulism
• Signs/Symptoms– GI upset– Dry mouth – Double vision (diplopia)– Drooping eyelids – Slurred speech– Descending paralysis - respiratory arrest
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Botulism
• Management– Support ABC’s– Antitoxin
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Common Cardiac Medications
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Beta Blockers
• Signs/Symptoms– Bradycardia– Hypotension, shock– AV blocks– Prolonged QRS complex– Heart failure– Bronchospasms
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Beta Blockers
• Management– ABC’s– Oxygen– Bronchospasms
• Inhaled 2 agents
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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
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Calcium Channel Blockers
• Signs/Symptoms– Bradycardia– Hypotension, shock– AV blocks– Heart failure– QRS prolongation does NOT occur
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Calcium Channel Blockers
• Management– Calcium reverses decrease in contractility– Fluid infusion increases BP
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Digitalis
• Signs/Symptoms– Central Nervous System
• Headache• Irritability• Psychosis• Yellow-green vision
– Gastrointestinal• Anorexia• Nausea, vomiting
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Digitalis
• Signs/Symptoms– Cardiac
• Atrial tachycardia with block• Non-paroxysmal junctional tachycardia• PACs, PJCs, PVCs
Tachyarrhythmias + Blocks =>Digitalis toxicity
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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)
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Digitalis
• Precautions– Cardioversion, pacing attempts may cause VF– Vagal stimulation may cause bradycardia, AV
blocks– Calcium may worsen ventricular arrhythmias
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Theophylline
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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)
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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.
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Theophylline
• Mild Toxicity (20-40 mcg/ml)– Gastrointestinal discomfort, vomiting, diarrhea
• Most common sign of toxicity • 60-100% of patients experience vomiting
– Restlessness, irritability
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Theophylline
• Moderate Toxicity (40 - 100mcg/ml)
– Wakefulness– Mild Sinus Tachycardia– Tachydysrhythmias– Increased Blood Pressure– Decreased blood pressure
– Hyperthermia– Albuminuria– Dehydration– Hematemesis– Manic behavior– Hallucinations
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Theophylline
– Dysrhythmias– VF threshold reduction– Seizures
• Mechanism unknown• Indicate poor outcome• May lead to rhabdomyolysis,
renal failure, permanent neurologic sequelae
• On EEG seizure is continuous
• Severe Toxicity (>100mcg/ml)
– Dehydration– Metabolic
abnormalities– Hyperthermia– Coma– DEATH
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Theophylline
• Management– ABCs
• Provide O2
• Intubate, if necessary• Support vital signs• Control seizures, arrhythmias
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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
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Theophylline
• Management– Sinus tachycardia
• Rarely requires treatment
– Supraventricular tachycardia • Verapamil• Cardiospecific beta blockers
– Ventricular ectopy• Lidocaine
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Theophylline
• Management– Hypotension
• Correct SVT, if present• Fluids• Dopamine• Norepinephrine
– Seizures• Valium• Phenytoin• Phenobarbitol• General anesthesia
for status seizures
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Tricyclic Antidepressants
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TCAs
• Examples– Elavil– Tofranil– Sinequan– Surmontil– Vivactil
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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
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TCAs
• Mechanism of Toxicity: CNS– Anticholinergic effects: sedation, coma– Inhibition of NE, serotonin re-uptake: seizures
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TCAs
• Three major toxic syndromes– Anticholinergic effects– Cardiovascular effects– Seizures
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Anticholinergic Effects
• Sedation, coma, delirium• Dilated pupils• Dry skin, mucous membranes• Tachycardia• Decreased bowel sounds• Urinary retention• Myoclonic jerking (often mistaken for seizures)
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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
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Seizures
• Common with TCA toxicity• Recurrent or persistent• Combined with diminished sweating can lead to
– Severe hyperthermia, – Rhabdomyolysis– Brain damage– Multisystem failure– DEATH
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Death
• Usually occurs within hours due to :– Ventricular fibrillation– Intractable cardiogenic shock– Status epilepticus with hyperthermia
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TCAs
• The three C’s
– Coma
– Convulsions
– Cardiac arrhythmias
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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
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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
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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
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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
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TCAs
• Management of Toxicity– Hypotension
• Fluids• Vasopressors
– Seizures • Diazepam, phenobarbital. • If these do not work, paralyze patient
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Iron
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Iron
• Incidence (1995 AAPCC Annual Report)– 28,039 Exposures– 378 moderate, major effects– 3 deaths
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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
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Iron
Signs and Symptoms
Occur in five stages
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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
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Stage II
• 6-24 hours post ingestion
• Sometimes absent in severely poisoned patients
• Patient seem to improve; feels, looks better
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Stage III
• 6-48 hours post ingestion
• Metabolic, systemic derangement – Cardiovascular collapse– Coma– Seizures– Coagulopathy– Pulmonary edema
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Stage IV
• 2-7 days post ingestion– Hepatotoxicity (jaundice) – Coagulopathy– Metabolic acidosis– Renal insufficiency
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Stage V
• 1-8 weeks post ingestion
• Primarily delayed GI complications– Gastric/duodenal fibrosis– Scarring of pylorus– Intestinal obstruction
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Iron
• Overdose Treatment– Decontamination
• Lavage useful if done within first 60 minutes post ingestion
• Iron does NOT bind to activated charcoal
– Whole bowel irrigation
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Iron
• Overdose Treatment– Desferal ( desferoximine )
• Chelating agent • Binds free iron, complex is excreted renally• “Vin rose’” urine color depending on urine pH
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Isoniazid
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Isoniazid
• Drug of Choice for – Tuberculosis treatment– Tuberculosis prophylaxis
• Used in prevention of opportunistic Infections in HIV infected patients
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Isoniazid
• Mechanisms of Toxicity: Acute– Neurological
• Competes with pyridoxal 5-phosphate (vitamin B6) for enzyme glutamic acid decarboxylase
• Results in decreased GABA levels
• Causes seizures
– Hepatic• Inhibits hepatic conversion of lactate to pyruvate
• Produces lactic acidosis.
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Isoniazid
• Mechanisms of Toxicity: Chronic– Peripheral neuritis (thought to be related to
competition with pyridoxine)– Systemic Lupus Erythematosus – Hepatic Injury
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Isoniazid
• Toxic Doses– Acute Ingestion: As little as 1.5 gms– Chronic Use: 10-20% incidence of hepatic
toxicity when dose is 10mg/kg/day
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Isoniazid
• Acute Overdose– Slurred Speech– Ataxia– Coma– Seizures (within 30 - 60 minutes)– Profound anion gap metabolic acidosis
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Isoniazid
• Management– ABCs– Treat coma, seizures, metabolic acidosis
accordingly.
– Pyridoxine ( vitamin B6 )• One gram for each gram of isoniazid ingested• If amount unknown give at least 5gm IV• If amount on hand is insufficient, give what is
available and then give diazepam
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Carbon Monoxide
• Produced by incomplete combustion (autos, home heaters)
• Colorless, odorless, tasteless
• Binds to hemoglobin - blocks oxygen carrying capacity
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Carbon Monoxide
• Signs/Symptoms– Headache, N/V, ringing in ears,
incontinence, seizures, coma, pulmonary edema
– Cherry-red skin - usually a terminal event– Suspect with a lot of “sick” patients at one
location
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Organophosphates
• Pathophysiology– Block cholinesterase. – Cause build-up of acetylcholine in
synapses. – Produce cholinergic crisis.
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Organophosphates• Signs and Symptoms
– Salivation– Lacrimation– Urination– Defecation– Gl Cramping– Emesis
– Pin-point pupils– Bradycardia– Bronchospasms– Muscle twitching– Weakness– Ventilatory failure
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Organophosphates
• Management– 100% oxygen, assist ventilations– IV tko– Monitor ECG– Atropine 1mg IV, 2mg IM. Repeat until
atropinized– Pulmonary edema is non-cardiogenic in
origin; avoid lasix, morphine
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Anhydrous Ammonia
• Signs/Symptoms– Acute pulmonary edema– Laryngeal edema– Ventricular arrhythmias/hypotension– Ocular necrosis - blindness– Partial and full thickness skin burns
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Anhydrous Ammonia• Management
– SCBA/Protective equipment required!– Delay entry until equipment available
– Wash patient with large amounts of H2O
– ABC’s, O2, assist ventilations
– Intubate/suction lower airway PRN– Assist ventilation/consider PEEP– Irrigate eyes– Admit/observe for delayed effects