Toxicology Flashcards
Prompt Coma Treatment with Suspected Overdose
100 mg Thiamine IM/IV with suspected alcoholism
50 mL glucose with 50% IV solution
0.4-2.0 mg IV Narcan - 0.8 is stat
Toxicology Initial Keys
Maintain circulation, get IV access
Cardiac monitoring and pulse ox for all
Consider quick reversal methods
Collect as much history as possible and correlate with PE and clinical presentation
Decontamination
Emesis only occurs in patients with intact gag reflex
Emesis efficacy is decreased >1 hour ingestion
Ipecac syrup with water to induce vomiting - best with tylenol
Activated charcoal to bind toxins - effectiveness decreased by ipecac
- only binds to positive ions, depends on the medication
Gastric Lavage - rarely used, not recommended; faster than ipecac
Poisons not bound by Activated Charcoal - PAIL
Potassium
Alcohols
Iron
Lithium
First-Order Kinetics
Zero-Order Kinetic
First-Order Kinetics: A fixed percentage of toxin removed per unit of time
Zero-Order Kinetics: A fixed amount of toxin is removed per unit of time
Hemodialysis vs Hemoperfusion
Hemodialysis: toxin must be water-soluble and not highly protein bound
Hemoperfusion: Drug/toxin is in direct contact with absorbent material - high MW, poor water solubility, and high binding are not limiting factors
- Commonly associated with thrombocytopenia, will not correct electrolyte imbalance or pH
Antidotes:
Acetaminophen
Anticholinergics
Benzodiazepines
Acetaminophen: Acetylcysteine increases glutathione reserves
Anticholinergics: Physostigmine
Benzodiazepines: Flumazenil - GABA antagonist, may cause seizure w/ rapid infusion - rarely used
Antidotes:
Cyanide
Methanol/Polyethylene Glycol
Narcotics
Cyanide: Sodium nitrite and thiosulfate
Methanol/Polyethylene Glycol: Ethanol drip
Narcotics: Naloxone
MUD PILES
For anion gap metabolic acidosis
Methanol
Uremia
Diabetic Ketoacidosis
Paraldehyde
Infection
Lactic Acidosis
Ethylene Glycol
Salicylates
Osmolar Gap
Used to determine what intoxicant pt used
2(Na) + Glu/18 + BUN/2.8
Measured - calculated = osmolar gap (normal <10)
w/ gap >30 - think different forms of alcohol
Ethanol is the MC cause
Acetaminophen Overdose
Max dose is 3 grams; 6 grams is overdose
Hepatotoxic metabolite - accumulates in liver w/ delayed effect
>140 mg/kg is toxic dose; lower w/ chronic liver disease or alcoholism
Treat w/in 16 hours to reduce morbidity and mortality
Treatment: Activated charcoal with Acetylcysteine therapy (140 mg/kg) - binds metabolite
Cocaine/Amphetamine
CNS Stimulants - cause sympathetic hyperactivity
Significant vasoconstriction, HTN, bradycardia
-May result in ventricular arrhythmias, rhabdomyolysis, myoglobinuria
Peak effects w/in 1-2 hours
Cocaine/amphetamine Overdose Treatment
GI decontamination
Diazepam for agitation/psychosis and seizures
Do not acidify the urine
Nitroprusside for HTN - watch for cyanide buildup
Anticholinergics
Atropine, Scopolamine, Belladonna, antihistamines, TCAs, mushrooms
Block central and peripheral cholinergic receptors
“Hot as a hare, red as a beet, dry as a bone, blind as a bat, and mad as a hatter”
Anticholinergic Overdose Treatment
Physostigmine reserved for severe symptoms
-Never w/ TCA overdose, asthma, or bowel/bladder obstruction
GI decontamination - sx may last awhile due to anticholinergic effect on bowel function
Supportive - may need external pacing
Arsenic Toxicity
Insecticides, rodenticides, wood preservatives, Shellfish, Gas
Arsenic is well absorbed, binds to tissue proteins and accumulates
Lethal dose in adult = 100-200 mg
Present with peripheral neuropathy, skin manifestations, and garlicky odor on breath, periorbital edema, with GI upset
Arsenic Treatment
24 hour arsenic levels to monitor chelation therapy response
-may be false positives w/ shellfish ingestion
Treatment: Chelation therapy w/ chronic, GI decontamination with chelation for acute
Gas inhalation: transfusion with hydration to prevent renal hemoglobin deposition
-Chelation has no value w/ inhalation
Digitalis Toxicity
Cardiac glycoside - enhance contractility, slow AV conduction, enhance automaticity
Anorexia, N/V/D, abdominal pain, blurred vision and color vision disturbance
EKG shows 3rd degree AV block, bradycardia, ventricular ectopy, paroxysmal A-tach with AV block
Acute ingestions associated w/ hyperkalemia
Digitalis Toxicity Treatment
Glucose + insulin w/ severe hyperkalemia (>7) - do not use CaCl - will kill pt
Bradycardia/AV block - atropine, transcutaneous pacing
Ventricular ectopy - lidocaine drip
Dialysis or hemoperfusion is not effective
Digibind (Fab fragment antibodies) - bound dig is not active
Mushroom Toxicology
Severe GI, muscarinic sx, hallucinations, anticholinergic effects - depends on mushroom type and toxin
Treatment is mainly supportive and targeted at whatever effects toxin has
Psilocybin mushrooms are MC seen poisoning - hallucinogens
Clonidine Overdose
Mimics an opioid overdose - pinpoint pupils, respiratory depression
Do not respond to naloxone
Propoxyphene overdose is also resistant to naloxone
Organophosphate Toxicity
Cholinesterase inhibitors - bug sprays, chemical warfare
Inhibit cholinesterase - allow ACh accumulation at muscarinic and nicotinic neuromuscular junction
Rapidly absorbed through skin, GI, respiratory
DUMBELS for symptoms
May have profound bradycardia (muscarinic) or tachycardia (nicotinic)
DUMBELS
Diarrhea
Urination
Miosis
Bronchospasms
Excitation
Lacrimation
Salivation
Organophosphate Toxicity Treatment
Decontamination
Aggressive airway management - secretions and bronchospasm
Atropine IV - large doses
Pralidoxime - competitive binder to ACh
