Toxicology Flashcards
Contrast the treatment of organophosphate or nerve gas poisoning with that of carbamate or herbicide intoxication.
organophosphate or malathion poisoning will inhibit acetylcholinesterase. some phosphastes target neuronal esterase and cause neurotoxicity/paralysis. Give atropine.
Sarin, Somin nerve gases should be treated with Pralidoxime (removes organophosphate from acetylcholinesterase)
Carbamate poisoning has short effects w/ spontaneous recovery
Herbicides (2,40dichlorophenoxyacetic) - GI symptoms, confusion, aggressiveness and metabolic acidosis. Give Sodium Bicarb to alkalinize. (control electrolytes like K and Ca loss)
Paraquat herbicide - free radical tissue damage. No antidote.
What is presentation of heavy metal poisoning?
Lead - decreased Ach release and Na/K ATPase inhibition. Low motiliity and water efflux. Slowed nerve conduction and lead anemia. Proximal tubule dysfunction. Encephalopathy.
Arsenic - derm changes, hyperpigmentation, palmar keratoses, malignant changes in all organs
Mercury - interstitial pneumonitis. Dequamative rash (acrodynia), paresthesias, nephrotic syndrome.
Iron - hematemesis, diarrhea, cellular toxicity to mitochond and low oxidative phosphorylation. Primarily affects liver, also heart, renal and lung, hematotox.
What is most frequent cause of intoxication?
took or given medication twice, followed by incorrect dosing and wrong medication taken/given.
What is most common therapy for intoxication?
decontamination only (almost 50% of the time)
What is general patient management for intoxication?
ABCDEFG
Airway, Breathing, Circulation, Disability-AVPU/Glasgow Coma scale, Dont Ever Forget Glucose, Get a set of basic observations
What is treatment for iron overdose?
deferoxamine
What is treatmetn for opiate overdose
naloxone
What is treatment for acetaminophen overdose?
N Aetylcysteine
What is treatment of digoxin overdose?
digibind + Mg
What is treatment of BNZ overdose?
flumazenil
What is essential when giving activated charcoal?
Protect the airway. Only give it if patient has ingested a potentially toxic amount of poison that is KNOWN to be absorbed by charcoal.
What is syrup of Ipecac?
emetic made from Cephaelis plant. Emesis withing 20 minutes that lasts 30-120 minutes.
What is ADE of ipecac?
drowsiness, abdominal pain, diarrhea.
High abuse potential and Chronic use causes cardiotoxicity
When should GI decontamination be used?
only when there is a life-threatening exposure
Patient comes in to ED with undifferentiated acute poisoning should you gastric lavage?
No. There is no benefit likely. Might cause GI perforation, hypoxia or aspiration. Likely the toxin has already passed duodenum
What can be used to clear toxic methanol, ethylene glycol, salicylates, lithium or sotalol levels from blood?
Hemodialysis. Only works for water soluble toxins with low molecular weight and low plasma protein binding.
What should be used to clear carbamazepine, phenobarbital, phenytoin or theophylline from blood?
hemoperfusion. Passage of blood thorugh absorptive cartridge that is usually charcoal. Good for substances highly bound to protein.
What is treatment for sympathomimetic overdose like cocaine, amphetamine, methamphetamine, decongestants (phenylpropanolamine, ephedrine, pseudoephedrine), caffeine, theophylline?
primary supportive.
Phentolamine, nitrates or Ca blockers for HTN
BNZ for agitation
What is absolutely contraindicated in someone who has OD on decongestants or other sympathomimetics?
absolutely no BB w/o alpha blocker. There will be unopposed alpha-stimulation
What is treatment for BB toxicity?
activated charcoal.
For bradycardia and hypoTN, give IV glucagon
For cardiotoxicity use high dose insulin and dextrose
Can give Na bicarbonate to correct membrane depression (from TCA poisoining)
Lipid emulsions
What is treatment of Ca channel blocker toxicity?
activated charcoal for hypoTN and bradycardia give IV Ca chloride or Ca gluconate to get Ca levels to 2x normal. (most useful because of its negative inotropic effects) Give epinephrine and glucagon Or High dose insulin +dextrose Lipid emulsion also
How does insulin and dextrose work for BB or CaB toxicity?
promotes uptake of lgucose, shifts K intracellularly, improves inotropy,
Increases myocardial metabolism and decreases FFA metabolism
What is toxidrome of isoniazid?
acute reduction in brain pyridoxal 5-phosphate, active Vitamin B6.
Results in low GABA levels and seizures.
Inhibits hepatic conversion of lactate to pyruvate causing lactic acidosis (compounds with seizures)
What is treatment for isoniazid overdose?
vitamin B6 (pyridoxine)
What are the phases of acetaminophen?
Phase 1 - 30min-4hrs patient will appear normal (minor anorexia, pallor, N/V, diaphoresis)
Phase 2- 24-48hrs Recovery, Right UQ pain from hepatic damage. PT time increased and decraesed renal function.
Phase 3 (3-5days) - hepatic necrosis, coag defects, jaundice, renal failure, hepatic encephalopathy, centrilobar necrosis
Phase 4- (4days-2weeks) - death or resolution
What can be used to determine extent of acetaminophen toxicity?
Rumack-Matthew Nomogram
What is toxidrome for salicylate poisoining?
uncoupled cellular oxidative phosphorylation.
Anaerobic metabolisma nd excessive production of lactic acid and heat that interfere with Krebs cycle enzymes.
Brainstem stimulted causing tachypnea.
Respiratory alkalosis, metabolic acidosis
Tachycardia, tinnitus, agitation, confustion, seizures, pulmonary edema, hyperthermia
What is metabolism of salicylates?
zero-order metabolism
How do you diagnose salicylate poisoining?
NOT by presentation. Must measure blood levels and high anion gap.
WHat is treatment for salicylate poisoining?
charcoal 10:1 weight ratio.
Glucose to prevent cerebral hypoglycemia
For metabolic acidosis give IV Na Bicarb
Alkinalize the urine to enhance renal excretion.
Add potassium chloride to IV
Hemodialysis if severe metabolic acidosis or altered mental status
Which drugs cause high anion gap acidosis?
MUDPILES CAT
methanol/metformin, Uremia, DKA, Iron, INH, Ibuprofen, LActic acidosis, ehtylene glycol, salicylates, cyanide, alcohol or acids (valproate), toluene ror theophylline
What is cyproheptadine?
antihistamine with anti-serotonin activity