CR - toxicologic disorders Flashcards
Clinical presentation: a 23 year old male presents with an increased anion gap metabolic acidosis. Which etiology is likely with the finding of calcium oxalate crystals in the urine?
Ethylene glycol poisoning
Metabolism of ethylene glycol results in production of the toxic metabolite oxalic acid which is a major contributor of the metabolic acidosis and Ca oxalate which forms intrarenal crystals
Ethylene glycol -> glycoaldehyde -> glycolic acid -> oxalic acid -> calcium oxalate crystals
In patients with propranolol overdose, which drug may produce dramatic improvement in heart rate and blood pressure?
Glucagon
Glucagon activates adenylate cyclase in myocardial cells, which bypasses impaired beta blockade and thus increasing inotropy and chronotropy. Vomiting can be caused by esophageal sphincter relaxation, therefore airway protection should be considered. Other side effects: nausea, hyperglycemia, hypokalemia, and allergic reactions.
A patient with a history of stage 3 CKD and multiple prior pulmonary embolisms presents to the ED for acetaminophen overdose. What labs need to be watched in this patient?
The patient is likely on Warfarin, which is hepatically eliminated. In the setting of liver injury from APAP, INR should be monitored for supratherapeutic levels. Supratherapeutic INRs should be treated appropriately, depending on if the patient is bleeding or not, with PCC and vitamin K
For what drug ingestions would you alkalanize the urine?
Salicylates
Initial IV fluid resuscitation via sodium bicarbonate with a goal serum pH of approximately 7.5. Once the urine has been alkalinized and urine output is adequate, potassium may be required as hypokalemia is common
Withdrawal from which substance produces the distinctive clinical findings of yawning, lacrimation, and piloerection?
Opioids
Within hours of opioid withdrawal, symptoms start that may include yawning, lacrimation, rhinorrhea, diaphoresis, and myalgias progressing to piloerection, mydriasis, abdominal pain, and GI symptoms with peak effects at 72 hours. Use the COWS score to assess for the patient’s stage of withdrawal and appropriateness for treatment with buprenorphine or methadone.
What are the features of Wernicke encephalopathy and what is the treatment?
Encephalopathy, ataxia, and oculomotor dysfunction
The treatment is daily IV thiamine until a normal diet is resumed:
Adult dosing - 100 mg IV
Pediatric dosing - 5-10 mg IV
Clinical presentation: a 21 year old male presents with nystagmus and extremely bizarre aggressive behavior. What is the diagnosis?
Phencyclidine (PCP) toxicity
The nystagmus may be horizontal, vertical, or rotary. Additional signs and symptoms vary widely and may include: hypertension, tachycardia, hyperthermia, hallucinations, euphoria, disinhibition, psychosis, violent behavior, catatonic state, and writhing. Mydriasis or miosis may be present.
What are the features of korsaakoff’s psychosis (aka alcohol induced persisting amnestic disorder)?
New antero/retrograde amnesia, confabulation, confusion, apathy
Treatment: IV thiamine always prior to glucose.
Glucose prior to thiamine can precipitate Wernicke’s encephalopathy
What is the appropriate disposition for a child who ingested a petroleum distillate but demonstrates no signs or symptoms of toxicity?
Observation for 6 hours
Petroleum distillate is a type of hydrocarbon. Symptoms typically depend on the specific substance but a major side effects is aspiration pneumonitis. Treatment is typically supportive.
Which type of caustic ingestion is worse, acid or alkali
Alkali
Hydroxide ions quickly and easily penetrate tissues, causing protein denaturation and lipid saponification. The liquefaction necrosis of alkali ingestion penetrates deeper than the coagulation necrosis of acid ingestion.
What is the treatment of organophosphate poisoning (sarin, soman, tabun, VX)?
What is the endpoint of treatment?
Atropine
- Adult 2mg IV q 5-15 minutes PRN
- child - 0.05 mg/kg q15 minutes PRN
Pralidoxime
- Starting dosages - adults 1-2 gm IV
Child 20-50 mg/kg IV
Treatment endpoint is control of tracheobronchial secretions. Consider early endotracheal intubation as atropine does not reverse muscle weakness
Intoxication with which drugs of abuse may cause live threatening hyperthermia
Cocaine
Methamphetamines (MDMA, ecstasy, molly)
Bath salts
For acutely agitated patients, benzodiazepines are the treatment of choice. Haloperidol, droperidol, and chlorpromazine may lower the seizure threshold and contribute to hyperthermia.
A glass etcher spilled hydrofluoric acid on himself while cutting glass.
What is the treatment?
What electrolyte abnormalities may be seen?
Topical or SQ injection of calcium gluconate for small BSA
IV/IA calcium gluconate for large BSA or oral ingestion.
Hypocalcemia and hyperkalemia can be life-threatening
What is the major hazard of barbiturate abuse?
Unintentional overdose
Barbiturates abuse does not lead to tolerance of its toxic effects. As larger doses are taken, the greater the likelihood of an unintentional overdose. Unlike tolerance, dependence occurs when a person feels they need a substance to function. Addiction is a brain disorder where a substance must be used because they require it both mentally and physically
What are the signs of benzodiazepine toxicity?
CNS depression, ranging from mild drowsiness, dizziness, confusion, anxiety, agitation, to coma.
Ataxia is the most common sign of toxicity, occuring in 90% of patients. Respiratory depression is not a common side effect but can occur with combinations of other CNS depressants.
Will activated charcoal work for iron table overdose?
No
Activated charcoal does not bind to iron.
Treatment include IV deferoxamine for patients with systemic toxicity or other risk factors. Hemodialysis is additionally not effective at removing iron from the blood.
Parasthesias (mouth, face and limbs), ataxia, weakness, and an odd floating sensation are associated with what type of ingestion?
What is the treatment?
Paralytic shellfish poisoning.
Treatment is supportive.
Usually bivalve molusks which accumulate saxitoxin that is generated from microscopic algae. Symptoms can develop in minutes to hours from ingestion. Treatment can include respiratory support.
Dystonia, parkinsonism, seizures, VT and pinpoint pupils can be seen with an overdose of what commonly used medications?
Phenothiazines:
Compazine (prochlorperazine)
Phenergan (promethazine)
Thorazine (chlorpromazine)
This class of medications work to inhibit dopamine receptors centrally, as well as peripherally on the vagus nerve.
Profound weakness (especially in patients with myasthenia gravis) is a sign of toxicity of which drug group?
Aminoglycosides
Although less common, neuromuscular blockade can occur due to inhibited acetylcholine release at the synaptic cleft by decreasing the amount of calcium released through calcium channels.
Other common effects in toxicity:
Ototoxicity to vesitublar and cochlear cells
Nephrotoxicity causing proximal tubular damage and ATN
At what post-ingestion time will you know if the amount of acetaminophen ingested was toxic? What is the treatment threshold at this time?
Four hours, acetaminophen level > 150 mcg/dl
Utilize the rumack-matthew normogram to determine the level of toxicity. Treatment is n-acetyl cysteine (NAC). Tylenol toxicity has multiple stages with worsening liver injury, sometimes requiring liver transplant.
A patient presents with vomiting, is hypotensive, bradycardic, and hyperkalemic most likely ingested what drug? What is the treatment?
Digoxin, treatment is with digoxin specific antibodies.
Watch out for hyperkalemia, once treated with antibodies, K will rapidly correct. Calcium in setting of hyperkalemia has theoretical risk of Stone Heart. EKG on Digoxin will have characteristic “scooped out” ST-depressions
A patient presents with vomiting, is hypotensive, bradycardic, and hyperglycemic most likely ingested what drug? What is the treatment?
Calcium channel blocker.
initial treatment is with calcium salt, which may improve HR and BP. High dose insulin can also be used 1-10 u/kg/hr with glucose.
If refractory to calcium and insulin, treatment can include vasopressors or pacing if hypotensive and have severe bradycardia with HR <30
A patient is pulled from a house fire with significant lactate >10. In addition to treatment for possible CO poisoning, what else must be considered? What is the treatment? What must be avoided?
Cyanide toxicity from combustion of household fibers.
Treatment for this is hydroxycobalamin. Cyanide is a byproduct of nitrogen containing polymers. Blocking of cytochrome oxidase in mitochondria causes break-down of the electron transport chain.
Avoid sodium nitrites in older cyanide kits in patients with concern for concomitant CO poisoning.
Which drugs can present with an anticholinergic toxidrome, wide QRS, hypotension? What is the treatment?
Tricyclic antidepressants (TCA).
Treatment includes: sodium bicarbonate, airway protection, and pressors. QRS > 100 ms is an indication for sodium bicarb, EKG will have pathognomonic terminal R wave in aVR
What drug presents with refractor status epilepticus with a high anion gap acidosis? What is the treatment?
Isoniazid
Treatment is pyridoxine and aggressive supportive measures. Hemodialysis can be effective for removing lactic acid and isoniazid if required.
Clinical presentation: an avid hiker and forager presents with abdominal pain, vomiting and diarrhea 6 hours after finishing a hike. Two days later the patient is in fulminant liver failure. What kind of mushroom did the patient eat?
Amanita phalloides (death cap mushroom)
Amanita mushrooms are known to cause a delayed onset hepatotoxicity. The majority of deaths caused by mushroom ingestions can be from this species. Silibinin and NAC have been shown to have mortality benefits but prepare for possible liver transplantation.
A patient comes in and says they were cleaning out their attic and were bit by a spider that they saw was black and had a red hourglass on it. What type of spider bit them and what is the treatment?
Black widow
Care is supportive, including ice packs and NSAIDs. Local wound care is the mainstay of treatment. If the patient is showing signs of systemic symptoms, antivenom can be used
A patient suddenly develops a metallic taste in their mouth while you are finishing suturing a patient with numerous lacerations. What is the recommended maximum dose of lidocaine?
Lidocaine without epi: 5 mg/kg
With epi: 7mg/kg
Treatment is aggressive supportive care with mechanical ventilation and intralipid therapy.
Toxicity generally presents within minutes of injection. A common source of toxicity is injection intravascularly, which can cause toxicity at less than the maximum recommended dose.
A toddler got into their grandmother’s medicine cabinet and took one of her medications but they do not know which one. Which common classes of medicine should you be particularly aware of?
Cardiac drugs: amlodipine, nifedipine, verapamil, diltiazem, clonidine
Sulfonylureas: Gliclazide
Antidepressants: amitryptyline, diazepine, temazepam
Parkinson’s drugs: Selegiline
The average toddler weighs 10-15 kg, these drugs have very low weight based doses and are known as one pill killers
