Toxicology

Question 1

What are the two medications used in organophosphate poisonings?

Answer 1

atropine - competitive inhibitor of acetylcholine at muscarinic receptors.

pralidoxime - 2-PAM forms a complex with the bound acetylcholinesterase enzyme to cause the release of the organophosphate from the enzyme. This results in regeneration of its ability to metabolize acetylcholine

Question 2

What is the goal of treatment with atropine in an organophosphate poisoning?

Answer 2

The goal of treatment with atropine is to titrate to the drying of bronchial secretions.

Question 3

Which ingestion is classically associated with visual disturbances described as “snowstorm appearance.”

Answer 3

Methanol

Question 4

What is the treatment for methanol/ethanol ingestion? What is the mechanism of action?

Answer 4

Treatment is based on metabolic blockage of the parent compound to its more toxic metabolites as well as the removal of the toxic metabolites.

Inhibiting alcohol dehydrogenase is accomplished by either fomepizole or ethanol

Question 5

What adjunctive medication can be used to increase metabolism of methanol?

Answer 5

folate or folic acid - it increases metabolism of formate into CO2 and water

Question 6

What are indications for dialysis in a toxic alcohol ingestion?

Answer 6

1 - refractory metabolic acidosis
2 - visual disturbances
3 - renal abnormalities
4 - deteriorating vital signs despite aggressive therapies
5 - refractory electrolyte abnormalities
6 - if methanol/ethylene glycol levels >50 mg/dL

Question 7

Which laboratory value should be carefully monitored in an ethylene glycol ingestion?

Answer 7

Calcium levels should be closely monitored as calcium oxalate can precipitate causing severe hypocalcemia.

Question 8

What adjunctive medications can be used to increase metabolism of ethylene glycol?

Answer 8

Supplementation of pyridoxine and thiamine can be used to aid in removal of toxic metabolites

Question 9

What is the toxic metabolite of methanol?

Answer 9

formic acid

Question 10

What is the toxic metabolite of ethylene glycol?

Answer 10

oxalic acid

Question 11

What is the dosing for atropin in organophosphate poisoning?

Answer 11

1–3 mg intravenously every five minutes until drying of airway secretions

If venous access cannot be obtained immediately, 2–6 mg may be given intramuscularly.

Question 12

What is the IV regimen for IV N-aceytlcysteine?

Answer 12

The IV regimen is 150 mg/kg loading dose over 15 minutes, followed by 50 mg/kg over the next four hours, 100 mg/kg over the following 16 hours, and finally 300 mg/kg every hour after 21 hours until the acetaminophen level and hepatic function tests have normalized.

Question 13

What is the mechanism of action for N-acetylcysteine?

Answer 13

NAC works by regenerating the sulfhydryl donor glutathione.

Question 14

What two laboratory values assess hepatic function?

Answer 14

Prothrombin time and serum albumin

Question 15

What is the classic ECG finding in TCA overdoses?

Answer 15

The classic ECG finding in TCA overdose is a terminal R wave seen in lead aVR.

Question 16

How long should a patient with a monoamine oxidase inhibitor (MAOI) overdose be monitored?

Answer 16

24 hours

Question 17

When do you treat widened QRS with sodium bicarbonate?

Answer 17

> 100 ms with symptoms or >120 ms

Question 18

What is the difference between alkali and acidic ingestion?

Answer 18

Alkali cause liquefaction necrosis, which results in extremely rapid, deep penetration into tissues. Alkali commonly cause severe esophageal injuries due to this rapid penetration and to the partial neutralization of the substance in the stomach.

Acids, which cause coagulative necrosis, thereby creating an eschar and preventing deeper spread into tissues. As a result, acids are more likely to injure the stomach and spare the esophagus

Question 19

What is the Emergency Department management for caustic ingestions?

Answer 19

Emergency department management includes aggressive airway management for any signs of airway compromise and close monitoring for signs of esophageal perforation.

Question 20

What is the disposition for patients with a caustic ingestion?

Answer 20

All patients with caustic ingestions should be admitted for an endoscopy within 24 hours.

Question 21

What laboratory abnormalities are characteristic of hydrofluoric acid burns?

Answer 21

Hypocalcemia and hypomagnesemia is characteristic of hydrofluoric acid burns.

Question 22

What ECG finding is indicative of digoxin use?

Answer 22

scooped ST segments (Salvador Dali mustache) and PR prolongation.

Question 23

What are the indications for Digibind in an acute overdose?

Answer 23

an elevated digoxin level of 10-15 nanograms/ml, a serum potassium >5.0 mEq/dl or in the presence of severe conduction disturbances (any ventricular dysrhythmia, bradydysrhythmias unresponsive to atropine).

Question 24

What medication is contraindicated in digoxin overdose?

Answer 24

Calcium administration is contraindicated in digoxin overdose as it may lead to “stone heart” or cardiac standstill by acutely increasing intracellular calcium concentrations.

Question 25

Is hemodialysis indicated in digoxin overdose?

Answer 25

No, hemodialysis is ineffective as the volume of distribution of the drug is large.

Question 26

Is tranvenous pacing indicated in digoxin overdose?

Answer 26

No, transvenous pacing has been associated with an increased risk fatal ventricular tachydysrhythmias secondary to digoxin causing an irritable myocardium.

Question 27

What classic physical exam finding accompanies lead poisoning?

Answer 27

Burton lines - blue lines on the gingiva adjacent to the teeth.

Question 28

Which opiate is associated with prolonged QTc intervals and risk for torsades de pointes.

Answer 28

Methadone has been associated with a prolonged QTc interval and risk of torsades de pointes.

Question 29

What medications do you use to treat hypertension caused by cocaine toxicity?

Answer 29

Benzodiazepines and phentolamine

Question 30

What outcome has been borne out in the literature regarding hyperbaric oxygen for carbon monoxide poisoning?

Answer 30

Hyperbaric oxygen therapy has been shown to decrease the risk for developing delayed neurologic sequelae in patients with carbon monoxide (CO) poisoning.

Question 31

What other toxin is commonly a co-inhalant in a fire with carbon monoxide?

Answer 31

Cyanide