Toxicology

Question 1

Typical metabolic abnormality or laboratory finding to expect in Beta-blocker toxicity or overdose

Answer 1

❌Catecholamine induced hepatic glucose production and glycogen breakdown▶Hypoglycemia

Question 2

Which arterial blood gas result would you find in a carbon monoxide poisoning?

Answer 2

• Lactic acidosis→↓ bicarbonate, ↓pH (tissue hypoxia)

- ↑ Carboxyhemoglobin levels

Question 3

Which finding do you expect to find in cell blood count in a patient with chronic carbon monoxide poisoning?

Answer 3

Kidney responds to tissue hypoxia→↑EPO→Secondary polycythemia

Question 4

Treatment for anticholinergic toxicity

Answer 4

Physostigmine►cholinesterase inhibitor

Question 5

Most common sources of exposure for cyanide intoxication

Answer 5

• Dermal: partial immersion in liquid cyanide or cyanide solutions or contact with molten cyanide salts
• Inhalational: Hydrogen cyanide, product of combustion from nitrogen-containing synthetic polymers (foam, cotton, paint, silk, etc)►Faster onset of symptoms
• Intestinal: ingestion of amygdalin (cyanogenic glucoside in apricot seeds), cyanide directly

Question 6

Which empiric treatment should be done in unconscious victims of smoke inhalation?

Answer 6

Cyanide toxicity→Hydroxicobalamin►forms Cyanocobalamin; Sodium thiosulfate or Nitrites►induce methemoglobinemia

*Prevent cardiorespiratory arrest and permanent neurologic disability

Question 7

Two major products of combustion in closed spaces

Answer 7

Hydrogen cyanide (HCN) and Carbon monoxide (CO)

Question 8

Best initial management of altered mental status of unclear etiology (suspecting intoxication)

Answer 8

• Opiate antagonist→Naloxone (give immediately, opiate overdose is fatal)
• Dextrose

Question 9

Keys on clinical presentation to diagnose aspirin overdose

Answer 9

• Tinnitus and hyperventilation
• Respiratory alcalosis
• Metabolic acidosis with ↑ Lactate

Question 10

Best initial test when suspect tricyclic antidepressant toxicity and why?

Answer 10

EKG➡look for cardiac toxicity

• Widening of the QRS complex➡⬆risk ventricular arrhythmia
• Prolongs QT→Torsade de Pointes

Question 11

Severe symptoms of carbon monoxide poisoning and most appropriate treatment

Answer 11

• Severe CO intoxication:
• Cerebral hypoxia: Drowsiness, confusion, seizures, syncope, coma
• Myocardial injury: Ventricular arrhythmia, myocardial ischemia, pulmonary edema (cardiac dysfunction or CO-induced alveolar damage)
• Lactic metabolic acidosis
• Treatment: Hyperbaric oxygen

*Not severe, treat with 100% Oxygen

Question 12

Best initial and most effective therapy for Methemoglobinemia

Answer 12

• Best initial: 100% Oxygen

- Most Effective: Methylene blue (↓ half-life)

Question 13

Treatment for Lead poisoning

Answer 13

• Oral: Succimer

- Parenteral: Ethylenediaminetetraacetic acid (EDTA) and dimercaprol (BAL)

Question 14

Most accurate test and best initial test for Lead poisoning

Answer 14

• Most accurate: Lead level

- Best initial: Level of free erythrocyte protoporphyrin

Question 15

Management for tricyclic antidepressant cardiac toxicity

Answer 15

Sodium bicarbonate for QRS widening (>100 msec) or ventricular arrhythmias

Question 16

Most reliable sign of opioid intoxication. Which other clues you may find?

Answer 16

⬇Respiratory rate

• Bradycardia
• Acute change in mental status
• Miosis
• Hypotension
• Hypothermia
• Hypoactive bowel sounds

“BAM3H”

Question 17

How do you suspect inhalant abuse acute intoxication?

Answer 17

• Brief transient euphoria and loss consciousness
• Highly lipid soluble➡immediate effects (typically last 15-45 minutes)
• Dermatitis due chemical exposure around the mouth or nostrils▶”glue sniffer’s rash”
• Chronic abuse of nitrous oxide➡vitamin B12 deficiency▶polyneuropathy

Question 18

Remarkable and helpful laboratory finding to diagnose Ecstasy intoxication

Answer 18

Hyponatremia

Question 19

Which etiology suggests a high anion gap metabolic acidosis with an osmolal gap?

Answer 19

• Poisoning with:
• Acute ethanol (most common)
• Acute Methanol
• Acute Ethylene glycol

Question 20

Classical finding in acute ethylene glycol poisoning

Answer 20

• Rectangular, enveloped-shaped calcium oxalate crystals on urinalysis
• Most commonly antifreeze ingestion

Question 21

Most common complication of acute ethylene glycol poisoning

Answer 21

Acute renal failure

Question 22

Signs and symptoms of tricyclic antidepressant overdose or toxicity

Answer 22

• Hyperthermia
• Anticholinergic effects➡skin flushing, intestinal ileus, mydriasis, dry mouth, urinary retention
• Seizures
• Cardiac toxicity:
• ❌cardiac fast Na+ channels➡QRS prolongation▶⬆risk ventricular arrhythmia
• Hypotension➡can be refractory to tx➡major cause of mortality in TCA overdose

Question 23

Treatment for cardiac toxicity by TCA overdose

Answer 23

Sodium bicarbonate➡improves systolic blood pressure, narrows QRS, ⬇incidence ventricular arrhythmia

*Alkalinization➡neutral form TCA is less available to bind Na channels