Toxidromes Part I

Question 1

Describe the mechanism of action of cocaine and the signs and symptoms associated with its administration.

Answer 1

It is a sympathomimetic leading to tachycardia, increased alertness, hypertension, etc.

Question 2

What is the least reliable route of absorption of cocaine?

Answer 2

PO –> oral ingestion of cocaine is only lethal in very large amounts

Question 3

What is the most reliable route of absorption of cocaine?

Answer 3

Smoking cocaine easily crosses the alveoli and the blood-brain barrier

Question 4

What are some common emergent sequelae of cocaine toxicity?

Answer 4

Stroke, including intracerebral or subarachnoid hemorrhage
Decreased seizure threshold
Chest pain associated with MI
Rhabdomyolysis
Anxiety and psychosis

Question 5

What medications and interventions (7) are used to manage complications associated with cocaine toxicity?

Answer 5

Benzos - anxiety and to stop seizures
Phenytoin - to prevent seizures
Haloperidol - anxiety
Ca Channel Blockers - HTN
Bicarb - rhabdomyolysis (alkalinizes the urine)
IV fluids - rhabdomyolysis
CT scan and supportive care - HA or stroke

Question 6

Why are beta blockers avoided in cocaine toxicity?

Answer 6

Resultant unopposed alpha-1 stimulation may result in further HTN

Question 7

List 2 reasons CO toxicity is on the decline in recent years.

Answer 7

Increased use of CO detectors

Decreased CO emissions from automobiles

Question 8

What is the mechanism of action that causes CO toxicity?

Answer 8

CO binds to Hgb with 250x more affinity than O2. The resultant anaerobic metabolism leads to metabolic acidosis which causes the body’s enzymes (which are proteins) to denature

Question 9

Where is someone likely to be exposed to CO?

Answer 9

In a fire - especially in closed spaces

Question 10

How is a diagnosis of CO toxicity made and what drives treatment?

Answer 10

Dx based on serum carboxyhemoglobin. Often times the patient cannot wait for this lab to return for treatment to start. So treatment is driven by presenting S/S.

Question 11

What is the treatment for CO toxicity?

Answer 11

High flow O2 for all patients.

Hyperbaric oxygen for severe cases with decreased consciousness.

Question 12

T/F: TCAs account for a small amount of overdoses and deaths.

Answer 12

False: TCAs are involved in 12% of intentional ODs and 36% of deaths.

Question 13

What three things are a major part of the clinical presentation of a TCA overdose?

Answer 13

Tonic-clonic seizures
Cardiac arrhythmias
Anticholinergic affects (C-DUST)

Question 14

How does a potential TCA overdose affect administration of the classic drug cocktail for an unresponsive patient?

Answer 14

Flumazenil (a benzo antagonist) is part of the drug cocktail. If the patient OD’d on TCAs and flumazenil is administered, they are more likely to have a seizure that is difficult to stop.

Question 15

What ECG finding is most consistent with TCA toxicity?

Answer 15

Wide QRS

• QRS of 0.10 - 0.15 = increased risk of seizure
• QRS > 0.16 = increased risk of seizure and arrhythmia
• QRS < 0.10 does not rule out toxicity

Question 16

What is the treatment of TCA toxicity and why is it effective?

Answer 16

Sodium bicarbonate for 2 reasons.

• increases plasma protein binding of the drug
• stabilization of fast Na channels

Question 17

What two drugs that are not TCAs but when in toxicity are treated the same as TCA toxicity?

Answer 17

Cyclobenzaprine and Carbamazepine

Question 18

What is the classic triad of S/S associated with opioid toxicity?

Answer 18

Miosis (pinpoint pupils)
Decreased level of consciousness
Respiratory depression

Question 19

What is the antidote for opioid toxicity used to reverse respiratory depression?

Answer 19

Naloxone –> 2mg IV

Question 20

If IV access is unavailable, what other route of administration is the antidote for opioid toxicity given?

Answer 20

ET Tube (intubation)

Question 21

For what opioids are a large amount of naloxone required for reversal?

Answer 21

Pentazocine, codeine, methadone

Question 22

What is important in the management of opioid toxicity after the initial dose of naloxone is given?

Answer 22

All opioids have a longer half life than naloxone. Continuous naloxone infusion is administered at an hourly rate at 2/3 the amount in mg that was needed to reverse the respiratory depression.

Question 23

Differentiate naltrexone from methylnaltrexone from naloxone.

Answer 23

Naltrexone is an opiod antagonist with a longer half life than naloxone. It can be used to ween SUD patients off of narcotics. But naltrexone cannot be used in toxicity.
Methylnaltrexone is used to counter opioid induced constipation