Toxicology 2

Question 1

Name 5 drugs that can cause serotonin syndrome?

Answer 1

1. TCA’s
2. SSRI
3. Opiates and meperidine
4. MAOI
5. Anti-emetics (zofran, metaclopramide)
6. Drugs of abuse (MDMA, ectasy, LSD)
7. Anti-migrane meds (sumatriptan)
8. Anti-biotics (Linizolid)
9. OTC cough medications (Dextromethorophan)
10. Weight reduction agents
11. Lithium

Question 2

What is the difference between fever and hyperthermia?

Answer 2

Hyperthermia: Elevated body temperature due to failed thermoregulation. Can be extrinsic (heat stroke) or intrinsic (body making more heat than it can dissipate - malignant hyperthermia, NMS, serotonin syn, cocaine, amphetamines - due to muscle activity).

• Too much heat production or not enough dissipation
• There is no increase in body’s set point

Fever: there is an increase in the hypothalamic body’s set point. this leads to inc m. contraction causing feeling of cold. THis results in greater heat production and efforts to conserve heat. When the set point temp returns to normal a person feels hot, becomes flushed and may begin to sweat.

Question 3

What are signs and symptoms present in serotonin syndrome?

Answer 3

1. Autonomic instability
   - Hyperthermia
   - Tachycardia
   - Hypertension - can decompensate to shock..
   - Diaphoresis
   - Mydriasis
   - Shivering
   - Diarrhea
2. Neurologic
   - Mental status change
   - Ocular horizontal clonus (?specific)
   - Clonus (LE >UE)
   - Hyper-reflexia
   - Tremor
   - Incr Tone (LE>UE)
   - Muscle rigidity
   - Seizures
3. Systemic
   - Rhabdomysis
   - Transaminitis
   - AKI
   - DIC

Life threatening state: hyperthermia, hypertonicity

Question 4

What is the most important physical exam finding when diagnosing serotonin syndrome?

Answer 4

Clonus

• Inducible
• Spontaneous
• Ocular

Question 5

What other diagnoses should you also think of when thinking the patient has serotonin syndrome?

Answer 5

1. NMS
2. Anti-cholinergic syndrome (AMS, hot, dry, mydraiasis, constipation, urinary retention)
3. Malignant hyperthermia (incr CO2, incr. tone, hyperthermia, metabolic acidosis, rigor mortis like rigidity)

Can be distinguished by history and physical

Question 6

What is Neuroleptic malignant syndrome?

Answer 6

Is an idiopathic reaction to Dopamine antagonists

• Slow onset (days)
• Bradykinesia
• Akinesia
• Lead pipe m. rigidity
• Hyperthermia
• AMS
• autonomic instability

Question 7

What is the management for Serotonin syndrome?

Answer 7

1. Supportive, IVF, intubate, paralyze.
2. Benzodiazapines: blunts the hyperadrenergic component of syndrome
3. Cyproheptadine (efficacy has not been rigorously established)
   - is a 5-HT2A antagonist
4. Chlorpromazine (dopamine antagonist) - but can make NMS worse.

Propanolol (5ht1a antagonist), bromocriptine (dopamine agonist) and dantrolene (post synaptic m. relaxant) are not recommended.

Question 8

What is the ddx of hypotension and bradycardia?

Answer 8

1. Betablockers
2. Calcium channel blockers
3. Digoxin
4. Clonidine
5. Cholinergic agents (will have ‘sludge’ symptoms also tho)
6. Hypothyroid (Myxedema coma)
7. Shock - cardiogenic, Neurogenic
8. Acute MI (inferior)
9. Sepsis
10. ENdocrine disorder
11. Sedative hypnotic drugs
12. Hypothermia
13. Hyperkalemia
14. Neurogenic shock
15. Na Channel blockeres
16. Incr ICP
17. Sick sinus syndrome
18. Opiods!

Question 9

What is the classic visual change associated with digoxin toxicity?

Answer 9

Xanthopisa (yellow halos)

Question 10

What are some common ekg findings of digoxin toxicity?

Answer 10

1. paroxysmal atrial tachycardia
2. AVN block
3. Bidirectional ventricular tach (pathnomonic)
4. Any dysrhythmia really.