Poisoning and Toxicology
34 year old man presents to the hospital after
being found in his apartment.
According to NetCare, he has no significant past
medical history except for multiple emergency
room visits for coma from alcohol overdoses.
He does not respond to painful stimuli and his
breathing is shallow with O2 sats 89% but his
blood pressure is 112/47 and heart rate is 85.
You suspect that the patient has an
overdose. What further information should
you seek?
– EMS: Empty cheap liquor bottles found at the
scene. No suicide note nor any prescription
medications.
– Friend listed as contact: No known
prescribed medications. Lots of problem with
alcohol and recently was cut off EI and has
run out of money.
When examining the patient, what toxidromes
and characteristics should you look for?
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Sympathomimetics
Anticholinergic
Hallucinogenics
Opioid
Sedative-hypnotic
Cholinergic
Serotonin
Tricyclic antidepressant
What investigations would you order?
Describe the initial approach to the
management of the poisoned patient.
– Airway
– Breathing
– Circulation
– Decontamination
What antidotes are available and what role
do they have in poisonings?
On ABG, the patient is found to have an anion
gap of 23.
What is the differential for poisonings with an
anion gap?
– Consider:
Methanol, ethanol, ethylene glycol
INH, salicylates, metformin
CO,CN, H2S, methemoglobin (cellular asphyxiants)
Sympathomimetics
How would you calculate the osmolar gap?
The osmolar gap is 39. The ethanol level
is 5 mmol/L. What is the differential for an
elevated osmolar gap?
– Consider:
Ethanol, ethylene glycol, methanol, isopropyl
alcohol
Mannitol
While awaiting confirmatory tests, you
decide to initiate therapy. What treatments
are available?
56 year old man with a past history of CAD
presents with SOB and ringing in the ears.
His initial ABG demonstrates a pH 7.45,
PCO2 20, PO2 110, HCO3 20 and lactate
5.
In the absence of any further history, what
is the most likely ingestant?
What is the mechanism of action of
salicylate toxicity?
Describe the clinical features (symptoms,
signs and acid/base abnormalities) of
salicylate toxicity?
Discuss the management of salicylate
intoxication?
What is the role for alkalinization?
What is the role of hemodialysis?
23 year old woman with a past medical
history of depression presents to the
hospital after reportedly taking 50 extrastrength Tylenol 3 hours ago.
On examination, she is hemodynamically
stable with no physical findings and no lab
abnormalities.
What is your initial approach and
management of this patient?
How does acetaminophen cause
hepatoxicity and how does Nacetlycysteine prevent it?
Suppose the patient presented 72 hours
after ingestion. Her ALT is 1250, tylenol
level 0, pH 7.23 and INR 3.0.
How would you alter your management?
At what point would you consider
transplant?
24 year old boyfriend of the previous patient
presents to hospital with acute psychosis.
Soon after arrival, he develops generalized
seizures lasting 15 seconds.
On examination, he is febrile, blood pressure
87/32, heart rate of 143, O2 sats 91% on 5
L/min.
Between seizures he is flushed, generally stiff
with upgoing toes and clonus. His pupils are
dilated, and his abdomen is distended.
Head CT is normal as is CXR and ECG
demonstrates only sinus tachycardia.
What toxidrome does this presentation
most resemble?
EMS confirms that several empty bottles
of Elavil were found at the scene as well
as a suicide note. The patient is quite
distraught by his girlfriend’s recent
hospitalization.
What are the pharmacological effects of tricyclic
antidepressants?
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Presynaptic neurotransmitter reuptake
Cardiac sodium channels
Muscarinic acetylcholine receptors
Peripheral alpha-1 adrenergic receptors
Histamine receptors
GABA-A receptors
Describe the clinical features of TCA overdose;
especially the cardiac, CNS and peripheral
effects.
How would you resuscitate this patient?
What role does NaHCO3 have in the
management of TCA poisoning and how does it
work?
If the patient developed a wide complex
tachycardia, what antiarrhymics could be used?
How would you treat this patient’s seizures?
What issues can occur when decontaminating?
68 year old man with a history of heart
failure recently started on Paxil for
depression presents with fatigue,
abdominal pain, confusion, and vomiting.
His vital signs are 112/83, pulse 35,
respiratory rate 20, and O2 sats 95%.
His initial ECG demonstrates junctional
rhythm.
His ABG is normal except his K is 5.5.
You suspect drug toxicity after ruling out other
causes. What medications are on the differential
diagnosis?
The digoxin level is 4.6 nmol/L.
What is the mechanism of action of digoxin and
why is it toxic?
How would you treat this patient?
Should you treat the hyperkalemia?
Would a potassium level of 3.4 mmol/L be
reassuring?
Questions??