Clinical Toxicology Flashcards
It is often impossible to establish with certainty the identity of the poison and the size of the dose. Why is this not usually important?
Because only a few poisons (such as opioids,
paracetamol, and iron) have specific antidotes. Few patients require active removal of the poison.
In most patients, treatment is directed at managing symptoms as they arise.
Management of suspected poisoning?
Resuscitation + Stabilization Evaluation Identify what you can Symptomatic care + monitoring Prevention of deterioration Treat symptoms Specific antidotes
Resuscitation & Stabilization - how do you assess/manage a suspected poisoning patient?
Airway – Evaluation of patency ± correction ± Oxygen
Breathing – RR, air entry, SpO2…
Circulation – central pulse, central cap refill, brachial BP, ECG… ± iv fluids
Disability – AVPU scale; pupils; capillary blood glucose
Everything else - Temperature
What is it important to ask about in the history of a suspected poisoning patient?
What drug(s) were taken? What dose/number of tablets were taken? When where they taken? Were they taken all at once or staggered? Are there empty packets/bottles of drugs? Witnesses? What co-morbidities are present? What are the concomitant drugs/toxins? Is there evidence of high suicidal risk (notes etc.)? Allergies? Last meal? Previous poisonings? Current symptoms?
Examination of a suspected poisoning patient.
What are the cardio-respiratory observations?
Is there evidence of specific organ failure?
What is the temperature?
Is the patient sweating?
What is the level of consciousness?
What are the pupil size/pupillary responses to light?
Are there signs of CNS involvement?
Agitation; neck stiffness; clonus
How should a suspected poisoning be investigated?
Can we test for the specific poison of interest?
What tests are required for monitoring of likely
affected organs?
How can absorption be prevented?
Activated charcoal within 1h ingestion - 50mg orally in conscious patient, or 50mg by NG tube if obtunded and protect airway
Gastric lavage
What substances don’t bind to charcoal?
Ethylene glycol, Iron, Lithium, Methanol, Strong acids and alkalis
What substances is gastric lavage indicated for?
iron, lithium
What drugs is enhanced elimination indicated for?
carbamezepine, dapsone, phenobarbital, quinine, theophylline
What is the dosage for enhanced elimination (using charcoal)?
Multi-dose activated charcoal
50g every 4hours
Other methods of enhanced elimination? (2)
Haemdialysis for drugs with low volume of distribution e.g. aspirin, toxic alcohols, lithium, valproate
Urine alkalinization for aspirin (TCAs)
Beta blocker overdose - symptoms?
Presents with hypotension and bradycardia
Associated features include hypothermia and hypoglycaemia
Beta blocker overdose treatment.
Atropine 0.5-2mg ivi for bradycardia
Glucagon 5-10mg iv bolus + 50-150 mcg/kg/h titrated to clinical response can cause nausea and vomiting, hyperglycaemia
High-dose insulin (1u/kg bolus + 0.5-2u/kg/h) + 10%
dextrose
Temporary wire pacemaker/external pacing
TCA overdose symptoms?
- anti-muscarinic effects (confusion, agitation, dry skin, hyperthermia, thirst, dry mouth, mydriasis, tachycardia, urinary retention, ileus)
- myocardial sodium channel blockade (broad QRS, any arrthythmia from asystole to VF)
- alpha-1 adrenergic antagonism
- CNS effects (confusion, delirium, myoclonus, seizures)
