Toxicology Flashcards
A 34 year old male presents in acute respiratory failure. The treating paramedics noted pin point pupils en-route and administered 800mcg naloxone IV. On arrival and initial examination you note the lungs sound wet and there are ++ upper airway secretions.
What drugs do you think are responsible?
What antidote would you consider?
Organophosphorous agents.
Treat with atropine starting at 1.2mg. Further doses are given every 2-3 mins, doubling the dose each time until drying of the secretions is achieved.
Your very dischevelled looking patient presents very altered, breathing very slow and shallow, you see significant metabolic acidosis on initial ABG/VBG. What should you think of?
Ethylene glycol, methanol - non-beverage alcohol
What toxin exposure is made worse by the application of oxygen?
(probably out of my scope)
Paraquat (herbicide) - causes oxygen free radical mediated cellular injury to the type II pneumoncytes
Where possible avoid supplemental oxygen, if this occurs titrate supplemental oxygen to maintain sats at 90% or a PaO2 60 mmHg
A patient presents in VFib, defibrillation not working. The wife tells you he spilled a chemical on his hands earlier, thinks from an old fridge (or maybe he smashed a box of flourescent lights)…
What is the chemical?
What electrolyte imbalance does it cause?
So what should you give?
Flourine in solution is hydrofluoric acid.
Extensive cutaneous exposure causes hypocalcemia.
Give boluses of calcium gluconate 2g IV q2mins alongside defibrillation may restore a perfusing rhythm.
A patient presents after an unknown ingestion (or maybe sketchy recreational drug use) with a wide complex tachycardia in arrest (VT). Again defibrillation is not working.
There are multiple drugs responsible but what “antidotes” would you use and what antiarrhythmic sometimes used in resuscitation would you not use?
- boluses of sodium bicarbonate
- do NOT use amioderone
- consider urgent intubation and hyperventilation
Many drugs (rx ad recr) have sodium channel blocking properties and in overdose this precipitates widening of the QRS until VT occurs.
NaHCO3 gives a sodium load as well as creates an alkalotic state which helps reduce the binding of the drug to various sites including the myocardium.
Amiodarone is contraindicated as it also has sodium channel blocking effects (also procainamide, + others)
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A couple of lads come off the street having injected something, they complain of tachycardia and the screen shows a HR of 160 and a BP of 200/140. You suspect amphetamines or cocaine. You know that beta blockers are contraindicated but what drug could you use to lower both the HR and BP?
IV benzodiazepines
e.g. diazepam 5mg IV and titrate every 5 mins potentially with increasing doses to reach a HR close to 100-110.
Usually this only results in minor sedation and does not require intubation as a result of your benzodiazepine use. BP will also decrease due to benzodiazepine receptors in the vascular system.
What toxins that cause bradycardia and hypotension would you treat with high-dose insulin therapy?
BB and CCB
What drug can cause ANY arrhythmia?
Clue: It is typically use in the elderly for AF and can present with very non-specific signs such as nausea. What is the antidote?
digoxin - AV node blocker
digibind - digoxin-specific antibodies
Apart from benzodiazepines (and lots of them) +/- barbiturates to control the toxic seizure, there are two drugs that require a different therapy. What are those drugs and what are their corresponding treatments?
Isoniazid and this requires pyridoxine 1g per gram of isoniazid ingested, up to 5g
Theophylline – urgent haemodialysis
Cyanide – hydroxocobalamin, thiosulfate or dicobalt edetate.
You have a two year old who is profoundly hypoglycaemic after swallowing a couple of pills, despite multiple boluses of dextrose. You know the hypoglycaemia cannot be secondary to insulin or an alcohol.
What is the likely agent and what antidote do you need to turn off the hyperinsulinaemic state?
sulphonyureas - insulin secretagogues
octreotide bolus then infusion - administration will reduce the requirement of dextrose supplementation as it suppresses the release of endogenous insulin from the pancreatic cells
“antidote” in insulin or sulphonylurea overdose
dextrose
if persistent, octreotide
Antidote for arrhythmias with hydrofluoric acid; temporizing measure in calcium channel blockers toxicity
calcium gluconate
Antidote for severe TCA overdose or sodium channel blockade?
sodium bicarbonate
Very helpful for organophosphate poisoning
atropine for secretions
When is gastric lavage indicated?
Recent (<1 hour), large, high toxic ingestion
NAC administration for tylenol overdose in what timeframe?
6-8 hours
Toxic tylenol dose for adult?
7.5 g (15 extra strength pills)
The antidote for benzodiazepine overdose
Should you use it? Why?
Flumazenil
