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Acute Care > Toxicology > Flashcards

Toxicology Flashcards

1
Q

What bloods would you check in someone who has overdosed on paracetamol

A

Paracetamol level
LFT
Clotting - INR

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2
Q

What is the antidote to paracetamol overdose

A

N-acetylcysteine

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3
Q

You should take a paracetamol level immediately after overdose - true or false

A

False

4 hours is the cut off for a blood test, will not get an accurate level until this point as takes a while to absorb

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4
Q

How does N-acetylcysteine work

A

Glutathione stores in the liver are used to break down paracetamol safely by conjugating with the toxic metabolite NAPQI
If you exceed your stores, such as in OD, the NAPQI builds up which causes the liver damage.
The NAC acts as a substrate to glutathione so prevents this damage

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5
Q

What should you do if someone develops a rash on N-acetylcysteine

A

Some people can be allergic to NAC
They develop an anaphylactoid reaction in the form of urticarial rash NOT true allergy/anaphylaxis
Stop the infusion, give antihistamine, wait for symptoms to settle then restart. It is not a true allergy so can continue

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6
Q

The dose of N-acetylcysteine is dependent on what

A

The patient’s weight

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7
Q

What are the criteria for discharge following a paracetamol overdose

A

INR must be <1.4
ALT okay
No signs of toxicity
Paracetamol level <10mg/L

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8
Q

How can you reverse a benzo overdose

A

Give flumazinil

Only licensed for iatrogenic overdose

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9
Q

Why can flumazinil not be used for deliberate or personal benzo overdose

A

If the person is a regular user they can be benzo dependent
By reversing you send them into withdrawal with seizures that you need benzos to treat!
These people are treated supportively

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10
Q

What is a toxidrome

A

A collection of signs and symptoms signs caused by a toxin

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11
Q

What are the 5 major toxidromes

A 
Anticholinergic
Cholinergic 
Opiate 
Sympathomametic 
Sedative/hypnotic
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12
Q

Which drugs can cause the sympathomametic toxidrome

A 
Ecstasy 
Amphetamines and methamphetamines 
Cocaine 
LSD 
Theophylline 
Ritalin
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13
Q

Describe the basis of the sympathomametic toxidrome

A

Mimics the effects of the sympathetic nervous system

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14
Q

List common symptoms of the sympathomametic toxidrome

A 
Tachycardia - may cause arrhythmia
Increased RR
Raised BP 
Pyrexia - sweating
Dilated pupils
Tremor 
Hyperreflexia

Can be fatal via multi-organ failure or seizures

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15
Q

Which drugs can cause the opiate toxidrome

A 
Heroin
Morphine 
Codeine 
Fentanyl 
Tramadol
etc etc
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16
Q

List common symptoms of the opiate toxidrome

A 
Pin-point pupils 
Reduced RR, BP and HR
Reduced temperature 
Absent/decreased bowel sounds 
Reduced conscious level

Resp depression can cause death

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17
Q

Which drugs can cause the anticholinergic toxidrome

A 
Tricyclic antidepressants
Atropine 
Anti-psychotics 
Antihistamines 
Antiemetics

Belladonna - very rare!!

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18
Q

List common symptoms of the anticholinergic toxidrome

A 
Tachycardia 
- can cause arrhythmias, VT or VF
Pyrexia and flushed skin
Dry mouth
Urinary Retention 
Dilated pupils 
Absent bowel sounds
Confusion 
Ataxia
Dysarthria 
May have hallucinations/psychosis/seizures
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19
Q

Which drugs can cause the sedative/hypnotic toxidrome

A

Benzodiazepines
Zopiclone
Barbituates
Muscle relaxants

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20
Q

List common symptoms of the sedative/hypnotic toxidrome

A

Reduced GCS
Reduced RR and HR
Hypoxia - due to reduced resp effort
Reduced temperature

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21
Q

List common symptoms of the cholinergic toxidrome

A 
Pinpoint pupils 
Sweating 
Lacrimation 
Rhinorrhea 
Salivation 
Bradycardia 
Urination 
Vomiting and diarrhoea

Can lead to resp failure - oedema, spasm, failure
Also convulsions or coma

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22
Q

Which drugs can cause the cholinergic toxidrome

A 
Organic phosphate 
compounds - insecticide 
Sarin gas 
Pilocarpine 
Mushrooms
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23
Q

Which drugs can have their blood levels directly measured

A 
Paracetamol = 4 hours after ingestion 
Salicylates = at least 2 hours after ingestion if symptomatic and 4 hours if asymp.
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24
Q

How do you calculate the anion gap

A

(Na + K) - (Cl + HCO3)

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25
Q

When do you calculate the anion gap

A

If you need to determine the cause of a metabolic acidosis

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26
Q

List causes of a raised anion gap

A 
MUDPILES 
Methanol 
Uraemia 
Paraaldehyde 
Diabetic ketoacidosis 
Iron overdose 
Lactic acid 
Ethylene glycol 
Salicylate
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27
Q

How is activated charcoal used in overdose

A

Can be given within an hour of ingestion
Typically give 50g as a solution
It can reduce the absorption of the substance by binding to the toxin
Only works with certain drugs and is poorly tolerated

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28
Q

What is the most common cause of overdose in the West

A

Paracetamol

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29
Q

What is considered a safe dose of paracetamol

A

75mg/kg or less

75-100 is potentially toxic
and over this is likely toxic

30
Q

N-actylcysteine is a fast acting treatment - true or false

A

False

Takes up to 21 hours to deliver a dose

31
Q

What is the antidote to tricyclic antidepressant overdose

A

Sodium bicarbonate

32
Q

What is the antidote to beta blocker overdose

A

Glucagon - IV 5-10mg

33
Q

What is the antidote to opioid overdose

A

Naloxone
IM or IV
Titrate up to response - look for a rise in RR

34
Q

What is the antidote to ethylene glycol or methanol overdose

A

Ethanol
Fomepizole - inhibits dehydrogenase
Give sodium bicarb if acidotic

35
Q

What is the antidote to iron salts overdose

A

Desferrioxamine

36
Q

What is the antidote to organophosphate overdose

A

Atropine - to reduce bronchial secretions/spasm

Pralidoxime mesylate

37
Q

How can you enhance the elimination of a toxic substance

A

Enhance or augment renal function

  • urinary alkalinisation (give IV sodium bicarbonate to cause K+ depletion)
  • haemodialysis
  • haemofiltration
38
Q

What is the antidote to cyanide

A

Dicobalt edentate
Hydroxycobalamin
Nitrates

39
Q

Which patients are at higher risk of liver damage from paracetamol

A

Those with existing glutathione deficiency such as malnourished or co-existing liver disease

Enhanced cytochrome p450 system - alcoholics, St John’s Wort, Phenytoin, carbemazipine etc.

40
Q

What are common symptoms of poisoning

A

Nausea
Vomiting
Abdominal pain

41
Q

How soon after overdose should n-acetylcysteine be started

A

Within 8 hours if possible

42
Q

How do you manage a staggered paracetamol overdose

A

If they’ve taken over 75 mg/kg within the last 24 hour period, they should be treated with acetylcysteine
If it has been more than 24hrs since ingestion and their ALT and INR are fine, so are they
If abnormal - treat

43
Q

How does salicylate poisoning present

A 
Overdose of aspirin 
Respiratory alkalosis and metabolic acidosis 
N and V and haematemesis 
Tinnitus
Epigastric pain 
Sweating 
High HR, RR and temperature 
Non-cardiogenic pulmonary oedema
Reduced conscious level / seizures

Hypoglycaemia in children

44
Q

How do you treat salicylate overdose

A

Mild - Fluids
Moderate - Urinary alkalinisation
Severe - Haemodialysis

45
Q

Why should you not discharge someone immediately after giving naloxone

A

Naloxone’s half life is much shorter than that of opiates/oids
Therefore, once it wears off the person can go back into toxicity

46
Q

How do you treat cocaine toxicity

A

Benzos

47
Q

How do you treat amphetamine toxicity

A

Supportive to ensure adequate hydration

Benzodiazepines can be used for treatment of excitation, agitation or convulsions

48
Q

Why might somone who has taken ecstasy present with hyponatreamia

A

It causes hyperthermia and sweating so people drink a lot more
Some do this prophylactically
Worsened by the SIADH effect of ecstasy

49
Q

Can activated charcoal be used for alcohol poisoning

A

No

It does not absorb alcohol

50
Q

How do you manage ethanol poisoning

A

Supportive

Will recover once ingestion has ceased

51
Q

List symptoms and signs of methanol poisoning

A

Initial CNS effects which are similar to ethanol
Vertigo
Headache
Paraesthesia
Reduced visual acuity - driving in a snowstorm
Nausea, vomiting and abdominal pain
Eventual reduced consciousness and coma

52
Q

Where is ethylene glycol found

A

Common ingredient in commercial products such as coolants and antifreeze

53
Q

Serotonin syndrome is more likely if a patient is exposed to 2 or more drugs which cause increased stimulation of serotonergic synapses - true or false

A

True

e.g. SSRIs, MAOIs, tricyclics, cocaine etc

54
Q

List signs and symptoms of serotonin syndrome

A 
Agitation
Tremor
Hypertonia
Diaphoresis
Tachycardia 
Hyperpyrexia

Severe cases may be complicated with severe hyperthermia, rhabdomyolysis, renal failure and coagulopathies

55
Q

Why is it important to check U&Es in anticholinergic overdose

A

Risk of renal impairment and rhabdomyolysis

56
Q

Organophosphates can be absorbed through the skin - true or false

A

True

Must wear PPE when dealing with skin exposure and throughly decontaminate the patient

57
Q

How does carbon monoxide poisoning present

A 
Headache
Cherry red discoloration - only if very severe 
Malaise, lethargy 
Nausea 
SOB 
Tachycardia 
Neurological signs
Reduced consciousness
Seizures
58
Q

A carbon monoxide level of up to 15% is normal in smokers - true or false

A

False
Only up to 10%
Over 15% is indicative of significant exposure to CO

59
Q

How do you treat CO poisoning

A

Oxygen - as high a conc as possible

60
Q

How does b-blocker overdose present

A

Reduced BP and HR which may be severe enough to result in cardiogenic shock

Bronchospasm
CNS effects - convulsions, coma, resp depression

61
Q

How does calcium channel blocker overdose present

A

Myocardial depression, bradycardia and peripheral vasodilation producing profound hypotension and cardiogenic shock

Metabolic effects = acidosis, hyperglycaemia and kalaemia

62
Q

How do you treat calcium channel blocker overdose

A

Supportive
IV calcium chlroide
Insulin and dextrose infusion

63
Q

What can cause methaemoglobinaemia

A

Local anaesthetics
Antibiotics
Nitrites and nitrates

64
Q

What is methaemoglobin

A

An oxidised form of haemoglobin which is incapable of carrying O2

65
Q

How does methaemoglobinaemia present

A 
Persistant cyanosis despite adequate O2 delivery 
Slate-grey colouration
Headache, nausea 
Raised HR and RR
Coma 
Chocolate brown arterial blood
66
Q

What is the antidote to methaemoglobinaemia

A

Methylene blue solution

67
Q

Which type of drug typically causes acute dystonias

A

Antipsychotic or antiemetic drugs

68
Q

Which type of drug typically causes neuroleptic malignant syndrome

A

Antipsychotics

Doesnt need to be an overdose to occur

69
Q

How does neuroleptic malignant syndrome present

A 
Confusion
Rigidity
Tremor
Autonomic instability
Sweating and hyperpyrexia
70
Q

What is rhabdomyolysis

A

Breakdown of skeletal muscle causing the release of myoglobin
This can damage the kidneys

71
Q

What can cause rhabdomyolysis

A 
Prolonged immobilisation secondary to reduced consciousness
Status epilepticus or repeated seizures
Muscle hypertonicity
Hyperpyrexia
Excessive exercise
Direct effect of toxin i.e. colchicine
72
Q

What is the antidote to lignocaine overdose

A

Lipid emulsion

Acute Care (3 decks)

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