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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
When do you calculate the anion gap
If you need to determine the cause of a metabolic acidosis
26
List causes of a raised anion gap
``` MUDPILES Methanol Uraemia Paraaldehyde Diabetic ketoacidosis Iron overdose Lactic acid Ethylene glycol Salicylate ```
27
How is activated charcoal used in overdose
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
28
What is the most common cause of overdose in the West
Paracetamol
29
What is considered a safe dose of paracetamol
75mg/kg or less 75-100 is potentially toxic and over this is likely toxic
30
N-actylcysteine is a fast acting treatment - true or false
False | Takes up to 21 hours to deliver a dose
31
What is the antidote to tricyclic antidepressant overdose
Sodium bicarbonate
32
What is the antidote to beta blocker overdose
Glucagon - IV 5-10mg
33
What is the antidote to opioid overdose
Naloxone IM or IV Titrate up to response - look for a rise in RR
34
What is the antidote to ethylene glycol or methanol overdose
Ethanol Fomepizole - inhibits dehydrogenase Give sodium bicarb if acidotic
35
What is the antidote to iron salts overdose
Desferrioxamine
36
What is the antidote to organophosphate overdose
Atropine - to reduce bronchial secretions/spasm | Pralidoxime mesylate
37
How can you enhance the elimination of a toxic substance
Enhance or augment renal function - urinary alkalinisation (give IV sodium bicarbonate to cause K+ depletion) - haemodialysis - haemofiltration
38
What is the antidote to cyanide
Dicobalt edentate Hydroxycobalamin Nitrates
39
Which patients are at higher risk of liver damage from paracetamol
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
What are common symptoms of poisoning
Nausea Vomiting Abdominal pain
41
How soon after overdose should n-acetylcysteine be started
Within 8 hours if possible
42
How do you manage a staggered paracetamol overdose
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
How does salicylate poisoning present
``` 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
How do you treat salicylate overdose
Mild - Fluids Moderate - Urinary alkalinisation Severe - Haemodialysis
45
Why should you not discharge someone immediately after giving naloxone
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
How do you treat cocaine toxicity
Benzos
47
How do you treat amphetamine toxicity
Supportive to ensure adequate hydration | Benzodiazepines can be used for treatment of excitation, agitation or convulsions
48
Why might somone who has taken ecstasy present with hyponatreamia
It causes hyperthermia and sweating so people drink a lot more Some do this prophylactically Worsened by the SIADH effect of ecstasy
49
Can activated charcoal be used for alcohol poisoning
No | It does not absorb alcohol
50
How do you manage ethanol poisoning
Supportive | Will recover once ingestion has ceased
51
List symptoms and signs of methanol poisoning
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
Where is ethylene glycol found
Common ingredient in commercial products such as coolants and antifreeze
53
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
True | e.g. SSRIs, MAOIs, tricyclics, cocaine etc
54
List signs and symptoms of serotonin syndrome
``` Agitation Tremor Hypertonia Diaphoresis Tachycardia Hyperpyrexia ``` Severe cases may be complicated with severe hyperthermia, rhabdomyolysis, renal failure and coagulopathies
55
Why is it important to check U&Es in anticholinergic overdose
Risk of renal impairment and rhabdomyolysis
56
Organophosphates can be absorbed through the skin - true or false
True | Must wear PPE when dealing with skin exposure and throughly decontaminate the patient
57
How does carbon monoxide poisoning present
``` Headache Cherry red discoloration - only if very severe Malaise, lethargy Nausea SOB Tachycardia Neurological signs Reduced consciousness Seizures ```
58
A carbon monoxide level of up to 15% is normal in smokers - true or false
False Only up to 10% Over 15% is indicative of significant exposure to CO
59
How do you treat CO poisoning
Oxygen - as high a conc as possible
60
How does b-blocker overdose present
Reduced BP and HR which may be severe enough to result in cardiogenic shock Bronchospasm CNS effects - convulsions, coma, resp depression
61
How does calcium channel blocker overdose present
Myocardial depression, bradycardia and peripheral vasodilation producing profound hypotension and cardiogenic shock Metabolic effects = acidosis, hyperglycaemia and kalaemia
62
How do you treat calcium channel blocker overdose
Supportive IV calcium chlroide Insulin and dextrose infusion
63
What can cause methaemoglobinaemia
Local anaesthetics Antibiotics Nitrites and nitrates
64
What is methaemoglobin
An oxidised form of haemoglobin which is incapable of carrying O2
65
How does methaemoglobinaemia present
``` Persistant cyanosis despite adequate O2 delivery Slate-grey colouration Headache, nausea Raised HR and RR Coma Chocolate brown arterial blood ```
66
What is the antidote to methaemoglobinaemia
Methylene blue solution
67
Which type of drug typically causes acute dystonias
Antipsychotic or antiemetic drugs
68
Which type of drug typically causes neuroleptic malignant syndrome
Antipsychotics | Doesnt need to be an overdose to occur
69
How does neuroleptic malignant syndrome present
``` Confusion Rigidity Tremor Autonomic instability Sweating and hyperpyrexia ```
70
What is rhabdomyolysis
Breakdown of skeletal muscle causing the release of myoglobin This can damage the kidneys
71
What can cause rhabdomyolysis
``` Prolonged immobilisation secondary to reduced consciousness Status epilepticus or repeated seizures Muscle hypertonicity Hyperpyrexia Excessive exercise Direct effect of toxin i.e. colchicine ```
72
What is the antidote to lignocaine overdose
Lipid emulsion

Acute Care (3 decks)

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