SPR L13 Acute Poisoning Flashcards Preview

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Flashcards in SPR L13 Acute Poisoning Deck (33):
1

Learning Outcomes

  • Key reading: BNF Emergency treatment of poisoning (p27-36), Integrated Pharmacology Chapter 24 (p627-644)
  • List the various types of poisoning
  • Discuss sources of information to assist treatment of a poisoning
  • Describe common toxic-syndromes and their treatment

2

Poisoning - Background

  • Acute poisoning is one of the most common reasons for hospital admission*
  • Low mortality in hospital
  • Different types

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3

What are the different types of poisoning?

  • Accidental / Non-accidental
  • Contaminant poisoning
  • Non-accidental poisoning as a form of child abuse
  • Deliberate malicious poisoning
  • Deliberate self poisoning
  • Recurrent deliberate self-poisoning

4

Accidental Poisoning

  1. Who is this seen in?
  2. Describe toxicity
  3. What should be considered?

  1. Often extremes of age child / elderly
  2. Often low toxicity
  3. Wide spectrum of substances – TOXBASE / NPIS - Assess the circumstances of the incident for both opportunity and prevention

5

Contaminant poisoning

How can this come about?

  • Localised
  • Accidental / terrorist
  • Water / Air supply
    • Heavy metals (old pipes / fish)
    • Organophosphates
    • Radioactive
      • e.g. Bhopal 1984 (Methyl Isocyanate gas)
      • Tokyo underground 1995 (Sarin gas)

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6

Deliberate Malicious Poisoning

Describe this

 

 

  • Rare
  • Often missed
  • Requires
    • Opportunity
    • Access to lethal substances
    • Psychopath

7

Who is at risk of deliberate self poisoning?

 

  • Adolescents and adults
  • Previous similar episodes
  • Psychiatric / psychosocial / personality disorder already identified
  • Triggers
  • Vary depending on availability
  • Wide variation in toxicity – CAUTION
  • Risk factors

8

Risk factors – for success in Deliberate Self Poisoning

  • Male
  • Older age group
  • Mental / physical illness
  • Social isolation
  • Unemployment
  • Alcoholism
  • Premeditated planning
  • Family history of suicide

9

Outline the multidisciplincary approach to poisoning

  • Nursing care – mainstay
  • Medical team
  • Medical toxicologist – TOXBASE / NPIS
  • Psychiatric liaison service
  • Proven to provide best care, efficient use of resources and reduced length of stay

10

Overview of management

Give an overview of management of poisoning

  • ABCDE - Resuscitation
  • Symptomatic treatment
  • Reduced absorption
  • Increased elimination
  • Consider specific Antidotes / trial of an antidote

11

Initial Assessment – Medical Emergency

What should initial assessment for acute poisoning be?

  • Initial impression
  • ABCDE and MOVE approach
  • History
  • ONLY PROGRESS TO FULL CLERK-IN ONCE PATIENT FULLY STABILISED

12

Airway

What actions should be taken?

  • Pen torch examination
  • Low threshold for intubation
  • Caution with the neck
  • May need airway adjunct
  • Oxygen unless paraquat (banned now, but still can occur - O2 free radicals concentrate in the lung)
  • Anti-emetics / NG tube

13

Breathing

  1. What is common?
  2. What may a high resp rate indicate?

  1. Low resp rate common - Opiates, Alcohol, Benzodiazepines

  2.  

    –Metabolic acidosis

    –Aspiration pneumonitis

14

Circulation

What is common?

What should be carried out?

Hypotension common

  • Iv access, bloods and fluids
  • Pulse and BP monitoring
  • ECG and cardiac monitoring

15

Disability

What is common?

What should be checked?

 

  • Decreased GCS common
  • Pupil size may be a useful clue

Must check glucose

  • Do not give activated charcoal if drowsy
  • No poison will cause asymmetrical signs!

16

Exposure

Why is this necessary?

  • Previous self harm or abuse
  • Hypothermia very common
  • Concurrent head injury
  • Skin / mucosal lesions
  • Coagulopathy

 

Never forget:  

Just because a patient is drunk or intoxicated does not mean that they   have no other pathology

17

What is important in History taking?

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  • Adults vs Children
  • Corroberative Hx
  • Ambulance crew
  • What?
  • When?
  • How much?

 

Tricyclic antidepressants: Cardiac Arrythmias, Convulsions, Coma

 

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18

Clinical Clues

What clues can you notice in the following...

  1. Skin
  2. Pupils

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  1. Cherry red (carbon monoxide), Blisters (barbituates), Needle tracks (opiate abuse), Burns esp mouth (caustics, corrosives)*
  2. Small (opiates, organophosphates, barbituates), Large (amphetamine, cocaine, TCA, atropine), Nystagmus (phenytoin, carbamazepine, barbituates), Blindness (quinidine and methanol)

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19

Clinical Clues

Give examples of clinical clues

  • Skin
  • Pupils
  • Behavioural disturbance (Anticholinergics, Solvents, hallucinogens)

  • Seizures (TCAs, Phenothiazines, Mefenamic acid, Theophyllines, Salicylates)

20

Common Toxic Syndromes

List these

  • Excess sedative / excess stimulant
  • Sympathomimetic syndrome
  • Opiates - Narcosis
  • Salicylism
  • Anticholinergic syndrome - vomiting, defecating, crying...
  • Cholinergic syndrome
  • Serotonin syndrome

21

Investigations

​Outline how the following investigations can be useful

  1. Blood tests
  2. Urine testing
    1. Give examples of specific urine tests

  1. U+E, LFTs, glucose, plasma osmolality, ABG (Calculate osmolar and anion gap from above), Paracetamol levels (+/- alcohol),Coagulation screen (liver)
  2. Toxicology screen
  3. Salicylates /Alcohol

    Digoxin

    Theophylline

    Methanol

    Ethylene glycol

    Lithium

    TCAs

    Barbituates

    Benzodiazepines

    Paraquat

22

Abnormal results

What can the following abnormal results be caused by?

  1. Hypoglycaemia
  2. Hypokalaemia
  3. Hyperkalaemia
  4. Prolonged PT
  5. Metabolic acidosis
  6. Increased plasma osmolality

  1. Insulin, oral hypoglycaemics, Ethanol
  2. Salbutamol, Theophylline, Salicylates
  3. Tissue necrosis /digoxin /renal failure, ACE inhibitors
  4. Warfarin, Paracetamol, Mushrooms
  5. Salicylates /Ethanol / methanol /TCAs
  6. Ethanol, methanol, ethylene glycol

23

Symptomatic Treatment

Give examples of symptomatic treatment for acute poisoning

  • Rewarming / cooling
  • Anticonvulsant therapy, diazepam, phenytoin, ventilation.
  • Anti-emetic therapy
  • Correction of fluid and electrolyte balance and hypoglycaemia.
  • Raising / Lowering blood pressure.
  • Pain relief

24

Gastric Lavage

Outine this treatment method

  • No clinical or experimental evidence of efficacy.
  • In some patients it may increase absorption and morbidity
  • Consider if life threatening amounts have been taken within the last 1-2 hours.

25

What are the drugs that benefit from repeated activated charcoal?

  • Carbamazepine
  • Theophylline
  • Phenobarbital
  • Quinine

26

Haemodialysis is useful for which drugs?

  • Salicylate
  • Lithium
  • Methanol / Ethylene glycol
  • Barbituates

27

Increasing Elimination - how can this be achieved?

  • Alkalinisation of the urine
    • Salicylates
    • TCA
    • Phenoxyacetate herbicides

28

Antidotes

(know the ones in red)

Name common antidotes and the poisons they counteract

See picture

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29

Paracetamol

 

At normal pharmacological doses extremely safe

However in excessive doses (overdose) the usual conjugation pathways become overwhelmed and the remaining paracetamol is oxidised to the toxic metabolite NAPBQI

  (N-Acetyl-p-benzoquinoneimine)

What is the treatment for OD?

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  • Antidote N-acetylcysteine IVI
  • Provides glutathione, allowing safe metabolism of NABQI
  • Should ideally be commenced within 12 hours of ingestion.
  • Interpret paracetamol levels / need for antidote according to nomogram
  • If in doubt treat / take care with staggered OD.

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30

Opioid poisoning (Narcosis)

How is this treated?

  • Sedation, respiratory depression, hypotension, pin-point pupils
  • Specific competitive antagonist at opiate receptor - Naloxone.
  • Given as 0.8-2.0 mg IV for adults repeated until effect seen.
  • If opiate poisoning is suspected may be given as a therapeutic trial before proceeding to endotracheal intubation.
  • Usually rapid response.
  • May precipitate withdrawal in addicts.
  • Shorter duration of action than many opiates, therefore repeated doses or infusion may be necessary.

31

What are the common pitfalls in managing acute poisoning?

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  • Underestimating Psychosocial Risk
  • Underestimating Toxin Risk - especially TCA overdose - ECG important
  • Miscalculating N-Acetyl cysteine regimen
    • Anaphylactoid reaction relatively common

    • Always double check your calculations with someone-else 

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32

‘Legal Highs’

Mephedrone

Outline this drug

  • 4-MMC, MM-Cat (Meow Meow, plant food, bubbles)
  • Synthetic stimulant similar euphoria as MDMA
  • Reported adverse effects
    • Nose-bleeds
    • Vomiting
    • Tachycardia
    • Headaches
    • Chest pain
    • Anxiety attacks
    • Hallucinations

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33

Summary

  • Poisoning and drug abuse are a common attendance to hospital
  • A general supportive approach is all that is needed for most
  • Use Toxbase, BNF and other sources of info to guide management
  • Watch out for common mistakes
  • Keep up to date