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Pharmacology > SPR L13 Acute Poisoning > Flashcards

SPR L13 Acute Poisoning Flashcards

1
Q

Learning Outcomes

A
  • 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
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2
Q

Poisoning - Background

A
  • Acute poisoning is one of the most common reasons for hospital admission*
  • Low mortality in hospital
  • Different types
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3
Q

What are the different types of poisoning?

A
  • Accidental / Non-accidental
  • Contaminant poisoning
  • Non-accidental poisoning as a form of child abuse
  • Deliberate malicious poisoning
  • Deliberate self poisoning
  • Recurrent deliberate self-poisoning
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4
Q

Accidental Poisoning

  1. Who is this seen in?
  2. Describe toxicity
  3. What should be considered?
A
  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
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5
Q

Contaminant poisoning

How can this come about?

A
  • 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
Q

Deliberate Malicious Poisoning

Describe this

A
  • Rare
  • Often missed
  • Requires
    • Opportunity
    • Access to lethal substances
    • Psychopath
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7
Q

Who is at risk of deliberate self poisoning?

A
  • Adolescents and adults
  • Previous similar episodes
  • Psychiatric / psychosocial / personality disorder already identified
  • Triggers
  • Vary depending on availability
  • Wide variation in toxicity – CAUTION
  • Risk factors
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8
Q

Risk factors – for success in Deliberate Self Poisoning

A
  • Male
  • Older age group
  • Mental / physical illness
  • Social isolation
  • Unemployment
  • Alcoholism
  • Premeditated planning
  • Family history of suicide
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9
Q

Outline the multidisciplincary approach to poisoning

A
  • 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
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10
Q

Overview of management

Give an overview of management of poisoning

A
  • ABCDE - Resuscitation
  • Symptomatic treatment
  • Reduced absorption
  • Increased elimination
  • Consider specific Antidotes / trial of an antidote
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11
Q

Initial Assessment – Medical Emergency

What should initial assessment for acute poisoning be?

A
  • Initial impression
  • ABCDE and MOVE approach
  • History
  • ONLY PROGRESS TO FULL CLERK-IN ONCE PATIENT FULLY STABILISED
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12
Q

Airway

What actions should be taken?

A
  • 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
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13
Q

Breathing

  1. What is common?
  2. What may a high resp rate indicate?
A
  1. Low resp rate common - Opiates, Alcohol, Benzodiazepines
  2. –Metabolic acidosis

–Aspiration pneumonitis

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14
Q

Circulation

What is common?

What should be carried out?

A

Hypotension common

  • Iv access, bloods and fluids
  • Pulse and BP monitoring
  • ECG and cardiac monitoring
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15
Q

Disability

What is common?

What should be checked?

A
  • 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!
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16
Q

Exposure

Why is this necessary?

A
  • 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
Q

What is important in History taking?

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

Tricyclic antidepressants: Cardiac Arrythmias, Convulsions, Coma

18
Q

Clinical Clues

What clues can you notice in the following…

  1. Skin
  2. Pupils
A
  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)
19
Q

Clinical Clues

Give examples of clinical clues

A
  • Skin
  • Pupils
  • Behavioural disturbance (Anticholinergics, Solvents, hallucinogens)
  • Seizures (TCAs, Phenothiazines, Mefenamic acid, Theophyllines, Salicylates)
20
Q

Common Toxic Syndromes

List these

A
  • Excess sedative / excess stimulant
  • Sympathomimetic syndrome
  • Opiates - Narcosis
  • Salicylism
  • Anticholinergic syndrome - vomiting, defecating, crying…
  • Cholinergic syndrome
  • Serotonin syndrome
21
Q

Investigations

​Outline how the following investigations can be useful

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

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
A
  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
Q

Symptomatic Treatment

Give examples of symptomatic treatment for acute poisoning

A
  • 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
Q

Gastric Lavage

Outine this treatment method

A
  • 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
Q

What are the drugs that benefit from repeated activated charcoal?

A
  • Carbamazepine
  • Theophylline
  • Phenobarbital
  • Quinine
26
Q

Haemodialysis is useful for which drugs?

A
  • Salicylate
  • Lithium
  • Methanol / Ethylene glycol
  • Barbituates
27
Q

Increasing Elimination - how can this be achieved?

A
  • Alkalinisation of the urine
    • Salicylates
    • TCA
    • Phenoxyacetate herbicides
28
Q

Antidotes

(know the ones in red)

Name common antidotes and the poisons they counteract

A

See picture

29
Q

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?

A
  • 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.
30
Q

Opioid poisoning (Narcosis)

How is this treated?

A
  • 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
Q

What are the common pitfalls in managing acute poisoning?

A
  • 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
32
Q

‘Legal Highs’

Mephedrone

Outline this drug

A
  • 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
33
Q

Summary

A
  • 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

Pharmacology (26 decks)

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