SPR L13 Acute Poisoning

Question 1

Learning Outcomes

Answer 1

• 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

Question 2

Poisoning - Background

Answer 2

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

Question 3

What are the different types of poisoning?

Answer 3

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

Question 4

Accidental Poisoning

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

Answer 4

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

Question 5

Contaminant poisoning

How can this come about?

Answer 5

• 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)

Question 6

Deliberate Malicious Poisoning

Describe this

Answer 6

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

Question 7

Who is at risk of deliberate self poisoning?

Answer 7

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

Question 8

Risk factors – for success in Deliberate Self Poisoning

Answer 8

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

Question 9

Outline the multidisciplincary approach to poisoning

Answer 9

• 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

Question 10

Overview of management

Give an overview of management of poisoning

Answer 10

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

Question 11

Initial Assessment – Medical Emergency

What should initial assessment for acute poisoning be?

Answer 11

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

Question 12

Airway

What actions should be taken?

Answer 12

• 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

Question 13

Breathing

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

Answer 13

1. Low resp rate common - Opiates, Alcohol, Benzodiazepines
2. –Metabolic acidosis

–Aspiration pneumonitis

Question 14

Circulation

What is common?

What should be carried out?

Answer 14

Hypotension common

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

Question 15

Disability

What is common?

What should be checked?

Answer 15

• 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!

Question 16

Exposure

Why is this necessary?

Answer 16

• 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

Question 17

What is important in History taking?

Answer 17

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

Tricyclic antidepressants: Cardiac Arrythmias, Convulsions, Coma

Question 18

Clinical Clues

What clues can you notice in the following…

1. Skin
2. Pupils

Answer 18

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)

Question 19

Clinical Clues

Give examples of clinical clues

Answer 19

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

Question 20

Common Toxic Syndromes

List these

Answer 20

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

Question 21

Investigations

​Outline how the following investigations can be useful

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

Answer 21

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

Question 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

Answer 22

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

Question 23

Symptomatic Treatment

Give examples of symptomatic treatment for acute poisoning

Answer 23

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

Question 24

Gastric Lavage

Outine this treatment method

Answer 24

• 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.

Question 25

What are the drugs that benefit from repeated activated charcoal?

Answer 25

* Carbamazepine * Theophylline * Phenobarbital * Quinine

Question 26

Haemodialysis is useful for which drugs?

Answer 26

* Salicylate * Lithium * Methanol / Ethylene glycol * Barbituates

Question 27

Increasing Elimination - how can this be achieved?

Answer 27

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

Question 28

Antidotes (know the ones in red) Name common antidotes and the poisons they counteract

Answer 28

See picture

Question 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?

Answer 29

* 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.

Question 30

**Opioid poisoning (Narcosis)** How is this treated?

Answer 30

* 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.

Question 31

What are the common pitfalls in managing acute poisoning?

Answer 31

* 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

Question 32

**‘Legal Highs’** Mephedrone Outline this drug

Answer 32

* 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

Question 33

**Summary**

Answer 33

* 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