Epidemiology¹

There are more than 140,000 cases of poisoning admitted to NHS hospitals every year.² There has been a slight reduction in admissions in recent years, possibly due to Government campaigns aimed and the reduction of suicide and self-harm and the withdrawal of drugs such as co-proxamol.³

• The most at-risk groups are children under the age of 5⁴ and females aged 35-54 (4.4 deaths per 100,000 UK population in 2009).¹
• The overall UK mortality rate from acute poisoning was 28 per million population in 2009, demonstrating an increasing trend over the previous eight years.
• The incidence of acute poisoning in children under the age of 5 is reducing due to the introduction of initiatives such as blister packs and other safety measures.⁴
• The age-standardised rate for suicide due to poisoning fell by 40% between 2001 and 2007, from 30 to 18 deaths per million population. Since 2007, the rate has remained stable, rising only slightly to 19 deaths per million population in 2009.
• The most common type of toxin ingested varies geographically, being prescribed medication in the developed countries and agricultural chemicals, hydrocarbons or traditional medicines in the developing nations.

Most of the discussion below is confined to drug and chemical poisoning.

Types of poisoning

• Deliberate:
  • Overdose as self-harm or suicide attempt.
  • Child abuse ± fabricated or induced illness by carers (formerly referred to as Münchhausen's syndrome by proxy).
  • Third party (attempted homicide, terrorist, warfare).
• Accidental:
  • Most episodes of paediatric poisoning.
  • Dosage error:
    • Iatrogenic
    • Patient error
  • Recreational use.
• Environmental:
  • Plants
  • Food
  • Venomous stings/bites
• Industrial exposures.

General management^5,6

See specific management dependent on drug(s) involved (contact poisons centre or Toxbase® for current specific advice).

Resuscitation⁷

Extent depends on the state of the patient - see Adult Basic Life Support⁸ and Paediatric Basic Life Support.⁹

• Airway :
  • Open, suction, maintain and intubate as necessary.
• Breathing:
  • Assess work and effectiveness of ventilation.
  • Give oxygen ± assisted ventilation (avoid mouth-to-mouth).
  • Respiratory depression - consider opiates, benzodiazepines, early salicylate poisoning.
  • Tachypnoea - consider metabolic acidosis, e.g. salicylates, methanol.
• Circulation:
  • Attach a cardiac monitor, assess pulse, blood pressure and perfusion. Establish intravenous (IV) access.
  • Tachycardia/irregular pulse - consider overdose of salbutamol, antimuscarinics, tricyclics, quinine, phenothiazine, chloral hydrate, cardiac glycosides, amfetamines and theophylline poisoning.
  • If hypotensive, consider giving fluid bolus (colloid) or, if necessary, inotropes.
• Disability:
  • Assess consciousness level (Glasgow Coma Scale or AVPU (= Alert, Voice, Pain, Unresponsive)).
  • Coma may suggest benzodiazepines, alcohol, opiates, tricyclics, or barbiturates.
  • Check pupils and eye movements:
    • Large - consider anticholinergics, sympathomimetics, tricyclics.
    • Small - consider opiates or cholinergics.
    • If opiates are suspected, give 0.8-2 mg naloxone IV/intramuscularly (IM) every 2-3 minutes up to 10 mg until response (children: 10 micrograms/kg IV/IM repeated up to 0.2 mg/kg); repeated doses may be required thereafter, as it has a shorter half-life than most opiates.
    • Unreactive - causes include barbiturates, carbon monoxide, hydrogen sulphide, cyanide/cyanogens, head injury/hypoxia.
    • Unequal - slight variation can be normal - but consider head injury.
    • Strabismus - can be seen with carbamazepine overdose.
    • Papilloedema - associated with methanol, carbon monoxide and glutethimide.
    • Nystagmus - seen with CNS acting agents, e.g. phenytoin.
  • Check blood glucose - if hypoglycaemic, give 50 ml 50% dextrose IV (children: 5 ml/kg of 10% dextrose IV).
    • Hyperglycaemia - organophosphates, theophyllines, monoamine oxidase inhibitors (MAOIs) or salicylate.
    • Hypoglycaemia - insulin, oral hypoglycaemics, alcohol or salicylate.
  • Seizures - if prolonged/recurrent, initially give diazepam 5-10 mg IV (children: 0.25-0.4 mg/kg IV or PR) or midazolam (0.15 mg/kg) IM/IV. Many drugs can induce seizures, including tricyclics, theophylline, opiates, cocaine and amfetamines.

History

This may be unreliable but include the following:

• What was taken, how much, when and by what route?
• Was alcohol consumed too?
• Any vomiting since ingestion?
• Establish past medical history, current medications and allergies.
• Was a suicide note left?
• Is the patient pregnant?
• Histories from others including: family, friends, paramedics, police and observers.

Obtain the patient's past medical notes if possible.

General examination

• Directed cardiovascular, respiratory, abdominal and neurological examination.
• Vital signs, pupils, etc. mentioned in 'Resuscitation' section, above.
• Temperature - hypothermia (phenothiazines, barbiturates, or tricyclics) or hyperthermia (amfetamines, ecstasy, MAOIs, cocaine, antimuscarinics, theophylline, serotonin syndrome).
• Muscle rigidity (ecstasy, amfetamines).
• Skin - cyanosis (methaemoglobinaemia), very pink (carboxyhaemoglobinaemia, cyanide, hydrogen sulphide), blisters (barbiturates, tricyclic antidepressants (TCAs), benzodiazepines), needle tracks, hot/flushed (anticholinergics).
• Breath - ketones (diabetic/alcoholic ketoacidosis), "bitter almonds" (cyanide), "garlic-like" (organophosphates, arsenic), "rotten eggs" (hydrogen sulphide), organic solvents.
• Mouth - perioral acneiform lesions (solvent abuse), dry mouth (anticholinergics), hypersalivation (parasympathomimetics).

Investigations

• 12-lead electrocardiogram.
• U+E, laboratory glucose, anion gap ± lactate and osmolal gap.
• LFTs and clotting.
• Arterial blood gases.
• Paracetamol level (also salicylates,¹⁰ theophylline, digoxin, lithium, antiepileptics - if it was likely that they had been taken).
• Comprehensive toxicology screens not normally indicated in the emergency treatment.
• Carboxyhaemoglobin levels if carbon monoxide poisoning is suspected.
• Urinalysis - query rhabdomyolysis; save sample for possible toxicological analysis.
• CXR if pulmonary oedema/aspiration suspected.
• CT scan of the brain may be needed to exclude other causes of alterations in conscious level.

Differential diagnosis

• Head trauma (especially, in the ethanol-intoxicated patient).
• Stroke/subarachnoid haemorrhage (SAH).
• Meningitis.
• Metabolic abnormalities (such as hypoglycaemia, hyponatraemia, or hypoxaemia).
• Liver disease.
• Post-ictal state

Treatment^5,6

• Get more information:
  • UK National Poisons Information Centres 087 0600 6266¹¹ (automatically routed to nearest centre).
  • Toxbase®: NHS intranet and internet-based information from the National Poisons Information Centre (registration free to NHS GPs and hospitals).¹²
  • Mims Colour index or TICTAC (a computer-aided tablet and capsule identification system available to authorised users, including Regional Drug Information Centres and Poisons Information Centres.): to aid pill identification.
  • British National Formulary (BNF)/Data Sheet Compendium.
• Decontamination if appropriate:
  • Avoid contaminating yourself and wear protective clothing.
  • Ensure the area is well-ventilated.
  • The patient should remove soiled clothing and wash himself/herself if possible.
  • Put soiled clothing in a sealed container.
  • Wash all contaminated skin/hair with liberal amounts of warm water ± soap.
• Decrease absorption:
  • Single-dose activated charcoal is the preferred method of decontamination in many cases. Patients should have had a significant overdose, be co-operative, without impairment of consciousness and not thought to be likely to fit imminently. Ideally it is used in a 10:1 ratio with the ingested drug - the usual dose is 50 g for an adult (children: 1 g/kg). It may be repeated in one hour if necessary (oral, nasogastric tube). Its large surface area adsorbs many drugs, but has its limitations. It may not be be effective if given after the first hour or in cases of poisoning with iron, lithium, boric acid, cyanide, ethanol, ethylene glycol, methanol, malathion, DDT, carbamate, hydrocarbon or strong acids or alkalis.
    
    Any oral antidotes given after charcoal may be rendered ineffective.
  • Gastric emptying is contra-indicated if the airway is unprotected or an overdose of corrosives or hydrocarbons has been taken. Complications include pulmonary aspiration and oesophageal perforation. Only 30% of gastric contents are returned and it is proven to be effective if within one hour of ingestion (so this is only generally done if patients present early having taken a potentially fatal dose of drug). Controversially, this is sometimes extended if delayed gastric emptying (e.g. presence of coma or overdose of tricyclics or salicylates) is thought likely.
    • Emesis is no longer recommended.
    • Gastric lavage is used in cases where medications have been ingested that activated charcoal would absorb poorly (e.g. iron, lithium) and for sustained-release formulations or enteric-coated tablets. It is carried out by placing the patient in left lateral head down (20°) position, inserting a large (36-40F) bore tube (children: 16-28F) into the stomach. Remove contents with sequential administration and aspiration of small (200-300 ml) quantities of warm water or saline (children: 10-20 ml/kg preferably saline). Alternatively, the stomach contents can just be aspirated.
  • Whole bowel irrigation is also useful in cases where poisoning is due to substances which would not be absorbed by activated charcoal. It uses a large volume of an osmotically balanced, nonabsorbable polyethylene glycol electrolyte solution (e.g. Klean-Prep®, GoLYTELY®). Used with iron and other heavy metals, lithium, sustained-release or enteric-coated products, large ingestions and ingested drug packets. Administer at 1-2 L per hour PO or NG (children: 30 ml/kg/hour), antiemetics may be required, continue until rectal effluent is clear (approximately 3-6 hours). This is rarely used.
• Increase elimination:
  • Multiple doses of activated charcoal - interrupts enterohepatic or enteroenteric recirculation. Use 50 g 4-hourly (children 1 g/kg) or 12.5 g hourly (children 0.25 g/kg) to reduce vomiting but beware severe constipation and fluid depletion. Used with carbamazepine, dapsone, phenobarbital, quinine, salicylate, colchicine, dextropropoxyphene, digoxin, verapamil and theophylline overdoses.
  • Forced diuresis - no longer recommended.
  • Haemoperfusion and acid/alkaline diuresis - rarely used now.
  • Haemodialysis - severe salicylate, ethylene glycol, methanol, lithium, phenobarbital and chlorate poisonings.
• Supportive:
  • Maintain ABCDs.
  • Observation and treatment of late complications, e.g. liver failure, rhabdomyolysis.
• Specific antidote:
  • See individual articles for relevant antidotes and antagonists.

Referral

• Medical/paediatric - for continued support/antidote administration, observation, cardiac monitoring.
• Psychiatric - for all deliberate self-poisonings, those with suicidal ideation and if the country's Mental Health Act has been employed to detain/treat.

Psychiatric assessment

Be sympathetic despite the hour! Interview relatives and friends if possible.

Aim to establish:

• Intentions at the time: establish whether the act was planned. What precautions were taken against being found? Did the patient seek help afterwards? Does the patient think the method was dangerous? Was there a final act (e.g. a suicide note)?
• What problems led to the act: do they still exist?
• Was the act aimed at someone?
• Is there a psychiatric disorder (depression, alcoholism, personalty disorder, schizophrenia, dementia)?
• What are his resources (friends, family, work, personality)?
• Present intentions and suicide risk. The following factors increase the chance of future suicide:
  • Original intention was to die.
  • Present intention is to die.
  • Presence of psychiatric disorder.
  • Poor resources.
  • Previous suicide attempts.
  • Socially isolated.
  • Unemployed.
  • Male.
  • Over 50 years old.

Prevention

• Adult education.
• Double-check dosage before administration.
• Vigilance by health professionals to recognise the early signs of abuse and potential suicide.
• Put all medicines and household chemicals in a locked child-proof cupboard >1.5 metres off the ground.
• Safely dispose of medicines and chemicals which are not needed or are out of date.
• Keep all medicines and chemicals in their original containers with clear labels.

Document references

1. Injury and Poisoning Mortality, 2009, Office for National Statistics (2011)
2. National Poisons Information Service: Resources - Acute Poisoning, Health Protection Agency (2011)
3. National Poisons Information Service 2009/10 Annual Report and Five Year Review, Health Protection Agency (2010)
4. Development of a UK Children's Environment and Health Strategy, Health Protection Agency (2008)
5. Frithsen IL, Simpson WM Jr; Recognition and management of acute medication poisoning. Am Fam Physician. 2010 Feb 1;81(3):316-23. [abstract]
6. McGregor T, Parkar M, Rao S; Evaluation and management of common childhood poisonings. Am Fam Physician. 2009 Mar 1;79(5):397-403. [abstract]
7. Soar J et al; European Resuscitation Council Guidelines for Resuscitation 2010 Section 8. Cardiac arrest in special circumstances: Electrolyte abnormalities, poisoning, drowning, accidental hypothermia, hyperthermia, asthma, anaphylaxis, cardiac surgery, trauma, pregnancy, electrocution, 2010.
8. Adult Basic Life Support, Resuscitation Council UK Guideline (2010)
9. Paediatric Basic Life Support, Resuscitation Council UK Guideline (2010)
10. Meyers L; Is there a need to check salicylate levels in overdose patients who deny having ingested salicylates? BestBETs, 2008
11. National Poisons Information Service
12. Toxbase®; (Registration is free for doctors who are employed by an NHS practice)