Acute Poisoning - General Measures

It has been estimated that in the UK and USA over 10% of all acute adult medical admissions to hospital are due to acute poisoning.

• The most at risk groups are children under the age of 5 and females aged 15-44.¹
• About 4000 adults and <20 children die each year in the UK from acute poisoning.
• 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.

• Deliberate:
  • Overdose as self-harm or suicide attempt
  • Child abuse ± Munchausen'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

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

Resuscitation

Extent depends on state of patient, see Adult BLS and Paediatric BLS.

• 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 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).
  • 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 suspected give 0.8-2 mg naloxone iv/im every 2-3mins up to 10 mg until response (children: 10 mcg/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, MAOIs or salicylate.
    • Hypoglycaemia - insulin, oral hypoglycaemics, alcohol or salicylate.
  • Seizures - if prolonged/recurrent initially give diazepam 5-10 mg iv (Child: 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:²

• What was taken, how much, when, and by what route?
• Was alcohol consumed too?
• Any vomiting since ingestion?
• 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 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, 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).

• 12 lead electrocardiogram.
• U+E, lab glucose, anion gap ± lactate & osmolal gap.
• LFT & clotting
• Arterial blood gases.
• Drug levels (at appropriate interval: paracetamol, salicylates; others: theophylline, digoxin, lithium, anti-epileptics 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 suspected.
• Urinalysis - ?rhabdomyolysis, save sample for possible toxicological analysis.
• CXR if pulmonary oedema/aspiration suspected.
• CT brain may be needed to exclude other causes of alterations in conscious level.

• Head trauma (especially, in the ethanol-intoxicated patient)
• Stroke / SAH
• Meningitis
• Metabolic abnormalities (such as hypoglycemia, hyponatremia, or hypoxemia)
• Liver disease
• Post-ictal state

• Get more information:
  • UK National Poisons Information Centres 087 0600 6266³ (automatically routed to nearest centre)
  • Toxbase: NHSnet and internet-based info from the NPIC (registration free to NHS GPs and hospitals)⁴
  • Mims Colour index or TICTAC: to aid pill identification
  • BNF / Data Sheet Compendium
• Decontamination if appropriate:
  • Avoid contaminating yourself and wear protective clothing.
  • Ensure area is well-ventilated.
  • The patient should remove soiled clothing and wash him/herself if possible.
  • Put soiled clothing in a sealed container.
  • Wash all contaminated skin/hair with liberal amounts of warm water ±soap.
• Decrease absorption:
  • Gastric emptying - this is contraindicated if the airway is unprotected or overdose of corrosives or hydrocarbons taken. Complications include pulmonary aspiration and oesophageal perforation. Only 30% of gastric contents are returned and it is proven to be effective if within 1 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 - no longer recommended.
    • Gastric lavage - Place patient in left lateral head down (20°) position, insert large (36-40F) bore tube (children: 16 to 28F) into 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.
  • Activated charcoal (oral, naso-gastric tube) - its large surface area adsorbs many drugs (not iron, lithium, boric acid, cyanide, ethanol, ethylene glycol, methanol, malathion, DDT, carbamate, hydrocarbons, strong acids and alkalis). Ideally used in a 10:1 ratio with ingested drug, the usual dose is 50 g for an adult (children: 1 g/kg). Used sometimes with cathartic agents e.g. magnesium sulphate, lactulose or sorbitol (beware in young, old and renal insufficiency).
    Any oral antidotes given after charcoal may be rendered ineffective.
  • Whole bowel irrigation - uses large volume of an osmotically balanced, nonabsorbable polyethylene glycol electrolyte solution (e.g.Klean-Prep ®, GoLytely®). Used with iron, lithium, sustained-release or enteric-coated products, large ingestions, and ingested drug packets. Administer at 1 to 2L per hour po or NG (children: 30 ml/kg/hr), antiemetics may be required, continue until rectal effluent clear (approximately 3 to 6 hours). This is rarely used.
• Increase elimination:
  • Forced diuresis - no longer recommended.
  • Haemoperfusion and acid/alkaline diuresis - rarely used now.
  • Haemodialysis - severe salicylate, ethylene glycol, methanol, lithium, phenobarbital and chlorate poisonings.
  • Multiple doses of activated charcoal - interrupts enterohepatic or enteroenteric recirculation. Use 50g 4-hourly (children 1g/kg) or 12.5g hourly (children 0.25g/kg) to reduce vomiting, but beware severe constipation, fluid depletion and avoid repeating cathartic agent doses within 24hrs. Used with carbamazepine, dapsone, phenobarbital, quinine, salicylate, colchicine, dextropropoxyphene, digoxin, verapamil and theophylline overdoses.
• Supportive:
  • Maintain ABCDs
  • Observation and treatment of late complications: e.g. liver failure, rhabdomyolysis
• Specific antidote:
  • See individual articles for relevant antidotes and antagonists.

• 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.

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

Aim to establish:

• Intentions at time: Was the act planned? What precautions against being found? Did the patient seek help afterwards? Does the patient think the method was dangerous? Was there a final act (e.g. 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 50yrs old

• 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, chemicals which are not needed or out of date.
• Keep all medicines and chemicals in their original containers with clear label.