Poisoning and overdose - overview

Disclaimer These guidelines have been produced to guide clinical decision making for the medical, nursing and allied health staff of Perth Children’s Hospital. They are not strict protocols, and they do not replace the judgement of a senior clinician. Clinical common-sense should be applied at all times. These clinical guidelines should never be relied on as a substitute for proper assessment with respect to the particular circumstances of each case and the needs of each patient. Clinicians should also consider the local skill level available and their local area policies before following any guideline.  Read the full CAHS clinical disclaimer.

Aim 

To guide PCH Emergency Department (ED) staff with the assessment and management of poisoning or overdose in children.

This guideline provides an outline of the general approach to poisoning. Specific information about poisoning presentations can be obtained from Poisons Information: 13 11 26 or refer to the Toxicology and Toxinology – Therapeutic Guidelines.

Background¹

• The vast majority of morbidity and mortality in toxicology arises from complication of the poisoning not the poisoning itself, particularly aspiration due to sedation
• Good supportive care is the best way to prevent complications
• Poisonings follow a highly predictable path
• Consider child protection concerns including intentional poisoning or neglectful supervision in significant and/or unusual overdose or if frequent concerning presentations.
• All ingestion presentations in children under 2 years must have an Early Childhood Injury Proforma completed (MR301.3) (internal WA Health only)

• Risk assessment is an essential cognitive step during assessment that outlines ongoing care

• If information is unclear always base the risk assessment upon a 'worse case scenario'
• Know your list of '2 pills can kill' in a toddler (see table 1 below)
  • Most accidental paediatric ingestions are only 1-2 tablets and a risk assessment will be low. Nevertheless, there are some toxins which can kill a young child with a very small exposure. These should be aggressively managed with early senior advice and/or toxicology service input.

The general approach to all poisonings should follow the RRSIDEAD format:

R Resuscitation
R Risk Assessment
S Supportive Care
I Investigations
D Decontamination
E Enhanced Elimination
A Antidotes
D Disposition

Management

• Early involvement of ED consultant and/or toxicologist is required for patents who:
  • require resuscitation
  • are a massive overdose / polypharmacy overdose
  • are assessed as high risk
  • have underlying medical conditions which may affect the pharmacokinetics of the ingested drug (e.g. renal disease, liver disease)
  • have ingested a drug which may have significant effect on an underlying medical condition (e.g. cardiac disease).

Resuscitation

Follow traditional ABC approach with modification:

• Airway
• Breathing
• Circulation
• Control/Correct
  • Seizures with midazolam – Medication Management Manual (internal WA Health only) (phenytoin contraindicated)
  • Hypothermia
  • Hyperthermia
    • Temperature > 38.5º requires core monitoring
    • Temperature > 39.5° is an indication for intubation, ventilation and paralysis.

Risk assessment

The following five factors will provide an accurate prediction of clinical course, potential complications and time coarse of poisoning to direct management.

1. Agent/s

2. Dose

3. Time of ingestion

• Use the latest possible time if uncertain

4. Patient factors

• Weight
• Comorbidities that may affect prognosis, for example:
  • Heart disease complicating calcium channel overdose
  • Morbid obesity affecting airway patency

5. Clinical status (features and progress)

• Agents commonly affect the autonomic, central nervous system (CNS) and neuromuscular systems and may produce a recognisable 'toxidrome'
• Does the clinical presentation of the patient fit with the predictable profile of the overdose?

Table 1: Toxidromes¹

		Anticholinergic	Sympathomimetic	Serotonergic
Examples		e.g. Antihistamines Antidepressants Antipsychotics Oxybutinin	e.g. Street amphetamines Dexamphetamine Methylphenidate	e.g. selective serotonin reuptake inhibitors / serotonin and noradrenaline reuptake inhibitors, tricyclic antidepressants, monoamine oxidase inhibitors
Autonomic	Vital Signs	Elevated	Elevated	Elevated
	Temperature	Elevated	Elevated	Elevated
	Pupils	Dilated	Dilated	Dilated
	Skin/mucous membranes	Flushed, dry	Flushed, sweaty	Flushed, sweaty
CNS	Mental status	Agitated, delirium	Agitated, euphoria	Agitated, coma
	Seizures	Rarely	Yes	Yes
Neuromuscular	Tone	Normal	Increased/rigidity	Increased/rigidity
	Reflexes	Normal	Hyperreflexic	Hyperreflexic/clonus
Complications		Urinary retention Hyperthermia Rhabdomyolysis Injury to self	Severe hypertension Myocardial infarction Pulmonary oedema Rhabdomyolysis Hyponatraemia Subarachnoid haemorrhage	Hyperthermia Rhabdomyolysis

Supportive care and monitoring¹

• Supportive care is tailored to the risk assessment and may involve:
  • IV hydration
  • Control of agitation and seizures with titrated benzodiazepines
  • Ensuring normoglycaemia
  • Bladder care (especially monitoring for urinary retention).

Investigations

Investigations are done for either specific purposes, to identify occult overdoses, or specific tests to determine the presence or level of a known ingestant.

Screening

• 12 lead Electrocardiogram (ECG)
  • Wide QRS (sodium channel blockade)
  • Long QT (potassium channel blockade, anti-psychotic overdose)
  • Heart blocks (calcium channel and beta blockers/calcium channel poisoning
• Serum Paracetamol level (4 hours)
• Blood glucose level (BGL).

Specific

• Drug levels
  • Paracetamol (in known ingestion)
  • Iron
  • Alcohols
  • Lithium
  • Salicylate
  • Theophylline
  • Anti-epileptics

Other adjunctive tests as indicated

• Blood gas:
  • High anion gap metabolic acidosis
    • Tricyclic antidepressants
    • Salicylates (late)
    • Iron
    • Toxic alcohol
    • Metformin
  • Respiratory alkalosis
    • Salicylates
  • Respiratory acidosis
    • Sedatives.

• Abdominal X-ray:
  • Confirmation of iron or other heavy metal ingestion.
• Blood tests:
  • Liver Function Tests (delayed paracetamol)
  • Urea Electrolytes and Creatinine
  • International Normalised Ratio (INR) (Warfarin, delayed paracetamol)

Decontamination¹

• Consider but rarely required
  • Activated charcoal
    • Will not bind to hydrocarbons or alcohol, corrosives and metals
    • Reserved for life threatening intoxications in which other measures are not expected to result in a good outcome
    • Contraindicated in un-intubated patient if decreased conscious level, vomiting or seizures are expected
    • Can be considered where the toxin is likely to remain in the gastrointestinal tract (generally within the first hour post ingestion for most agents)
  • Other methods: e.g. whole bowel irrigation - should not be instigated in the ED and should only be commenced on advice of Poisons Information.

Enhanced elimination

• Consider but rarely required
  • Techniques include: multiple dose activated charcoal, urinary alkalinisation, haemodialysis, haemofiltration, charcoal haemoperfusion.

Antidotes¹

• The risk assessment should determine if the potential benefit outweighs the possible adverse effects of the antidote.

Antidote	Poison
N-acetylcysteine	Paracetamol
Naloxone	Opiates
Flumazenil	Benzodiazapines
Desferrioxamine	Iron
Sodium Bicarbonate	Tricyclic antidepressants (TCA)

Disposition

• The disposition will be determined by:
  • The clinical risk assessment of the overdose
  • The psychiatric safety of the patient (for deliberate overdoses)
  • Other safety factors (parental neglect or drug use, domestic issues)
• Children should not be discharged home at night unless the risk assessment determines that the overdose is trivial and not requiring any form of observation.

Discharge home with parental supervision

• Trivial overdose with no requirement for observation
• Ensure safety issues such as accessibility to tablets are addressed and provide parents with Kidsafe resources
• Low risk overdose with minimal potential for deterioration during day-time hours
• Parents must be able to return to ED in the event of deterioration.

Emergency Short Stay Unit

• Accidental overdoses
• Stable patient with low-risk overdose requiring observation
• Low risk overdose with minimal potential for deterioration during night hours.

Medical ward

• Stable patient requiring medical or antidote therapy
• Any suspicion of non-accidental injury (NAI)

PCCU

• Unstable or intubated patient

Psychiatric ward

• Medically cleared patient deemed at risk of deliberate self harm

Nursing care

• Record a full set of observation on the Observation and Response Chart, with additional information to be recorded on the Clinical Comments chart.
• Record a full set of neurological observations.
• Frequency of observations can be dependent on the substance ingested.
• A minimum of hourly observations including full neurological observations (FNOs) should be recorded whilst in the ED.
• Any significant changes should be reported immediately to the medical team.
• Continuous cardiac monitoring if clinically indicated.
• Consider topical local anaesthetic e.g., lidocaine (lignocaine) with prilocaine (EMLA®) if an IV may be required.
• Strict, accurate fluid balance monitoring.
• Urinalysis for toxicology drug screen.
• Nursing care specific to the presentation.

Two Tablets - Potentially Lethal to a 10kg Child²

Agent	Principle features of severe toxicity
Amphetamines Amphetamine Metamphetamine MDMA (ecstacy)	Agitation Confusion Hypertension Hyperthermia
Baclofen	Coma
Calcium Channel Blockers Diltiazem CD Verapamil SR	Delayed onset of bradycardia Hypotension Conduction defects Refractory shock
Chloroquine Hydrochloroquine	Rapid onset of coma Seizures Cardiovascular collapse
Dextropropoxyphene	Ventricular tachycardia
Opioids Oxycodone Methadone Morphine Sulphate Diphenoxylate/Atropine	Coma, respiratory arrest Note: May be delayed with diphenoxylate/atropine and controlled release morphine
Propranolol	Coma Seizures Ventricular tachycardia Hypoglycaemia
Sulfonylureas Glibenclamide Glibenclamide/Metformin Gliclazide Glimepiride	Hypoglycaemia Note: Onset may be delayed up to eight hours.
Theophylline	Seizures Supraventricular tachycardia Vomiting
Tricyclic antidepressants Dothiepin	Coma Seizures Hypotension Ventricular tachycardia
Venlafaxine XR	Seizures

Non-pharmaceutical agents considered potentially lethal to children¹

Agent	Dose of concern for 10 kg child	Clinical effects
Organophosphate and carbamate insecticides	Single sip	Cholinergic symptoms Seizures Depressed level of consciousness
Paraquat/Diquat	Sip	Oro-pharyngeal burns Multiple organ failure Pulmonary fibrosis
Hydrocarbons Solvents Eucalyptus oil Kerosene	Sip	Rapid depressed level of consciousness Seizures Aspiration pneumonia
Camphor	5mL of 100%	Rapid depressed level of consciousness Seizures Hypotension
Corrosives Sodium hydroxide Strong acids		Gastro-oesophageal injury including perforation
Naphthalene	One mothball NB: Most mothballs contain paradichlorbenzene, which is non-toxic after a single accidental ingestion	Methaemoglobinaemia Haemolysis
Strychnine		Rapid onset of generalised muscle spasm Death by respiratory failure

Bibliography

1. Murray L, Little M, Pascu O and Hoggett K. Toxicology Handbook. 3rd Edition. Chatswood, NSW: Elsevier Australia; 2015. Available from: Toxicology Handbook - ClinicalKey (health.wa.gov.au) 
2. McCoubrie D, Murray L, Daly FFS and Little M. Toxicology case of the month: ingestion of two unidentified tablets by a toddler. Emerg Medicine J 2006; 23: 718-720
3. Bar-Oz B, Levichek Z and Koren G. Medications That Can Be Fatal For a toddler with One Tablet or Teaspoon. Paediatric Drugs 2004; 6 (2): 123-126

Endorsed by:	CAHS Drug and Therapeutics Committee	Date:	Apr 2024
		Review date:	Nov 2027

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