Paediatric toxicology

Introduction

• Children under 6yo managed as per this guideline. If older, manage as adults
• Risk assessment complicated by difficulty in obtaining history and different range of agents ingested by small children
• Most commonly in 12-36 month group
• Agents involved
  • Pharmaceuticals 40%
  • Household cleaning products 14%
  • Plants 13%
  • Cosmetics 10%
  • Pesticides 6%
• Toxic effects on a mg/kg basis are the same for children as for adults
• Typically take 1-3 tablets or a mouthful

Specific agents

• Low risk of significant toxicity in 1-3 dose units (amounts for 10kg toddler)
  • Paracetamol: Need >4 or >42mL liquid to exceed 200mg/kg
  • Iron: 6 or more tablets containing 105mg elemental iron to exceed 60mg/kg
  • Colchicine: >10x 500mcg tabs to exceed 0.5mg/kg
  • Digoxin: 16 or more 250mcg tabs to exceed 4mg
  • Anticoagulant rodenticides (<1 packet considered non-toxic following single unintentional ingestion)

Specific agents

• Potential for severe toxicity if 1-2 tabs ingested by 10kg toddler
  • Amphetamines
  • Baclofen
  • Calcium channel blockers
  • Camphor
  • Carbamazepine
  • Chloroquine
  • Clonidine
  • Clozapine

Specific agents

• Non-pharmaceuticals with potential for severe toxicity from one sip in 10kg toddler
  • Organophosphates and carbamate insecticides
  • Paraquat
  • Hydrocarbons: Solvents, eucalyptus oil, kerosone
  • Camphor
  • Corrosives: Sodium hydroxide, strong acids (all need oesophagoscopy)
  • Naphthalene (one moth ball)
    • Most moth balls contain paradichlorobenzene which is non-toxic after a single ingestion
  • Strychnine

Risk assessment

• Worst case scenario planning
  • Time of ingestion the latest possible time (except paracetamol)
  • Assume all missing or unaccounted for agents have been ingested
  • Do not attempt to account for spillage as this is dificult to estimate
  • If more than one child involved, assume each child has ingested all the missing or unaccounted for agent(s)

Risk assessment

• If entirely unknown agent e.g. picked up off ground in public, assume one of the potentially lethal agents
  • Admit minimum 12 hours observation period
  • IV access deferred unless early evidence of toxicity arises
  • Check BSL at presentation and at discharge (or if clinical signs)
  • Brief staff on signs to watch for: Agitation, ALOC, hypoglycaemia symptoms, seizures, cardiovascular instability
  • Monitor LOC, vital signs and early clinical features of hypoglycaemia
  • Cardiac monitoring if any abnormal conscious state or vital signs
  • Discharge in daylight hours

Non-toxic household exposures

• Inks
• Laxatives
• Matches
• Oral contraceptives
• Shampoo
• Shoe polish
• Silica
• Soap
• Thermometer mercury
• Vaseline

• Antacids
• Antibiotics
• Bath oil
• Candles
• Chalk
• Cigarette butts
• Colognes/perfume
• Cosmetics
• Deodorant
• Glues
• Fertiliser
• Hair products

Investigations

• Screening tests performed on adolescents/adults are NOT indicated
• Investigations are performed for specific purposes
• Early drug levels for paracetamol, digoxin or theophylline can exclude ingestion and obviate the need for prolonged observation, further investigation or transfer between facilities

Decontamination

• Unusual for this to be required
• If AC is warranted, mix with ice cream
• Administration of AC via NG inadvertently in bronchial tree has caused a paediatric death
• Should be reserved for severe or life-threatening poisoning where risk assessment suggests that supportive care +- antidote treatment will not ensure a satisfactory outcome
• Dose 1-2g/kg (50g in adult)
• Multiple-dose regime only for carbamazepine, dapsone, qunine, theophylline and phenobarbital

Enhanced elimination and antidotes

• Rarely warranted in paediatric exposures
• Doses of antidotes if indicated are on a mg/kg basis as for adults however antivenom is the same as adult dosing
  • Naloxone 0.01-0.1mg/kg then 0.01mg/kg/hr as required
  • Calcium chloride 10% 0.2ml/kg
  • Desferrioxamine 15mg/kg/hr for 12-24 hours
  • Ethanol 10mL/kg of 10% diluted in 5% glucose then 0.15mL/kg/hr to maintain blood ethanol level 100mg/dL
  • Fomepizole 15mg/kg over 30 minutes then 10mg/kg BD
  • Methylene blue 1-2mg/kg IV
  • Atropine 20-50mcg/kg every 15 minutes until secretions dry
  • Octreotide 1-2mcg/kg q8h
  • Sodium bicarbonate 1mmol/kg

Disposition

• <7% of cases are referred to hospital after poisons information centre discussion
• Most presentations can be discharged home if clinical intoxication does not develop over a short period of observation
• Circumstances of intoxication must be investigated and parents/carers advised on safe storage of medicines and chemicals in the household
• Always consider NAI (esp if <12 months old as not usually capable of self-administering anything)

Petroleum distillates

• Pneumonitis is the risk
• Need at least 6 hours observation and CXR
• There is a poor correlation between amount ingested and pulmonary toxicity
• Deliberate inhalation of petrols or paint can cause myocardial tissue toxicity with resultant arrhythmias (possibly due to sensitisation to endogenous catecholamines)

Essential oils

• Small amounts cause depression of conscious state, irritation of GI tract, liver dysfunction and pneumonitis if inhaled
• 5mL of eucalyptus oil and 15mL of turpentine can cause depressed conscious state

Iron

• >20mg/kg is toxic to children
• GI effects initially followed by cardiovascular in 6-24 hours then multiorgan failure and encephalopathy
• Whole bowel irrigation may be helpful
• Activated charcoal is not
• Chelation therapy should be guided by serum iron level and clinical status

Diphenoxylate-Atropine

• Combination drug used for diarrhea (Atropine just there to prevent abuse)
• Diphenoxylate is synthetic opioid converted to diphenoxine (5x as potent)
• In children:
  • 6 or more tabs = potentially lethal
  • More than 1 tablets can cause toxicity
  • One tablet does not require hospital referral
• Opioid effects usually manifest within hours but may recur after apparent improvement at 12-24 hours
• Anticholinergic effects usually masked by opioid effect
• AC warranted if present within 2 hours as may reduce naloxone requirement and LOS
• Observe minimum 12 hours if taken 2 or more tabs
• Resolution may take 48 hours

Last Updated on October 28, 2020 by Andrew Crofton