Paediatric Tox Flashcards
What are differences between paeds and adult toxicology?
Anatomy: weight variation, larger body surface area, thinner skin (more absorption), smaller airways (so inhalation more toxic) and higher TBW (VOD is different).
Physiology: greater minute volume (inhalants), tachycardia results in increased CO rather than SV (quick decompensation), immature kidney/liver (affects elimination), lower liver glycogen (hypoglycaemic quickly), BBB more permeable (CNS toxicity greater), neonatal withdrawal syndrome
What is the mneumonic for drugs that can be seen on an xray?
COINS - chloral, calcium, opiate, iron, neuroleptics, sustained/coated release.
Button batteries
List the 8 ‘one-pill can kill’ drugs in paeds tox.
CCB, TCA, chloroquines, opiates, sulfonylureas, BB, theophylline, amphetamines
What is the potentially fatal dose of CCB?
15 mg/kg
What are some key pearls about CCB toxicity?
Delayed onset (18-24 hours) of bradycardia, hypotension, conduction defects, refractory shock.
Discuss chloroquines.
Coma, seizures, CV collapse. Cause sodium-channel blockade –> QRS widening. Hypokalaemia.
Cinchonism: blurred vision, hearing impairment, flushing. Severe: deafness, blindness, cardiac arrhythmias
What is the potentially fatal dose of chloroquines?
20 mg/kg
What is the potentially fatal dose of codeine and codone?
Codeine 10 mg/kg
Hydrocodone 1-5 mg/kg
Discuss BB toxicity in children.
Can cause bradycardia but unlikely to have any physiological issues with this in children.
Bigger issue is the hypoglycaemia due to blockage of glycogenolysis.
What is a potentially fatal dose of sulfonylurea?
0.1 mg/kg
What is the typical onset of symptoms with sulfonylurea toxicity?
Delayed up to 18-24 hours
What is the potentially fatal dose of TCAs in children?
15 mg/kg
What are the classic ECG changes with TCA toxicity?
IV conduction delay leading to QRS widening (QTc does too), RAD, prominent R-wave in aVR
What do the presence of ECG changes in patients with TCA toxicity herald?
Onset of ventricular arrhythmias and seizure activity
What are the lethal non-drugs in paediatrics?
Organophosphates, carbamates. Paraquat/diquat. Hydrocarbons (solvents, eucalyptus oil, kerosene), camphor, corrosives, naphthalene, strychine
What are the symptoms/signs of paraquat toxicity?
Burns, multiorgan failure and pulmonary fibrosis
Discuss camphor toxicity.
5 ml of 100% can cause seizures, coma and hypotension.
Nausea/vomting first then delirium, hypotension, seizures, cerebral oedema.
What is the potentially fatal dose of camphor?
50 mg/kg
What is camphor found in?
In anti-itch, moth-repellent, cough suppressant and muscle soothers. Examples include tiger balm, vicks and vaporub.
What is the toxicological issue with naphthalene?
One moth ball can lead to methaemoglobinaemia and haemolysis
Where is strychnine found?
Typically in baits or pesticides. However, it sometimes is found mixed with LSD, heroin or cocaine.
What is the mechanism of action of strychnine?
Antagonist at glycine and ACh receptors affecting motor nerve fibres in the spinal cord.
What is the dose of activated charcoal in children?
1 mg/kg
What is a significant dose of iron in paeds?
> 40 mg/kg
What is the typical clinical course of iron toxicity?
Initial period: nausea/vomiting, diarrhoea, abdo pain, hypotension, haematemesis and fever.
Latent period of 6-24 hours where symptoms seem to improve. Then later symptoms: tachycardia, vasoconstriction, shock, metabolic acidosis.
Multiorgan failure occurs >48 hours post-exposure.
Antidote in iron toxicity:
Deferrioxamine - chelating agent that forms a water-soluble desferrioxamine-iron complex
When should a patient be considered for chelation in iron toxicity?
Serum [iron] > 90 mcg/ml or
>60 + visible tablets on xray or very symptomatic
What is the dose of deferrioxamine?
15 mg/kg/hr IV not exceeding 80 mg/kg/24 hours.
Watch that urine output remains good.
