Paediatric Tox

Question 1

What are differences between paeds and adult toxicology?

Answer 1

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

Question 2

What is the mneumonic for drugs that can be seen on an xray?

Answer 2

COINS - chloral, calcium, opiate, iron, neuroleptics, sustained/coated release.
Button batteries

Question 3

List the 8 ‘one-pill can kill’ drugs in paeds tox.

Answer 3

CCB, TCA, chloroquines, opiates, sulfonylureas, BB, theophylline, amphetamines

Question 4

What is the potentially fatal dose of CCB?

Answer 4

15 mg/kg

Question 5

What are some key pearls about CCB toxicity?

Answer 5

Delayed onset (18-24 hours) of bradycardia, hypotension, conduction defects, refractory shock.

Question 6

Discuss chloroquines.

Answer 6

Coma, seizures, CV collapse. Cause sodium-channel blockade –> QRS widening. Hypokalaemia.
Cinchonism: blurred vision, hearing impairment, flushing. Severe: deafness, blindness, cardiac arrhythmias

Question 7

What is the potentially fatal dose of chloroquines?

Answer 7

20 mg/kg

Question 8

What is the potentially fatal dose of codeine and codone?

Answer 8

Codeine 10 mg/kg

Hydrocodone 1-5 mg/kg

Question 9

Discuss BB toxicity in children.

Answer 9

Can cause bradycardia but unlikely to have any physiological issues with this in children.

Bigger issue is the hypoglycaemia due to blockage of glycogenolysis.

Question 10

What is a potentially fatal dose of sulfonylurea?

Answer 10

0.1 mg/kg

Question 11

What is the typical onset of symptoms with sulfonylurea toxicity?

Answer 11

Delayed up to 18-24 hours

Question 12

What is the potentially fatal dose of TCAs in children?

Answer 12

15 mg/kg

Question 13

What are the classic ECG changes with TCA toxicity?

Answer 13

IV conduction delay leading to QRS widening (QTc does too), RAD, prominent R-wave in aVR

Question 14

What do the presence of ECG changes in patients with TCA toxicity herald?

Answer 14

Onset of ventricular arrhythmias and seizure activity

Question 15

What are the lethal non-drugs in paediatrics?

Answer 15

Organophosphates, carbamates. Paraquat/diquat. Hydrocarbons (solvents, eucalyptus oil, kerosene), camphor, corrosives, naphthalene, strychine

Question 16

What are the symptoms/signs of paraquat toxicity?

Answer 16

Burns, multiorgan failure and pulmonary fibrosis

Question 17

Discuss camphor toxicity.

Answer 17

5 ml of 100% can cause seizures, coma and hypotension.

Nausea/vomting first then delirium, hypotension, seizures, cerebral oedema.

Question 18

What is the potentially fatal dose of camphor?

Answer 18

50 mg/kg

Question 19

What is camphor found in?

Answer 19

In anti-itch, moth-repellent, cough suppressant and muscle soothers. Examples include tiger balm, vicks and vaporub.

Question 20

What is the toxicological issue with naphthalene?

Answer 20

One moth ball can lead to methaemoglobinaemia and haemolysis

Question 21

Where is strychnine found?

Answer 21

Typically in baits or pesticides. However, it sometimes is found mixed with LSD, heroin or cocaine.

Question 22

What is the mechanism of action of strychnine?

Answer 22

Antagonist at glycine and ACh receptors affecting motor nerve fibres in the spinal cord.

Question 23

What is the dose of activated charcoal in children?

Answer 23

1 mg/kg

Question 24

What is a significant dose of iron in paeds?

Answer 24

> 40 mg/kg

Question 25

What is the typical clinical course of iron toxicity?

Answer 25

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.

Question 26

Antidote in iron toxicity:

Answer 26

Deferrioxamine - chelating agent that forms a water-soluble desferrioxamine-iron complex

Question 27

When should a patient be considered for chelation in iron toxicity?

Answer 27

Serum [iron] > 90 mcg/ml or

>60 + visible tablets on xray or very symptomatic

Question 28

What is the dose of deferrioxamine?

Answer 28

15 mg/kg/hr IV not exceeding 80 mg/kg/24 hours.

Watch that urine output remains good.