Poisoning

Question 1

What are the features of accidental poisoning

Answer 1

Usually when a young child is found playing with tablets or household/garden substances or with some in their mouths
Peak age 30 months (just over 2 years)
Serious harm is uncommon as many household items and medications are of low toxicity and children usually ingest only small amounts

Question 2

Which substances can be potentially fatal

Answer 2

Antihypertensives
Antidepressants
Lamp oil
Button batteries: Can discharge a small electrical current and erode through gastric tissue to cause bleeding and strictures
Magnets: Can clamp together with bowel wall trapped between them, causing ischaemia and perforation → requires urgent surgical referral for >1 magnet

Question 3

What would the signs be for a patient with a deliberate anticholinergic (TCAs, antihistamines) overdose

Answer 3

Raised HR and BP
RR normal
Temperature raised
Pupils dilated
Reduced sweating

Question 4

What would the signs be for a patient with a deliberate opioid overdose

Answer 4

Reduced HR and BP
Reduced RR
Reduced temperature
Constricted pupils
Reduced sweating

Question 5

What would the signs be for a patient with a deliberate sympathomimetic (cocaine, amphetamines) overdose

Answer 5

HR and BP raised
RR raised
Temperature raised
pupils dilated
Sweating increased

Question 6

What would the signs be for a patient with a deliberate sedative-hypnotic (anticonvulsant/benzo) overdose

Answer 6

Reduced HR and BP
Reduced RR
Reduced temp
Pupils normal
Reduced sweating

Question 7

What is the management for a child with poisoning

Answer 7

1. Identify the agent (ask patient, parents, look for clinical signs)
2. Determine toxicity of agent - use ToxBase, report dose, symptoms, time since ingestino
3. Within 1 hour of ingestion → consider reduction of absorption using activated charcoal
4. Investigations
5. Management as according to agent ingested

If low-toxicity + asymptomatic → reassure and discharge ± health visitor for risk assessment and health promotion advice for safe storage

Question 8

What investigations should be done for poisoning

Answer 8

FBC
Renal screen
Liver function
ECG (drug has cardiovascular toxicity)
Specific blood concentrations (paracetamol, iron, salicylates, alcohol)
Urine toxicology screen

Question 9

Paracetamol poisoning: mechanism, symptoms, management

Answer 9

Gastric irritation, saturation of liver metabolism → toxic metabolite NAPQI

Early: abdo pain + vomiting
Late: liver failure (12-24h)

Measure plasma paracetamol
IV N-Acetylcysteine

Question 10

Button battery poisoning: mechanism, symptoms, management

Answer 10

Electrical circuit production from caustic hydroxide → corrosion of gut wall

Abdo pain, gut perforation and stricture formation

CXR/AXR: identify position
In the oesophagus, fails to pass, symptoms present → Endoscopic removal

Question 11

Carbon monoxide poisoning: mechanism, symptoms, management

Answer 11

Binds to Hb → tissue hypoxia

Early: headache, nausea
Late: confusion, drowsiness, coma

High flow oxygen (hasten CO dissociation)

Question 12

Salicylates poisoning: mechanism, symptoms, management

Answer 12

Direct stimulation of the resp. centre
Uncouples oxidative phosphorylation → metabolic acidosis + hypoglycaemia

Early: vomiting, tinnitus
Late: resp. alkalosis → met. acidosis

Measure plasma salicylate concentration 2-4h after ingestion
Alkalinisation of urine (increased salicylate excretion)
Haemodialysis

Question 13

Tricyclic antidepressant poisoning: mechanism, symptoms, management

Answer 13

Anti-cholinergic, interferes with cardiac conduction pathways

Early: tachycardia, drowsiness, dry mouth
Later: arrhythmias, seizures

Arrhythmia →. Sodium bicarbonate
Support breathing

Question 14

Ethylene glycol poisoning: mechanism, symptoms, management

Answer 14

Produces toxic metabolites that interferes with intracellular energy production

Early: intoxication
Later: tachycardia, metabolic acidosis → renal failure

Fomepizole
Haemodialysis

Question 15

Alcohol poisoning: mechanism, symptoms, management

Answer 15

Inhibitory effect on glycolysis in the liver + brain neurotransmission

Hypoglycaemia, coma, respiratory failure

Monitor blood glucose, correct if necessary
Support ventilation

Question 16

Iron poisoning: mechanism, symptoms, management

Answer 16

Local corrosion to gut mucosa + disruption of oxidative phosphorylation in the mitochondria → free radicals, lipid peroxidation, metabolic acidosis

Initial: vomiting, diarrhoea, haematemesis, melaena, acute gastric ulceration
→ latent period of improvement
6-12h later: drowsiness, coma, shock, liver failure + hypoglycaemia, convulsions
Long term: gut strictures

Serum iron level 4 hours after ingestion
IV deferoxamine (iron chelation)

Question 17

Hydrocarbons e.g. paraffin, kerosene poisoning: mechanism, symptoms, management

Answer 17

Facilitates aspiration → lung toxicity
Direct inhibitory effect on neurotransmission in the brain

Supportive treatment

Question 18

Organophosphorus poisoning: mechanism, symptoms, management

Answer 18

Inhibition of acetylcholinesterase → ACh accumulation in the nervous system

Salivation, lacrimation, urination, diarrhoea, vomiting, muscle weakness, cramps and paralysis, bradycardia and hypotension
Seizures and coma

Atropin
Supportive care
Pralidoxime (reactivates acetylcholinesterase)

Question 19

What are the most common causes of chronic environmental poisoning

Answer 19

Lead
Pesticides

Question 20

What are the symptoms of chronic lead exposure

Answer 20

Behavioural changes
Hyperactivity OR decreased activity
Developmental delay or loss of developmental milestones
Chronic lead nephropathy
Abdominal pain, vomiting, constipation
Headache and ataxia
Lethargy, seizures, and coma

Question 21

What is the management for lead environmental poisoning

Answer 21

Chelation therapy to reverse acute symptoms (encephalopathy)

However treatment is complex as lead is deposited in the bone and has a long half life