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530 Chapter 15: Overdose, poisoning and addiction
Management before waiting for serum iron levels. Gastrointesti-
Activated charcoal may be considered in conscious pa- nal haemorrhage may require blood replacement and
tientswithin1hourofingestionandconsumptionabove metabolic acidosis should be corrected. Liver and re-
120mg/kg.Patientsmayrequireprotectionoftheairway, nal support may be required.
correction of hypoglycaemia and hypokalaemia, and In absence of symptoms, serum levels are monitored
then any metabolic acidosis with intravenous sodium every 2 hours until levels fall or symptoms develop.
bicarbonate. Symptomatic patients with moderate (3–5 mg/L or
Haemodialysis is used if plasma salicylate level is 700 55–90 µmol/L) or severe (>5 mg/L or 90 µmol/L)
mg/L (5.1 mmol/L), renal or cardiac failure, convulsions poisoning may require treatment with i.v. desferriox-
or if there is severe metabolic acidosis. amine. Patients who have not developed symptoms
by 6 hours following ingestion are unlikely to have
had a significant overdose and do not require further
Iron overdose monitoring.
Within an hour of ingestion of large doses of iron,
Definition
gastric lavage or endoscopic removal of tablets may be
Accidental or deliberate overdose of iron salts.
performed.
Aetiology
Iron poisoning is usually seen in childhood and results Tricyclic antidepressant overdose
from accidental ingestion of iron-containing medica-
Definition
tions such as vitamin preparations mistaken for sweets.
Accidental or deliberate overdose of tricyclic antidepres-
sant drugs.
Clinical features
Iron causes acute necrotising gastritis. Patients may de-
Incidence/prevalence
velop nausea, vomiting, abdominal pain and diarrhoea.
Almost 1.8% of poisoning cases, but 18% of all deaths
In severe poisoning acute upper gastrointestinal bleed-
by poisoning.
ing, convulsions and metabolic acidosis may occur. Late
signs in severe overdose include hypotension, coma, hy-
Pathophysiology
poglycaemia and hepatocellular necrosis.
Tricyclic antidepressants have anticholinergic, alpha-
adrenergic blocking, and adrenergic uptake inhibiting
Investigations properties. They also have a quinidine like effect on the
Aserum iron level (ideally at 4 hours after ingestion) is myocardium. Alcohol and other psychotropic drugs in-
the best laboratory measure of severity. Abdominal X- crease the toxicity.
raymay show radio-opaque tablets present in the stom-
ach or small bowel if taken within 2 hours of ingestion.
Clinical features
Araised neutrophil count and serum glucose suggests
Common features include hot, dry skin, dry mouth,
toxicity. LFTs and blood gas measurements should be
dilated pupils and urinary retention.
performed.
Cardiovascular consequences include sinus tachycar-
dia, vasodilation, hypotension and cardiac arrhyth-
Complications mias.
Gastrointestinal perforation or infarction. Neurological consequences include ataxia, nystagmus
and altered levels of consciousness including coma,
Management hypothermia and respiratory depression. There may
In severe poisoning (unconscious or hypotension) be increased tone, increased deep tendon reflexes and
intravenous fluids and desferrioxamine (a chelating extensor plantar responses. If the patient is comatose,
agent for iron) should be commenced immediately all reflexes may be absent.