178 Tox icolog y
SPECIFIC POISONSDiscuss these with the senior ED doctor or a clinical toxicologist:
(i) Decontamination:
(a) do not administer charcoal or attempt to induce vomiting
(b) perform whole bowel irrigation if there are significant
numbers of tablets beyond the pylorus.
(ii) Chelation therapy:
(a) Start a desferrioxamine infusion at 2 mg/kg per h and
increase to a maximum of 15 mg/kg per h in severe cases.
3 Most patients will remain asymptomatic, or develop mild gastrointestinal
symptoms only.
(i) Give i.v. fluids to replace vomiting and diarrhoea losses, provide
supportive care and observe for a minimum of 6 h.
4 Refer all moderate-to-severe cases to the ICU team.Digoxin
DIAGNOSIS
1 Tox ic it y o c c u r s f rom a c ut e ove rdo s e or s e c ond a r y t o lon g-t e r m t he r ap y. Fox g love
and oleander ingestion will also cause acute cardiac glycoside poisoning.
2 Acute digoxin overdose in adults is usually intentional. Clinical manifesta-
tions include:
(i) Nausea and vomiting.
(ii) Hyperkalaemia.
(iii) Bradycardia and ventricular arrhythmias.
3 Chronic digoxin toxicity occurs particularly in the elderly and may be
precipitated by renal impairment, hypokalaemia, hypercalcaemia and drugs
such as amiodarone and quinidine. Clinical manifestations include:
(i) Nausea, vomiting, diarrhoea.
(ii) Sedation, confusion, delirium.
(iii) Visual disturbances, such as yellow haloes (xanthopsia).
(iv) Cardiac automaticity and a wide range of ventricular and
supraventricular arrhythmias.
4 Gain i.v. access and send bloods for U&Es and a serum digoxin level.
(i) Therapeutic range for digoxin is 0.5–2.0 ng/mL.
(ii) Take serum levels early to confirm poisoning, and repeat in 4 h if
acute ingestion is suspected.
(iii) The serum digoxin level is most accurate at 6 h post-ingestion.
5 Perform an ECG:
(i) Any cardiac arrhythmia may be seen in both acute and chronic
ingestions.
(ii) The most common arrhythmias are bradycardia, heart block,
paroxysmal atrial tachycardia, ventricular ectopics and
ventricular tachycardia.