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- TCAs are weak bases (pKa 8.5) that can cause life-threatening sodium channel toxicity
- Ingestion of 15 mg/kg tricyclic antidepressants would be expected to result in serious, potentially life-threatening
- CVS – dry mucous membranes, tachycardia, hypertension -> hypotension -> cardiovascular collapse (arrhythmia), postural hypotension, dehydration
- CNS – nystagmus, dizziness, agitation, decreases level of consciousness, unconscious/coma, seizures, increase in tone, clonus, tremor, hypereflexia, pupillary dilation, blurred vision
- GI – N+V, abdominal pain, dry mouth, ileus
- METABOLIC – severe metabolic acidosis, fever
- GU – urinary retention
- SKIN – flushed
- ABG – metabolic acidosis
-> sinus tachycardia
-> PR prolongation
-> R wave > 3mm in aVR
-> prolonged QT interval (>430ms)
-> QRS prolongation (>100ms)
-> 2nd or 3rd HB
- Bloods – renal impairmen
- Consider activated charcoal if the patient presents within 1 hour of ingesting a toxic dose. A second dose of charcoal should be considered after 1 – 2 hours in patients with features of toxicity.
- In adults consider immediate administration of 50 – 100 mL of 8.4% sodium bicarbonate
- Wide QRS or arrhythmias
- Metabolic acidosis
- If metabolic acidosis persists despite correction of hypoxia and adequate fluid resuscitation, consider correction with intravenous sodium bicarbonate.
- Agitation: Diazepam
- Convulsions: Benzodiazepines.NB. Avoid phenytoin
- If cardiotoxicity is unresponsive to the above consider the use of a lipid emulsion; 5 mL/kg of 20% Intralipid as an intravenous bolus followed by 0.25 – 0.5 mL/kg/min for 30 – 60 minutes, to an initial maximum of 500 mL.
- All patients should be observed for at least 6 hours after ingestion.