Circulation
Treatment for hypotension
For hypotension due to TCA poisoning, first-line treatment is intravenous fluid resuscitation. If hypotension persists, start inotropic support with noradrenaline (norepinephrine) (see Noradrenaline (norepinephrine) intravenous infusion instructions for advice on preparation and administration of noradrenaline).
Treatment for QRS widening and sodium channel blockade: serum alkalinisation
Commence continuous ECG monitoring and assess serial 12-lead ECGs to detect QRS widening in all except minor TCA poisonings. If the patient has an altered conscious state, perform 12-lead ECGs every 2 hours for at least the first 6 hours.
If QRS widening is progressive and associated with airway, breathing or circulatory compromise (eg arrhythmias, hypotension), or CNS depression, immediately start serum alkalinisation (intravenous sodium bicarbonate) and concurrent hyperventilation therapy (by intubation and mechanical ventilation).
For serum alkalinisation, in adults and children, use:
sodium bicarbonate 8.4% 1 to 2 mL/kg up to 100 mL (1 to 2 mmol/kg up to 100 mmol) intravenously, every 3 to 5 minutes, titrated to a narrowing of the QRS complex and aiming for a serum pH between 7.45 and 7.55. Maximum total dose is 6 mL/kg (6 mmol/kg). Urgently seek advice from a clinical toxicologist if there is inadequate response to the maximum total dose tricyclic antidepressant poisoning - QRS widening
PLUS
hyperventilation by intubation and mechanical ventilation, aiming for a serum pH between 7.45 and 7.55 (typically by maintaining partial pressure of arterial carbon dioxide [PaCO2] between 30 and 35 mmHg).
Serum alkalinisation can cause hypokalaemia due to intracellular potassium shift—monitor the serum potassium concentration and replace potassium if required, aiming for the normal serum potassium concentration.
For more information on the management of QRS widening due to drug poisoning, see Treatment for QRS widening and sodium channel blockade: serum alkalinisation).
If there is inadequate response to serum alkalinisation, urgently seek advice from a clinical toxicologist.
Treatment for other arrhythmias
Commence continuous ECG monitoring and serial 12-lead ECGs in all except minor TCA poisonings. If the patient has an altered conscious state, perform 12-lead ECGs every 2 hours for at least the first 6 hours.
Sodium bicarbonate is the antiarrhythmic drug of choice in patients with TCA poisoning; the same regimen is recommended as for the management of QRS widening and sodium channel blockade. Discuss the treatment of refractory arrhythmias with a clinical toxicologist.
For cardiorespiratory arrest and life-threatening arrhythmias, follow advanced life support protocols1 and seek advice from a clinical toxicologist.
Class 1A antiarrhythmic drugs (eg quinidine, procainamide) are contraindicated in patients with TCA poisoning.