When is sodium bicarbonate indicated in the management of tricyclic antidepressant overdose?

Sodium bicarbonate is indicated in the management of tricyclic antidepressant overdose primarily when there are signs of severe metabolic acidosis. This is because tricyclic antidepressants can cause significant cardiotoxicity, including arrhythmias, due to their effects on sodium channels and their ability to cause metabolic acidosis. When metabolic acidosis is present, administration of sodium bicarbonate can help to buffer the acid in the blood, raising the blood pH and potentially improving cardiac function by reversing the cardiotoxic effects associated with the overdose.

Moreover, administering sodium bicarbonate can also help to improve urinary excretion of tricyclic antidepressants through alkalinization of the urine, further aiding in the removal of the drug from the system. The presence of severe metabolic acidosis is a critical factor that necessitates the use of sodium bicarbonate, as it indicates a more serious need for intervention to correct the acid-base imbalance and address potential life-threatening complications.