1. TCA Poisoning

2. Major effects of TCA antidepressant
1. Sodium channel blockade
2. α1-Adrenoreceptor blockade
3. Inhibition of reuptake of biogenic amines (e.g.. Norepinephrine, serotonin)
4. Muscarinic receptor blockade (anticholinergic effects)
5. Histamine receptor blockade (antihistaminic effects)
6. Potassium efflux blockade
7. Indirect GABA antagonism

3. TCA toxicity should be considered in all patients with decreased level of consciousness (LOC) and prolonged QRS complex.
A dose greater than 10 mg/kg or 1000 mg in an adult should be considered life threatening.

4. ECG

5. ECG after therapy

6. Clinical condition improving?
History or clinical
suspicion of
ingestion
absent
Reassess at 6 hours:
Still no major signs of
poisoning?
Bowel sounds present?
Clinical condition improving?
IV line establishment
Cardiac monitoring
Pulse oximetry
ECG
Immediate and continuous observation No
Psychologic consultation
Discharge
Consider activated charcoal
Major signs of poisoning:
Decreased level of consciousness
Respiratory depression
Hypotension
Dysrhythmias
Conduction block (ORS > 100 msec)
Seizures
Yes
present
Admit

7. Management airway and breathing: when in doubt, intubate.
Ventilatory support to avoid respiratory acidosis is critical.
If ingestion is recent: activated charcoal
Physostigmine is contraindicated in CA overdose.

8. Management Hypotension: isotonic crystalloids.
If the QRS is more than 100 msec or if the patient is acidemic, intravenous (IV) sodium bicarbonate (NaHCO3) should also be administered.
NaHCO3 is administered by IV boluses of I to 2 mEq/kg until hypotension resolves and the QRS narrows to 100 msec or until serum pH increases to 7.55.

9. Management
Afler obtaining the desired endpoint with IV NaHCO3 boluses, isotonic continuous IV infusion is initiated by adding three ampules of NaHCO3(50 mEq/ampule) to 1 L of D5W.
The initial IV infusion is started at a usual maintenance rate for IV fluids.
This initial NaHCO3 infusion rate must often be maintained for at least 4 to 6 hours before the rate can be decreased.
For a hypertonic continuous IV solution. four ampules of NaHCO3 are added to I L of D5W. This is occasionally necessary for refractory hypotension with a prolonged QRS or refractory ventricular dysrhythmias.

10. If the patient's hypotension does not resolve, norepinephrine or dopamine is recommended.
High dosage dopamine (up to 30 µg/kg/min) and norepinephrine (up to 1 µg/kg/min) may be necessary.

11. Tachydysrhytmia
NaHCO3 is the treatment of choice for ventricular tachycardia.
No antiarrhytmia.
Wide-complex tachycardia is not necessarily ventricular tachycardia and can be caused by sinus tachycardia with aberrant conduction

12. Treatment of Neurologic Complications of TCA Poisoning
Coma
Endotrachcal intubation
mechanical ventilation
Supportive care
Seizures
Lorazepam or diazepam
Phenobarbital or continuous intravenous midazolam infusion
Hyperthermia
Cessation of seizures with benzodiazepine and phenobarbital
Neuromuscular blockade with vecuronium during phenobarbital loading
General anesthesia
Evaporativc cooling
Ice water bath