TCA OVERDOSE

Remember the actions of TCAs:

• SNRI
• Anticholinergic: All D's (Dry Mouth, Dry skin and hyperthermia, DIlated pupils, Depressin of Respiration, Disorder Heart Rhythm,  Delayed Gastric Emptying, Distended Bladder) and Agitation (Remember the atropine psychosis in OPC Poisoning)
• Alpha 1 Blocker: Hypotension
• Na+ Channel Blocker: Wide PR, QRS, QT

Fatal Dose: 15 mg/kg

Management:

Approach in ABCDE Method:

Airway: Nasal Oxygen

Breathing: Assisted Ventilation

Circulation: IV Access (Lab workup: Venous blood Gas for Acidosis, FBC, U & Es, Renal Functions, Acetaminophen levels), EKG, Vitals, Monitoring, 

IV Fluids

Antidotes:

If taken within 2 hours: Give Oral Charcoal 50 gms

Correct Acidosis: With NaHCO3

50 ml of 8.4% over 15 minutes, then 500 ml of 1.8% over 4 hours (Give HCO3, even if pH is normal, try to keep pH > 7.5, if QRS > 100, monitor hypokalemia)

IV benzodiazepines for convulsions (Avoid phenytoin -- Na+ Channel blocker)

Treat Arrythmia with fluids and NaHCO3, avoid Antiarrythmic Class 1a and 1c -- Na+ Channel Blockers

HD if required,

Refer TOXBASE

Refer ITU

Pearls:

• Metabolic acidosis is poor prognostic indicator
• EKG assessment of QRS duration, R wave in aVr > 3 mm
• Give Charcoal if within 2 hours (TCA delays gastric emptying)
• NaHCO3 to be given until pH > 7.5
• Check potassium when using HCO3
• Prolonged CPR in arrest state