Overdose: TCA Antidepressants (Adult)


Status
Suspected TCA overdose (see also list)

Assess
• Substance involved • Perfusion status • ECG criteria

Are there any of the following:
• Less than adequate perfusion • QRS >0.12 sec. (>0.16 sec. indicates severe toxicity) • QT prolongation (>1/2 R-R interval)

	No
No toxicity
BLS
Consider potential to develop signs of toxicity

Yes
Signs of TCA toxicity
Sodium Bicarbonate 8.4% 100ml IV, given over 3 minutes - Repeat Sodium Bicarbonate 8.4% 100ml IV, after 10 minutes if signs of toxicity persist - Severe cases may require continuing doses - Consult
Consider Intubation if signs of toxicity and GCS <10 persist after initial Mx - Hyperventilate with 100% O2 - Rate 20-24bpm - EtCO2 target 20-25mmHg if intubated

Special Notes

Signs and Symptoms of TCA Toxicity

• Mild to moderate OD
- Drowsiness, confusion
- Tachycardia
- Slurred speech
- Hyperreflexia
- Ataxia
- Mild hypertension
- Dry mucus membranes
- Respiratory depression

• Severe toxicity (within 6hr. ingestion)
- Coma
- Respiratory depression/hypoventilation
- Conduction delays
- Premature Ventricular Contractions (PVCs)
- SVT
- VT
- Hypotension
- Seizures
- ECG changes

This could lead to aspiration, hyperthermia, rhabdomyolysis and acute pulmonary oedema.

ECG changes
ECG changes include prolonged PR, QRS and QT intervals associated with an increased risk of seizures if QRS >0.10 sec. and ventricular arrhythmias if QRS >0.16 sec.

How to measure a QT interval is shown below.

Endotracheal Intubation