Overdose - TCA

Question 1

List the signs and symptoms of mild TCA toxicity. (8)

Answer 1

1. Drowsiness, confusion
2. Tachycardia
3. Slurred speech
4. Hyperreflexia
5. Ataxia
6. Mild hypertension
7. Dry mucus membranes
8. Respiratory depression

Question 2

List the signs and symptoms of severe TCA toxicity. (9)

What timeframe are these considered within?

Answer 2

Within 6 hours of ingestion:

1. Coma
2. Respiratory depression/hypoventilation
3. Conduction delays
4. PVCs
5. SVT
6. VT
7. Hypotension
8. Seizures
9. ECG changes

Question 3

TCA toxicity can lead to…

Answer 3

Aspiration
Hyperthermia
Rhabdomyolysis
APO

Question 4

What ECG changes are anticipated in TCA OD?

What increased risks do these changes signify?

Answer 4

Prolonged PR, QRS and QT intervals.

• increased risk of seizures if QRS >0.10
• increased risk of ventricular arrhythmias if QRS >0.16

Question 5

How is the QT interval measured?

Answer 5

From the very beginning of the Q wave (first negative deflection) to the end of the T wave.

Question 6

TCA’s can also be prescribed to treat…?

Answer 6

Chronic pain and conditions other than depression.

Question 7

In the circumstance of a possible TCA OD, what are the specific signs of toxicity that indicate a need for treatment?

Answer 7

QRS >0.12
Hypotension
Ventricular arrhythmias

Question 8

In the circumstance of a possible TCA OD, if there are no specific signs of toxicity what is the management?

Answer 8

1. Consider potential for developing toxic signs

2. Tx

Question 9

If signs of TCA toxicity, what is the management?

Answer 9

1. Request MICA

2. Supportive care

Question 10

What is the role of MICA in the setting of TCA OD?

Answer 10

Sodium bicarbonate and ETT.

Question 11

List some medications associated with TCA OD.

Answer 11

Amitriptyline, nortriptyline, dothiepin.

Can be mimicked by other sodium channel blockers.