Toxicology 8.9 A) Antiarrhythmics : Digoxin

Front 1

5 Indications for Digoxin Immune Fab

[Digibind] ?

Back 1

1. Cardiac arrest
2. Arrhythmia- life threatening
3. Hyperkalaemia > 5.5
4. Ingested dose > 10mg { child > 4mg}
5. Serum digoxin > 15 nmol/mL

Front 2

Mx of hyperkalaemia in digoxin toxicity?

Back 2

1. Sodium bicarbonate 100mmol
2. Insulin - dextrose

*** Calcium is contraindicated [ in cardiac

glycoside-induced hyperkalaemia] "Stone Heart"

K+ > 5.5 reflects degree of toxicity = 100% mortality untreated

Front 3

Mx of AV block in digoxin toxicity?

Back 3

1. Atropine <= 1.8 mg

*** External pacing rarely effective

Front 4

Mx of ventricular arrhythmias in digoxin

toxicity?

Back 4

1. Lignocaine 1mg/kg over 2 minutes

Front 5

Mx of cardiac arrest in digoxin toxicity?

Back 5

1. DigiFab 20 ampoules

*** Standard ACLS measures futile

Limited success with defibrillation
Continue resuscitation until 30 minutes AFTER Digifab

Front 6

Predictors of potentially lethal acute digoxin

toxicity ? {3}

Back 6

1. Total dose ingested > 10 mg [ 4mg -child]
2. Hyperkalaemia > 5.5 mmol/L

*** 100% mortality without treatment
3. Serum digoxin > 15 nmol/L

Front 7

Mx of hyperkalaemia in digoxin toxicity?

Back 7

1. Sodium bicarbonate
2. insulin-dextrose

** calcium gluconate not used due to potential for worsening cardiotoxicity.

Front 8

Dosing of digibind in digoxin toxicity?

[ With risk factors of dose / arrhythmia /

hyperkalaemia / level ]

Back 8

ACUTE:
- 5 ampoules = haemodynamically stable
- 10 ampoules = unstable patient
- 20 ampoules = cardiac arrest
Then: 5 ampoules every 30 minutes until toxicity reversal
CHRONIC:
- 2 ampoules initially
- 2 ampoules every 30 minutes until toxicity reversal
- 5 ampoules in cardiac arrest

Front 9

What are the end points of treatment of

digoxin toxicity with digibind?

Back 9

1. Return of normal cardiac conduction
2. Resolution of gastrointestinal symptoms

Front 10

Which is incorrect regarding the use of Digibind in digoxin toxicity?
A. it is a life-saving antidote in both acute and chronic toxicity
B. It binds both intravascular and interstitial digoxin
C. Dosing can be calculated based on ingested dose in acute and chronic toxicity
D. In Clinical Practice, Emperic doses are usually used.

Back 10

C. Chronic : dosing based on steady state serum digoxin level.

Front 11

What are the 4 broad categories for ECG changes in digoxin toxicity ?

Back 11

1. Ectopic rhythms

2. Depression of pacemakers

3. Depression of conduction

4. Triggered automaticity

Front 12

List 5 ECG effects of digoxin toxicity.

Back 12

1. AV Block- bradycardia (depressed conduction )

2. Premature ventricular contractions (PVC)

3. Accelerated Junctional rhythm

4. Sino atrial arrest

5. Ventricular arrhythmias

6. Atrial tachycardia

7. Junctional tachycardia