Digoxin Toxicity

Last updated 20.09.12

 

 

Definition

-  Toxic levels of Digoxin

 

Features

-  ECG changes DDx toxic from non-toxic

-  Therapeutic levels 1-2.6ng/ml

-  50% mortality with levels > 6ng/ml

 

Risk Factors

-  Hypokalaemia

-  Hypernatraemia

-  Hypomagnesaemia

-  ARF

-  Dehydration

-  Acidosis

-  Drug interactions

 

Assocaited S/S

-  1%+/- pts

-  Anorexia, nausea, vomiting, diarrhoea

-  Blurred vision, xanthopsia (yellow-green halos)

-  Confusion, drowsiness, nightmares, agitation, depression

-  0.1-1% pts

-  Psychosis, delerium, amnesia

-  Short QRS, atrial or ventricular ectopics (PVC)

-  Paroxysmal atrial tachycardia w AV block

-  VT, VF, heart block (bradycardia)

 

Ix

-  Levels do not necessarily correlate with toxicity

-  Digoxin levels

-  To be measured >6hrs after dosing, preferably 12hrs+

-  ECG

-  Non-toxic changes

-  Sinus bradycardia

-  ST depression

-   More global than ischaemic

-   Reverse tick, downward scooping

-  TWI

-  Toxic changes

-  Junctional rhythms

-  PVC, Bigeminy

-  Prolonged PR interval (1o heart block)

-  VT --> VF

-  U&E

-  Hypokalaemia: prediosposes to side effects

-  Hyperkalaemia: caused by toxicity

-  Hypernatraemia: predisposes to side effects

-  Acidosis

-  ARF, CRF: predisposes to side effects

-  Cardiac biomarkers: CK, Trop: AMI

 

Toxic ECG

 

Mx

-  O2 therapy

-  Cardiac monitoring

-  IV access

-  Mx of arythmias

-  Antidigoxin (Digibind)

-  IV over 30min

-  Effect by 30min

-  Indicated if

-  Aryhtmia w haemodynamic instability

-  Altered mental state

-  Hyperkalaemia > 5mEq/L

-  Serum Digoxin > 10ng/ml

-  Ingestion > 10mg

-  Dose (# of vials)

-  Chronic

-   Digoxin level (ng/ml) x weight (kg) / 100

-   Unknown amount give 10 vials

-  Acute

-   Amount ingested (mg) x 0.8 / 0.5

-   Unknown amount give 12 vials

-  Magnesium

-  Temporary antiarythmic

-  2g IV bolus --> 1-2g/hr infusion

-  Mx of hyperkalaemia (Do NOT give Calcium)

 

 

References