Indications for DigiFab (FDA label = pdf link)
1. Acute ingestion of 10mg or more in previously healthy adults or 4mg in a previously healthy children. Or a level of 10ng/mL or more
2. Chronic ingestion of 6 ng/mL (4 ng/mL in kids)
3. Life-threatening toxicity.
- VT or VF
- Progressive Bradycardia
- 2nd or 3rd AVB not responsive to atropine
- K > 5.5 (6 in kids) with rapidly progressive s/s of Dig Tox. [in Circulation 2010, can give empiric DigiFab in acute Digoxin poisoning if K is >5]
Strategies for administration of Antidigoxin Fab (DigiFab)
1 vial of DigiFab (40mg) = neutralizes 0.5mg of Digoxin
ng/mL is the same as mcg/L
Life-threatening cardiac glycoside toxicity, DigiFab should be given (Class I, LOE B)
- Known dose of digoxin taken, 2 vials of DigiFab = 1mg of Dig
- If chronic dig tox or when dose taken of dig unknown: dig level x weight in kg = number of vials to be given
- Life-threatening highly suspected Dig Tox where level could not be immediately obtained, administer empirically 10 to 20 vials
Adverse Effects of DigiFab:
1. Hypokalemia (due to reactivation of Na-K ATPase)
2. Worsening of CCF (due to withdrawal of inotropic effect of digoxin)
3. Rapid Ventricular response in AF (due to withdrawal of digoxin effect on AV node)
Notes:
- Hyperkalemia is both a marker of severity of Dig Tox and associated with poor prognosis
- After DigiFab administration, Dig level may misleadingly increase as DigiFab binds with Dig (Dig level measures both bound and free Dig) until DigiFab is eliminated from the body (may be several days or weeks if renal impairment). Free Dig is the one toxic
- Dig shifts K from inside to outside cell = hyperkalemia, this may lead to increase urinary excretion of K so that patient has hyperkalemia but a whole body deficit of K. When DigiFab reverses dig tox, K shifts back into cell = rapid decline in K concentration.
- Hypokalemia may occur rapidly and so K must be monitored especially the next few hours and corrected accordingly
Posts
No comments:
Post a Comment