Digoxin toxicity: Difference between revisions
Line 61: | Line 61: | ||
== Treatment == | == Treatment == | ||
Fab | '''Fab Fragment Therapy''' | ||
*Indications | *Indications | ||
**Severe rhythm disturbances refractory to conventional therapy | **Severe rhythm disturbances refractory to conventional therapy | ||
Line 68: | Line 69: | ||
**Pacemaker (may mask cardiac dysrhythmia) | **Pacemaker (may mask cardiac dysrhythmia) | ||
**Consider for: | **Consider for: | ||
*** Dig level > 10 in acute ingestion | ***Dig level > 10 in acute ingestion | ||
*** Dig level > 4 in chronic ingestion | ***Dig level > 4 in chronic ingestion | ||
*** If adult acutely ingests > 10mg | ***If adult acutely ingests > 10mg | ||
*** If child acutely ingests > 4mg | ***If child acutely ingests > 4mg | ||
*How To Use | |||
**'''Neither amount ingested nor digoxin level are known:''' | |||
***Adult dose | |||
****10 vials over 30 minutes | |||
***Peds dose | |||
****5 vials | |||
***Peak effect occurs after 90min, initial response after 20min | |||
****Repeat dose if clinical response is inadequate | |||
**'''Amount ingested is known but digoxin level is unknown''' | |||
**Step 1: Calculate total body load (TBL) | |||
***TBL = dose (in mg) ingested | |||
**Step 2: Calculate number of vials needed | |||
***Number of vials = TBL X 2 (round up to nearest whole number) | |||
**'''Steady state digoxin level is known''' | |||
**Number of vials = (dig level(in ng/mL) X pt wt) / 100 | |||
'''Chronic toxicity without severe signs''' | '''Chronic toxicity without severe signs''' | ||
* Give half the recommended dose | **Give half the recommended dose | ||
** Otherwise may unmask the condition for which the pt is taking digoxin | ***Otherwise may unmask the condition for which the pt is taking digoxin | ||
Fab side-effects | |||
*Allergic reaction | |||
* Allergic reaction | *Withdrawal of dig effect: | ||
* Withdrawal of dig effect: | **CHF, a fib w/ RVR | ||
** CHF | *Hypokalemia | ||
* Hypokalemia | |||
<br/>Activated charcoal | |||
*Only an adjunctive tx; NOT an alternative to fab fragment therapy | *Only an adjunctive tx; NOT an alternative to fab fragment therapy | ||
*Consider only if present within 2 hr of ingestion | *Consider only if present within 2 hr of ingestion | ||
*1g/kg (max 50g) | |||
*Hyperkalemia | |||
**Do not treat! Do not give calcium! | |||
***Once fab is given hyperkalemia will rapidly correct | |||
****Aggressive tx with potassium-lowering agents could cause sig hypokalemia following therapy | |||
*Hypokalemia | *Hypokalemia | ||
** Treat! | **Treat! | ||
*Hypomagnesemia | *Hypomagnesemia | ||
** Treat | **Treat | ||
* Rhythm Disturbance | *Rhythm Disturbance | ||
** Bradycardia (symptomatic) | **Bradycardia (symptomatic) | ||
*** Atropine 0.5mg IV | ***Atropine 0.5mg IV | ||
*** Pacing | ***Pacing | ||
** Tachyarrhythmias | **Tachyarrhythmias | ||
*** K | ***K | ||
*** Mag | ***Mag | ||
*** Lidocaine | ***Lidocaine | ||
*** Phenytoin | ***Phenytoin | ||
*** Cardioversion | ***Cardioversion | ||
== Source == | == Source == |
Revision as of 07:23, 18 March 2011
Background
- Positive inotropic effect
- Inhibits Na-K pump -> incr extracelluar K, incr intracellular Na -> incr intracellular Ca
- Increases vagal tone
- Decreases refractory time; increases automaticity
- Increases risk of dysrhythmias
- Renally cleared
- Hemodialysis does not work
Risk Factors
- Hypokalemia
- Hypovolemia
- Hypoxia
- cardiac ischemia
- renal insufficiency
- Meds
- CCBs, amiodarone
Work-Up
- Dig level
- Normal = 0.8-2 ng/mL
- May have toxicity even with "therapeutic" levels
- Measure serum level at least 6 hours after acute ingestion, immediately for chronic ingestion
- If measure before this may be falsely elevated due to incomplete drug distribution
- Normal = 0.8-2 ng/mL
- Chemistry
- Hyperkalemia level correlates with degree of toxicity
- Hyperkalemia does not cause death; lowering K+ does not reduce mortality
- Hypokalemia increases susceptibility in chronic toxicity
- Hypomagnesemia is common
- Hyperkalemia level correlates with degree of toxicity
- Cr/BUN
- Urine output
- ECG (serial)
Clinical Manifestations
Cardiac
- Any type of dysrhythmia is possible except for rapidly conducted atrial arrhythmias
- Most common:
- PVCs
- Bradycardia
- Digitalis Effect
- T wave changes
- QT interval shortening
- Scooped ST segments with depression in lateral leads
GI
- Nausea/vomiting
- Abdominal pain
Neuro
- Confusion
- Weakness
- Visual disturbances
- yellow halos
- Scotomas
- Delirium
Treatment
Fab Fragment Therapy
- Indications
- Severe rhythm disturbances refractory to conventional therapy
- End-organ dysfunction
- Hyperkalemia >5 after acute overdose
- Pacemaker (may mask cardiac dysrhythmia)
- Consider for:
- Dig level > 10 in acute ingestion
- Dig level > 4 in chronic ingestion
- If adult acutely ingests > 10mg
- If child acutely ingests > 4mg
- How To Use
- Neither amount ingested nor digoxin level are known:
- Adult dose
- 10 vials over 30 minutes
- Peds dose
- 5 vials
- Peak effect occurs after 90min, initial response after 20min
- Repeat dose if clinical response is inadequate
- Adult dose
- Amount ingested is known but digoxin level is unknown
- Step 1: Calculate total body load (TBL)
- TBL = dose (in mg) ingested
- Step 2: Calculate number of vials needed
- Number of vials = TBL X 2 (round up to nearest whole number)
- Steady state digoxin level is known
- Number of vials = (dig level(in ng/mL) X pt wt) / 100
- Neither amount ingested nor digoxin level are known:
Chronic toxicity without severe signs
- Give half the recommended dose
- Otherwise may unmask the condition for which the pt is taking digoxin
- Give half the recommended dose
Fab side-effects
- Allergic reaction
- Withdrawal of dig effect:
- CHF, a fib w/ RVR
- Hypokalemia
Activated charcoal
- Only an adjunctive tx; NOT an alternative to fab fragment therapy
- Consider only if present within 2 hr of ingestion
- 1g/kg (max 50g)
- Hyperkalemia
- Do not treat! Do not give calcium!
- Once fab is given hyperkalemia will rapidly correct
- Aggressive tx with potassium-lowering agents could cause sig hypokalemia following therapy
- Once fab is given hyperkalemia will rapidly correct
- Do not treat! Do not give calcium!
- Hypokalemia
- Treat!
- Hypomagnesemia
- Treat
- Rhythm Disturbance
- Bradycardia (symptomatic)
- Atropine 0.5mg IV
- Pacing
- Tachyarrhythmias
- K
- Mag
- Lidocaine
- Phenytoin
- Cardioversion
- Bradycardia (symptomatic)
Source
Rosen's, UpToDate