QUESTIONS and CONTROVERSIAL ISSUES

The patient hands you a brown paper bag filled with medication bottles and loose unmarked pills. Her medications include: Lanoxin 0.25; Procardia SR; Lasix m; and K-dur 20meq.

I) What is the toxicologic differential diagnosis of a patient presenting with bradycardia and hypotension?

1. Anticholinesterase drugs
2. Digitalis
3. Beta blockers
4. Opioids Calcium channel blockers, Clonidine

II) Compare and contrast acute versus chronic digitalis toxicity

• A) Acute
  1. Typically younger patient population
  2. Higher levels than chronic yet less symptomatic
  3. Hyperkalemia (action on the Na+/K+ ATPase pump)
  4. Supraventricular heart block, bradyarrythmias, general lack of ventricular arrhythmias
  5. Levels may guide therapeutic intervention
• B) Chronic
  1. Older patients with underlying cardiac disease
  2. Higher morbidity, mortality than acute
  3. Greater target organ toxicity
  4. More potential for drug interactions
  5. Lower clinical index of suspicion, vague symptoms
  6. Normal or hypokalemia (Pt typically on diuretics)
  7. Arrhythmias-all types, mostly tachydysrhythmias
  8. Digitalis levels may not guide management
  9. Similar to other chronic toxicities (Lithium, Theophylline, Salicylates)

III) What are the indications for FAB fragments?

1. Severe ventricular dysrythmias
2. Progressive bradyarrythmias
3. Potassium levels >5.5
4. Acute postingestion levels greater than 10-15ng/ml, (levels less helpful in chronic toxicity)
5. Hemodynamic compromise
6. Concomitant renal failure
7. To confirm diagnosis of suspected digitalis poisoning?

Dosing of Digibind:

1)	Dose(#of vials)=Serum digoxin conc(ng/ml)X Wt(kg)
                    ______________________________
		     	       100

2)	Dose(#of vials)= Total digitalis body load (mg)
                      ____________________________
		  0.6mg of digitalis bound / vial	
	
3)	If amount unknown or levels unavailable: 
			administer 10-20 vials				

IV) Adverse effects of Digibind Hypokalemia

• Worsening CHF
• Increased ventricular rate (rapid a fib)
• Allergic Rx

IV) Is there a role for glucagon and calcium in this case?

• Glucagon: first line antidote in Beta blocker overdose
  1. May also be efficacious in CCB toxicity by increasing cAMP, activating calcium channels.
  2. Dose: 5-10mg IVP
• Calcium gluconate/calcium chloride
  1. First line antidote in CCB overdose
  2. Indicated for hyperkalemia/cardiovasc compromise
  3. CONTRAINDICATED in digitalis toxicity. (Digitalis inhibits Na-K ATPase resulting in increased intracellular sodium and calcium).

  CLINICAL COURSE

  The patient is given 2mg of atropine with little effect. She receives a dose of activated charcoal premixed with sorbitol. The digoxin level returns with a value of 6.3ng/ml. The patient is given 10 vials of digibind FAB fragments with resolution of her hypotension and bradycardia within 30 minutes of administration. Her repeat potassium is 4.2, but repeat digoxin level is 49.0. After a 7 days in a monitored setting, she is cleared by the psychiatry service and discharged home without sequelae.