“I Took A Lot of Pills”

HISTORY:
The patient is 68 year old female with a history of CHF, HTN and atrial fib who presents with a chief complaint of feeling “weak and dizzy” after ingesting a handful of her “heart pills” 3 hours prior.

PHYSICAL EXAM
General: Patient appears her stated age, with blue-tinted hair, resting quietly on a monitored bed.
Vitals: P=48 BP= 90/60 RR= 24 T= 98.6
Neck: No JVD
Lungs: Crackles at bases bilat
CV: Bradycardic, Irreg RR, no murmurs
Ext: No cyanosis, thready periph pulses
DIAGNOSTIC STUDIES
ECG: Rate of 40-50/min with 3:1 A-V block
CXR: Cardiomegaly, no acute failure
Lytes: Na=145 K=5.9 Cl=104 HCO3=24
BUN/Cr: 46/2.2
Glucose: 120

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?
Anticholinesterase drugs Aricept,Namenda
Digitalis
Beta blockers
Opioids Calcium channel blockers, Clonidine

II) Compare and contrast acute versus chronic digitalis toxicity

A) Acute
Typically younger patient population
Higher levels than chronic yet less symptomatic
Hyperkalemia (action on the Na+/K+ ATPase pump)
Supraventricular heart block, bradyarrythmias, general lack of ventricular arrhythmias
Levels may guide therapeutic intervention

B) Chronic
Older patients with underlying cardiac disease
Higher morbidity, mortality than acute
Greater target organ toxicity
More potential for drug interactions
Lower clinical index of suspicion, vague symptoms
Normal or hypokalemia (Pt typically on diuretics)
Arrhythmias-all types, mostly tachydysrhythmias
Digitalis levels may not guide management
Similar to other chronic toxicities (Lithium, Theophylline, Salicylates)

III) What are the indications for FAB fragments?
Severe ventricular dysrythmias
Progressive bradyarrythmias
Potassium levels >5.5
Acute postingestion levels greater than 10-15ng/ml, (levels less helpful in chronic toxicity)
Hemodynamic compromise
Concomitant renal failure
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
May also be efficacious in CCB toxicity by increasing cAMP, activating calcium channels.
Dose: 5-10mg IVP
Calcium gluconate/calcium chloride
First line antidote in CCB overdose
Indicated for hyperkalemia/cardiovasc compromise
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.