HPI:

• 76 y/o F with CHF(HFrEF, on digoxin), Afib, CKD III presents with 1 week weakness and fatigue, diarrhea, and decreased po intake.
• Pt denies fevers/chills, chest pain, palpitations, SOB, n/v, oliguria, dysuria
• +daily etoh use
• ECG: irregular, bradycardic, atrial fibrillation, T wave inversions in anterior-septal leads

 Physical Exam:

Vitals: BP 110/58, HR 50s-60s, Temp 97.9 F (oral), RR 16, SpO2 95% 

• Pt alert and oriented, talkative
• Skin: pale, dry lips and oral mucosa
• Cardio/Respiratory: JVD, irregular rate 50s-60s bpm, with 4/6 systolic murmur, rales b/l, b/l non-pitting LE edema
• GI: soft, nontender, +BS
• MSK: generally moves limbs slowly, 4/5 strength b/l with normal tone
• POCUS ECHO showed decreased EF, RV=LV, with a small pericardial effusion
• DDx: Digoxin toxicity,  Hyperkalemia (digoxin?), hypokalemia (furosemide use), CHF exacerbation, ARF, uremic pericarditis

Workup

• Digoxin level, CBC, BMP, trops, CK, Mag, Phos, TSH, proBNP, PT/INR, VBG
• Pertinent results: 
• Hb 6.5, K: 6.2, Digoxin level: 2.1, Cr: 10.7 (baseline 1.7), BUN 64 

Dx: Digoxin toxicity most likely related to acute renal failure

Management:

• Digibind 250ml bolus
• For hyperkalemia- calcium carbonate, sodium bicarbonate, insulin and D50
• Critical care admission with Nephrology following for AKI

Teaching points: 

• Digitalis toxicity is potentially lethal and Digoxin-binding fragments (Digibind) is indicated when:
• Cardiac arrest or life threatening arrhythmias 
• K>5mM 
• >10mg ingested (adult), >4mg ingested (child)
• >12ng/mL serum level 
• Elimination is 60% renal 
•  “Stone Heart theory”- the theoretical risk of giving calcium in setting of digoxin toxicity calcium may lead to an irreversible non-contractile state, due to impaired diastolic relaxation from calcium-troponin C binding 
• There have been a small number of cases reported with a temporal relationship between admin of calcium with digoxin toxicity that caused mortality
• Most animal models were not able to demonstrate this unless they have severe hypercalcemia to start with
• There have been many reports of calcium given in digoxin toxicity without ill-effects 

Mowry JB, et al. Extracorporeal treatment for digoxin poisoning: systematic review and recommendations from the EXTRIP Workgroup. Clin Toxicol (Phila). 2016 Feb;54(2):103-114.

Kanji S, MacLean RD. Cardiac glycoside toxicity: more than 200 years and counting. Critical care clinics. 28(4):527-35. 2012.