Yellow-Green Halos: Digoxin Toxicity With Three Precipitants
You are the RN admitting a 79-year-old woman with heart failure (EF 30%) and atrial fibrillation for 2 days of nausea, vomiting, and increasing confusion. Home medications are digoxin 0.25 mg PO daily, furosemide 40 mg PO twice daily, lisinopril 10 mg daily, and carvedilol 3.125 mg twice daily. Admission data: HR 46 and irregular, BP 104/62, K 3.1 mEq/L, Mg 1.4 mg/dL, creatinine 1.6 mg/dL (baseline 1.3), digoxin level 2.6 ng/mL drawn 10 hours after her last dose. She reports "yellow-green halos" around the ceiling lights and has vomited twice since arrival. Urine output is 20 mL/hr. Orders: digoxin 0.25 mg PO daily, furosemide 40 mg IV twice daily, KCl 40 mEq PO now, lisinopril 10 mg daily, carvedilol 3.125 mg twice daily, docusate 100 mg daily.
1. Separate the findings into toxicity manifestations versus precipitating factors, and state your first three actions.
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Toxicity manifestations:
- Digoxin level 2.6 ng/mL (therapeutic 0.5–2.0; for heart failure the target is 0.5–0.9, so this is high on both counts)
- Bradycardia - HR 46, irregular
- GI: nausea, vomiting, anorexia
- Visual: yellow-green halos, blurred vision (classic)
- CNS: confusion
Precipitating factors - three of them, and all are on her medication list:
- Hypokalemia (K 3.1) from furosemide - low potassium enhances digoxin binding and precipitates dysrhythmias.
- Hypomagnesemia (Mg 1.4) - low magnesium makes hypokalemia refractory and is independently arrhythmogenic.
- Rising creatinine (1.3 → 1.6) - reduced renal clearance of digoxin plus age and low body mass.
First actions:
- Hold digoxin and place her on continuous cardiac monitoring with a 12-lead ECG - the next complication is a bradyarrhythmia or heart block.
- Obtain IV access and notify the provider with the full picture.
- Replete potassium and magnesium per order/protocol, and recheck renal function. Keep potassium in the 4.0–5.0 range for a patient on digoxin.
Prepare for digoxin immune Fab (level, weight, renal function) if she develops a life-threatening dysrhythmia, symptomatic bradycardia unresponsive to atropine, or hyperkalemia - but do not administer it without an order.
2. At 09:00 which ordered medications do you give, which do you hold, and what is the reasoning for each?
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| Order | Action | Reasoning |
|---|---|---|
| Digoxin 0.25 mg | Hold | Level is toxic, HR 46; giving another dose deepens the toxicity. Also notify the provider that 0.25 mg is a high maintenance dose for a 79-year-old with reduced renal function. |
| Furosemide 40 mg IV BID | Hold and clarify | It is the direct cause of her hypokalemia; continuing it during repletion will keep her potassium falling. The provider may reduce the dose or switch strategy. |
| KCl 40 mEq PO | Give | K 3.1 with a toxic digoxin level is the highest-yield correction available to you. Give with food; watch for phlebitis if the route changes to IV (never push undiluted). |
| Lisinopril 10 mg | Hold and notify | Creatinine has risen 0.3 mg/dL - an acute kidney injury signal; ACE inhibitors can worsen renal function in this setting. |
| Carvedilol 3.125 mg | Hold and notify | HR 46 - a beta-blocker blunts the compensatory rate and worsens bradycardia. |
| Docusate 100 mg | Give | Not implicated; constipation and straining are a risk in a patient with heart failure. |
The pattern to articulate: three of her six medications either cause or worsen the toxicity, and one of them is the antidote to the problem. That is why this is not a "just hold the digoxin" question.
3. What will you monitor to know the plan is working, and what must the next nurse know at handoff?
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Monitoring:
- Continuous cardiac rhythm and HR; repeat ECG after potassium is replaced - hypokalemia correction can unmask or resolve dysrhythmias.
- Recheck K, Mg, and creatinine after repletion, and again per protocol; the potassium will not hold if the magnesium stays at 1.4.
- Urine output (currently 20 mL/hr) as a marker of renal recovery and drug clearance.
- Trend of GI symptoms, confusion, and visual disturbance - these track the level down.
- If another level is drawn, ensure it is at least 6–8 hours after a dose so it reflects tissue distribution; a level drawn too early reads falsely high.
Handoff must include:
- Digoxin, furosemide, lisinopril, and carvedilol are held and the provider has been notified - with the time, name, and response.
- The three precipitating factors (K, Mg, creatinine) and when the next labs are due.
- The observation-level directive: no digoxin until the level and rhythm are reviewed, and call for HR <50 or any new dysrhythmia.
- Discharge risk: this patient lives on a combination that produced toxicity. Before she goes home, the dose, the potassium monitoring plan, and the early-warning symptoms (nausea, visual changes, palpitations) need to be taught with teach-back - and the family should know to call before the next dose if any appear.