Digoxin toxicity

Overview-Incidence

About 1.1% of outpatients on digoxin develop toxicity each year. About 10% to 20% of nursing home residents annually experience some degree of digoxin-related toxicity.

Overview-Pathophysiology

Digoxin inhibits the sodium-potassium pump in myocytes, which results in an increase in intracellular sodium and a decrease in the transmembrane sodium gradient. The loss of the sodium gradient decreases the drive of the Na+-Ca2+ transporter, leading to increased intracellular calcium and increased muscle contractions.

Treatment-Medications

Digoxin-specific Fab antibody fragments (Digibind) Activated charcoal Magnesium

Treatment-General

Discontinuation of digoxin and other medications that interact with digoxin or exacerbate arrhythmias Correction of electrolyte imbalances Treatment of the underlying cause

Nursing Considerations-Associated Nursing Procedures

12-lead electrocardiogram (ECG) Blood pressure assessment Cardiac monitoring IV bag preparation IV catheter insertion Oxygen administration Pulse assessment Pulse oximetry Respiration assessment Venipuncture

Overview-Risk Factors

Advanced age Renal failure Hypoxemia Electrolyte imbalances (hypokalemia, hypomagnesemia, hypernatremia, hypercalcemia) Acid-base disturbances Decompensating heart failure Myocardial infarction Myocarditis Hypothyroidism Cor pulmonale

Assessment-Physical Findings

Anorexia Nausea and vomiting Diarrhea Visual disturbances (yellow halos) Mydriasis Confusion Fatigue Restlessness Weakness Headache Depression Hallucination Neuralgias Vertigo

Treatment-Activity

As tolerated

Overview-Complications

Cardiac arrhythmias Heart failure Hypokalemia

Nursing Considerations-Nursing Diagnoses

Decreased cardiac output Deficient knowledge: Disease process Risk for decreased cardiac perfusion Risk for poisoning

Diagnostic Test Results-Diagnostic Procedures

Electrocardiogram(ECG) tracing will show characteristic "digitalis effect," which can occur at therapeutic levels, and includes: prolonged PR segment T wave changes prolonged T wave intervals, scooping of the ST segment. prolonged PR segment T wave changes prolonged T wave intervals, scooping of the ST segment. Other ECG changes that are relatively specific to digoxin toxicity include: accelerated junctional rhythm bidirectional ventricular tachycardia new-onset Mobitz type I atrioventricular (AV) block nonparoxysmal atrial tachycardia with AV block. accelerated junctional rhythm bidirectional ventricular tachycardia new-onset Mobitz type I atrioventricular (AV) block nonparoxysmal atrial tachycardia with AV block. Other associated ECG rhythms include: ventricular ectopy, premature ventricular contractions high-degree heart block sinus bradycardia sinus bradycardia with junctional tachycardia ventricular fibrillation or tachycardia atrial flutter. ventricular ectopy, premature ventricular contractions high-degree heart block sinus bradycardia sinus bradycardia with junctional tachycardia ventricular fibrillation or tachycardia atrial flutter.

Nursing Considerations-Nursing Interventions

Give prescribed drugs. Help the patient identify and eliminate predisposing factors. Institute continuous cardiac monitoring to evaluate for changes and development of arrhythmias. Establish and maintain a patent airway. Provide oxygen and pulse oximetry, as needed. Initiate and maintain I.V. access, as ordered. If overdose was intentional, arrange for counseling and institute a no-self-harm contract. Obtain specimens for laboratory testing, such as digoxin, sodium, potassium, and electrolyte levels.

Overview

Life-threatening condition that results from intoxication with digoxin from use in long-term therapy, accidental or intentional overdose, or ingestion of naturally occurring compounds containing cardiac glycosides (such as foxglove, oleander, and lily-of-the valley) Possibly acute or chronic

Overview-Causes

Long-term therapy Intentional overdose (suicide) Accidental overdose (children) Prescription or administration error Electrolyte disturbances Renal failure or any condition that decreases clearance of the drug Poisoning with plants containing cardiac glycosides (such as foxglove, oleander, and lily-of-the-valley) Concurrent use of such medications as: antibiotics (rifampin, tetracycline, macrolides) selective serotonin reuptake inhibitors (citalopram, fluoxetine, sertraline, venlafaxine) calcium channel blockers (diltiazem, verapamil) antiarrhythmics (quinidine, amiodarone) diuretics (spironolactone) beta-adrenergic blockers (atenolol, carvedilol, labetalol, metoprolol, sotalol) antibiotics (rifampin, tetracycline, macrolides) selective serotonin reuptake inhibitors (citalopram, fluoxetine, sertraline, venlafaxine) calcium channel blockers (diltiazem, verapamil) antiarrhythmics (quinidine, amiodarone) diuretics (spironolactone) beta-adrenergic blockers (atenolol, carvedilol, labetalol, metoprolol, sotalol)

Assessment-History

Presence of one or more predisposing factors

Patient Teaching-Discharge Planning

Refer the patient for professional counseling or mental health care, as appropriate, if overdose was intentional.

Diagnostic Test Results-Laboratory

Serum digoxin level (with a therapeutic range in serum at 0.8 ng/mL to 2.0 ng/mL for rate control in atrial fibrillation) will show toxic levels at above 2.5 ng/mL. Toxicity may occur with plasma digoxin levels within therapeutic range, especially in chronic overdose.

Treatment-Surgery

Temporary pacing if no Digibind is available Insertion of vascular access for hemodialysis to treat hypokalemia, although not effective for reversal of toxicity because of the extensive tissue distribution of digoxin

Nursing Considerations-Monitoring

Vital signs Cardiopulmonary status Hemodynamics Oxygenation Coping strategies Suicidal ideation Diagnostic test results I.V. access

Treatment-Diet

Well-balanced diet

Patient Teaching-General

disorder and treatment medications prescribed and potential adverse reactions, including redness and drying of skin with topical agents signs and symptoms that require notifying the practitioner.

Nursing Considerations-Expected Outcomes

maintain an adequate cardiac output and hemodynamic stability seek information about the disease process verbalize an understanding of proper administration and use of medicines remain free from complications of decreased cardiac tissue perfusion not experience poisoning related to drugs or chemicals.