A nurse in a provider's office is monitoring blood electrolytes for four clients who take digoxin.
Which of the following electrolyte values increases a client's risk for digoxin toxicity?
Potassium 3.0 mEq/L.
Calcium 9.2 mg/dL.
Sodium 140 mEq/L.
Magnesium 2.2 mg/dL.
The Correct Answer is A
This is because low potassium levels (hypokalemia) increase the sensitivity of the heart to digoxin and can lead to toxicity even with normal serum digoxin levels. Digoxin inhibits the sodium-potassium pump on the cardiac cells, which causes potassium to accumulate outside the cells. Low potassium levels in the blood create a larger gradient for potassium to move out of the cells, which enhances the effect of digoxin and can cause arrhythmias.
Choice B is wrong because calcium 9.2 mg/dL is within the normal range (8.5 to 10.2 mg/dL) and does not increase the risk of digoxin toxicity. However, high calcium levels (hypercalcemia) can potentiate the effects of digoxin and cause toxicity.
Choice C is wrong because sodium 140 mEq/L is within the normal range (135 to 145 mEq/L) and does not increase the risk of digoxin toxicity. However, high sodium levels (hypernatremia) can reduce the binding of digoxin to the sodium-potassium pump and decrease its efficacy.
Choice D is wrong because magnesium 2.2 mg/dL is within the normal range (1.7 to 2.4 mg/dL) and does not increase the risk of digoxin toxicity. However, low magnesium levels (hypomagnesemia) can increase the sensitivity of the heart to digoxin and cause toxicity.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
Alpha 1 adrenergic blocking agents have a vasodilating effect and can be used for the management of hypertension. They work by blocking the alpha 1 receptors on the vascular smooth muscle, which normally cause vasoconstriction when stimulated by catecholamines like epinephrine and norepinephrine.By preventing this constriction, alpha 1 blockers lower the peripheral resistance and blood pressure
Choice A is wrong because alpha 3 adrenergic blockers do not exist.There are only two types of alpha receptors: alpha 1 and alpha 2
Choice B is wrong because alpha 2 adrenergic antagonists do not have a vasodilating effect.
They block the alpha 2 receptors, which are located presynaptically on the sympathetic nerve terminals and postsynaptically on some vascular smooth muscle cells.Alpha 2 receptors inhibit the release of norepinephrine when activated, so blocking them would increase the sympathetic activity and vasoconstriction
Choice C is wrong because alpha 1 adrenergic agonists do not have a vasodilating effect.
They stimulate the alpha 1 receptors, which cause vasoconstriction and increase the blood pressure.Alpha 1 agonists are used to treat hypotension and nasal congestion
Correct Answer is C
Explanation
Digibind is the trade name forantidigoxin, which is an antibody made up of anti-digoxin immunoglobulin fragments.It is thespecific antidoteto digoxin toxicity, which can occur even when the serum digoxin concentration is within the therapeutic range.Digoxin toxicity causes anorexia, nausea, vomiting, neurological symptoms and arrhythmias.
Choice A, Protamine sulfate, is wrong because it is the antidote for heparin overdose, not digoxin toxicity.
Protamine sulfate reverses the anticoagulant effect of heparin by binding to it and forming a stable complex.
Choice B, Acetylcysteine, is wrong because it is the antidote for acetaminophen overdose, not digoxin toxicity.
Acetylcysteine replenishes glutathione, which is depleted by acetaminophen metabolites that cause hepatotoxicity.
Choice D, Vitamin K, is wrong because it is the antidote for warfarin overdose, not digoxin toxicity.
Vitamin K restores the synthesis of clotting factors that are inhibited by warfarin.
Normal ranges for serum digoxin concentration are 0.6 to 1.2 nanomol/L (0.5 to 0.9 nanograms/mL) for heart failure and unknown for atrial fibrillation without heart failure.
Normal ranges for serum potassium level are 3.5 to 5.0 mmol/L and for serum magnesium level are 0.7 to 1.0 mmol/L.
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