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 A
Explanation
Digoxin is a medication that can help the heart pump more blood and slow down the heart rate in certain conditions, such as heart failure and atrial fibrillation.However, digoxin has a narrow therapeutic range, which means that too much or too little of it can be harmful.The therapeutic range of digoxin levels in the blood is 0.5-2 ng/mL, and the toxic level is >2.4 ng/mL.Digoxin should be held if the resting apical pulse of an infant is <90 bpm, an older child is <70 bpm, or an adult is <60 bpm.A pulse of 48/min in an adult is too low and could indicate digoxin toxicity, which can cause life-threatening arrhythmias. Therefore, the nurse should withhold the dose and notify the health care provider immediately.
Choice B is wrong because notifying the health care provider and monitoring the patient’s vital signs are not enough.
The nurse should also withhold the dose to prevent further exposure to digoxin.
Choice C is wrong because rechecking the pulse, making sure to count for 1 full minute, is not necessary.The nurse should already have counted the pulse for 1 full minute before administering digoxin, as per standard procedure.
Choice D is wrong because administering the dose could worsen the patient’s condition and increase the risk of digoxin toxicity and arrhythmias.
Correct Answer is B
Explanation
Class IV antidysrhythmics or calcium channel blockers decrease the flow of calcium ions into cardiac and vascular smooth muscle cells, thus decreasing heart rate and contractions.By reducing the calcium influx, they also decrease the slope of phase 0 and 4 and prolong phase 2 of the cardiac action potential.This results in vasodilation, reduced myocardial oxygen demand, and decreased conduction through the AV node.
Choice A is wrong because calcium channel blockers do not increase blood vessel spasm, but rather cause vasodilation.
Choice C is wrong because calcium channel blockers do not decrease refractory period, but rather prolong it by extending phase 2 of the cardiac action potential.
Choice D is wrong because calcium channel blockers do not increase heart rate, but rather decrease it by slowing down the pacemaker activity and AV nodal conduction.
Normal ranges for heart rate are 60 to 100 beats per minute, and for blood pressure are 120/80 mmHg or lower.
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