Which lab value would be most likely to cause the following dysrhythmia?
Ca 12
Mag 3.1
K+ 2.6
Mag 1.1
The Correct Answer is D
A. Hypercalcemia (Calcium > 10.5 mg/dL) can lead to shortened QT intervals, not prolonged ones, and is unlikely to cause Torsades de Pointes.
B. A magnesium level of 3.1 mEq/L is slightly elevated and would not contribute to QT prolongation or Torsades de Pointes. In fact, magnesium supplementation is a treatment for this condition.
C. Hypokalemia (Potassium < 3.5 mEq/L) can prolong the QT interval and contribute to dysrhythmias, but it is less commonly a direct cause of Torsades de Pointes compared to hypomagnesemia. A potassium level of 2.6 mEq/L is low but would not typically result in Torsades without coexisting hypomagnesemia.
D. Hypomagnesemia (Magnesium < 1.5 mEq/L) disrupts the heart's electrical activity, prolonging the QT interval and increasing the risk of polymorphic ventricular tachycardia, like Torsades de Pointes. Magnesium is critical for stabilizing myocardial electrical conduction, and a value of 1.1 mEq/L indicates significant deficiency, consistent with this dysrhythmia.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
A. A small, mobile, rubbery lump is often benign, such as a fibroadenoma.
B. A nontender, fixed breast nodule is concerning for malignancy, and further evaluation is necessary, such as imaging or biopsy.
C. Tender, bilateral nodules are commonly seen in benign conditions like fibrocystic breast changes, especially related to the menstrual cycle.
D. A lump that changes in size before menstruation is also typical of benign conditions like fibrocystic changes.
Correct Answer is ["937.5"]
Explanation
Calculate the fluid volume to be administered in the remaining 16 hours:
Total fluid volume - Fluid administered in the first 8 hours = Remaining fluid volume
30,000 mL - (1875 mL/hr * 8 hr) = 15,000 mL
Calculate the infusion rate for the remaining 16 hours:
Remaining fluid volume / Remaining time = Infusion rate
15,000 mL / 16 hr = 937.5 mL/hr
Therefore, the nurse should infuse the IV fluids at a rate of 937.5 mL/hr after the first 8 hours.
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