The nurse observes the following EKG. Which lab would the nurse correlate with this finding?
Na + 134
K+ 6.1
K+ 2.1
Mg+ 18
The Correct Answer is C
A. Mild hyponatremia (Sodium < 135 mEq/L) typically does not produce distinctive ECG changes. This value is unlikely to correlate with the presence of U waves.
B. Hyperkalemia (Potassium > 5.0 mEq/L) is associated with peaked T waves, widened QRS complexes, and flattened or absent P waves, not U waves.
C. Hypokalemia (Potassium < 3.5 mEq/L) is the primary cause of U waves. A potassium level of 2.1 mEq/L is significantly low and can result in ECG changes, including U waves, ST segment depression, and prolonged QT intervals. These changes reflect altered ventricular repolarization.
D. Hypermagnesemia (Magnesium > 2.5 mEq/L) can cause ECG changes such as prolonged PR and QRS intervals, bradycardia, and heart block. However, such an extreme magnesium level of 18 mEq/L would cause severe toxicity and is not associated with U waves.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
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.
Correct Answer is B
Explanation
A. Adenosine 6 mg IV push: Adenosine is used for certain supraventricular tachycardias, but immediate cardioversion is the first priority for a client with atrial flutter and chest pain.
B. Immediate cardioversion: This is the correct answer. Immediate cardioversion is indicated for atrial flutter with signs of hemodynamic instability, such as chest pain and shortness of breath.
C. Adenosine 12 mg IV push: Adenosine may be used after the first dose of 6 mg if the initial dose was ineffective, but cardioversion takes precedence for unstable patients.
D. Amiodarone 150 mg bolus followed by a 24-hour drip: Amiodarone is an antiarrhythmic used for rate control or rhythm conversion but is not the first step for hemodynamically unstable clients with atrial flutter.
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