A patient with diabetes mellitus is admitted unresponsive to the emergency room. Initial laboratory findings are serum potassium 2.8 mEq/L, serum sodium 138 mEq/L, serum chloride 90 mEq/L, and blood glucose 628 mg/dl. Cardiac monitoring shows multifocal premature ventricular contractions (PVCs). The nurse understands that the patient's PVCs are most likely caused by
dehydration.
hyperglycemia.
hypoxemia.
hypokalemia.
The Correct Answer is D
A. Dehydration: While dehydration can contribute to electrolyte imbalances and hemoconcentration, it is not the direct cause of PVCs. Dehydration may exacerbate underlying cardiac irritability, but the patient’s laboratory findings indicate a specific electrolyte disturbance that more directly affects myocardial conduction.
B. Hyperglycemia: Elevated blood glucose levels, as seen in this patient, can lead to osmotic diuresis and electrolyte loss. However, hyperglycemia itself does not typically cause ventricular ectopy; the arrhythmias are usually secondary to electrolyte disturbances induced by the hyperglycemic state.
C. Hypoxemia: Hypoxemia can trigger arrhythmias due to impaired oxygen delivery to the myocardium. In this scenario, there is no evidence of low oxygen saturation or respiratory compromise reported, making hypoxemia a less likely cause of the PVCs.
D. Hypokalemia: The patient’s serum potassium is 2.8 mEq/L, which is significantly below the normal range (3.5–5.0 mEq/L). Hypokalemia increases ventricular excitability, prolongs repolarization, and predisposes the myocardium to PVCs and more serious arrhythmias. This electrolyte disturbance explains the observed multifocal PVCs and requires urgent correction.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
Rhythm: Sinus, regular
Rate: 120 b/min
P wave: Present, normal
PR interval: Normal, 0.16 seconds
QRS: Narrow, 0.04 seconds
Rhythm interpretation: Sinus tachycardia
Correct Answer is A
Explanation
A. sinus arrhythmia: Sinus arrhythmia is a normal variation in heart rate that occurs with the respiratory cycle, typically seen as a benign increase in heart rate during inspiration and a decrease during expiration. It does not compromise cardiac output or cause symptoms, so a pacemaker is generally not indicated.
B. post cardiac surgery: After cardiac surgery, patients may develop transient conduction disturbances such as heart block or significant bradyarrhythmias. A pacemaker may be indicated if these conduction abnormalities persist and result in hemodynamic instability, as it helps maintain adequate cardiac output during recovery.
C. third-degree AV block: Third-degree atrioventricular (AV) block represents complete dissociation between atrial and ventricular activity, often leading to severe bradycardia and risk of syncope or sudden cardiac arrest. Permanent pacemaker implantation is a primary treatment to restore ventricular pacing and prevent life-threatening complications.
D. bradyarrhythmias: Symptomatic bradyarrhythmias, including sinus node dysfunction or high-grade AV block, can lead to dizziness, syncope, or heart failure due to insufficient cardiac output. Pacemaker therapy provides electrical stimulation to maintain adequate heart rate and improve symptoms, making it a standard indication.
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