A nurse is assessing a client who has Parkinson's disease.
Which of the following manifestations should the nurse expect?

Choice A rationale

Creatinine (normal range: 0.6-1.2 mg/dL) and Blood Urea Nitrogen (BUN) (normal range: 7-20 mg/dL) are indicators of kidney function. While kidney function is important, valproate is primarily metabolized by the liver, making liver function monitoring more critical than routine renal function assessment for this medication.

Choice B rationale

White blood cell count (normal range: 4,000-11,000 cells/µL) measures components of the immune system. Although some anticonvulsants can affect blood counts, valproate's primary adverse effect profile does not typically involve significant or common alterations in white blood cell count requiring routine monitoring.

Choice C rationale

Red blood cell count (normal range: 4.2-5.4 million cells/µL for women; 4.7-6.1 million cells/µL for men) measures oxygen-carrying capacity. While certain medications can cause anemia, valproate is not commonly associated with significant hematological toxicities involving red blood cells that necessitate routine monitoring.

Choice D rationale

Liver enzymes, such as ALT (normal range: 7-56 U/L) and AST (normal range: 10-40 U/L), are crucial to assess for a client taking valproate. This medication is hepatically metabolized and can cause dose-related transient elevations or, rarely, severe, potentially fatal hepatotoxicity, necessitating regular monitoring of liver function.

Choice A rationale

A ventricular pacemaker is designed to pace the ventricles, not the atria. Therefore, a pacemaker spike appearing before each P wave would indicate atrial pacing, which is not the primary function of a ventricular pacemaker. P waves represent atrial depolarization, and a ventricular pacemaker's stimulus is delivered to the ventricles to initiate a QRS complex.

Choice B rationale

A pacemaker spike appearing after each QRS complex suggests either oversensing, undersensing with competitive rhythms, or a malfunction. The purpose of a pacemaker spike is to *initiate* depolarization, not to follow it. If the spike occurs after the QRS, it indicates that the ventricle has already depolarized, and the spike is not contributing to ventricular contraction.

Choice C rationale

A pacemaker spike appearing with each T wave would be inappropriate and potentially dangerous. The T wave represents ventricular repolarization, a vulnerable period during which an electrical stimulus can induce life-threatening arrhythmias like ventricular fibrillation (R-on-T phenomenon). Pacing should occur before ventricular depolarization, not during repolarization.

Choice D rationale

A ventricular pacemaker functions by delivering an electrical impulse to the ventricle when its intrinsic rate falls below a programmed threshold. This impulse, seen as a pacemaker spike on the ECG, should precede ventricular depolarization, thus initiating a QRS complex. This indicates that the pacemaker is effectively stimulating ventricular contraction at the appropriate time.