A nurse is preparing to administer 2.5 mL of medication intramuscularly to an adult client.
Which of the following is the safest site for the nurse to use?

- A: A heart rate greater than 60/min indicates that the transcutaneous pacing is effectively maintaining a heart rate within a normal range, which is crucial for adequate cardiac output and systemic perfusion.
- B: While 2+ pedal pulses indicate good peripheral perfusion, they do not directly reflect the effectiveness of transcutaneous pacing in treating complete heart block.
- C: Pacer spikes should appear before the QRS complex to show that the pacing stimulus is being delivered appropriately. Spikes after the QRS complex suggest that the pacing is not capturing the heart effectively.
- D: Distended jugular veins would be more indicative of heart failure or fluid overload and do not directly relate to the effectiveness of pacing therapy.

A. Hypotension occurs because hypermagnesemia causes vasodilation, which lowers blood pressure. Magnesium acts as a smooth muscle relaxant, decreasing vascular resistance and contributing to hypotension. This is a common clinical finding when magnesium levels exceed the normal range.

B. Tachycardia is not expected with hypermagnesemia. Elevated magnesium levels depress the heart's electrical activity, leading to bradycardia (slow heart rate) instead of tachycardia.

C. Muscle cramps are typically associated with hypomagnesemia, which increases neuromuscular excitability. In hypermagnesemia, neuromuscular function is suppressed, leading to muscle weakness rather than cramps.

D. Hyperreflexia is a symptom of hypomagnesemia, not hypermagnesemia. In hypermagnesemia, neuromuscular activity is depressed, resulting in diminished or absent deep tendon reflexes