Before starting an infusion of arsenic trioxide, which should be ensured by the nurse?

For the administration of arsenic trioxide, ensuring that the serum potassium level is greater than 4 mEq/L is critical. Arsenic trioxide is known to potentially cause electrolyte imbalances, including hypokalemia, which can lead to serious cardiac complications such as arrhythmias. Monitoring potassium levels is vital in preventing such occurrences, as low potassium can exacerbate the risk of QT interval prolongation associated with this medication.

While electrolyte levels are crucial for safe administration, the other options do not align with the primary considerations before starting the infusion. The QTc interval, for instance, should be monitored closely during treatment, but a QTc interval greater than 500 milliseconds would actually indicate a risk for arrhythmias, rather than a safe parameter for infusion. Additionally, the specifics of the infusion duration and baseline pulmonary function tests, while important for other aspects of patient management and safety, are not primary concerns that need to be verified immediately before starting an arsenic trioxide infusion. Therefore, ensuring adequate serum potassium is a key step in safeguarding the patient’s heart health during the treatment process.