Final answer:
The nurse should first place the hyperkalemic patient on a cardiac monitor to assess heart rhythm and address any life-threatening cardiac arrhythmias before proceeding with other treatments.
Step-by-step explanation:
When caring for a dehydrated patient with acute kidney injury (AKI) who is oliguric (producing little urine), anemic, and hyperkalemic (having an elevated potassium level), the nurse should prioritize interventions based on urgency and potential risks. The most immediate life-threatening issue in this scenario is hyperkalemia, as it can cause fatal cardiac arrhythmias. Therefore, the nurse should first place the patient on a cardiac monitor to continuously assess the patient's heart rhythm and initiate treatment accordingly. This is imperative before interventions such as inserting a urinary retention catheter, administering epoetin alfa (to address anemia), or giving sodium polystyrene sulfonate (Kayexalate to treat hyperkalemia) are considered.