Calculating PRBC Infusion Rate

During a unit of packed red blood cell (PRBC) transfusion, a nurse is monitoring the patient for any adverse reactions. The healthcare provider has ordered 1 unit of PRBCs to be transfused over 4 hours. As the nurse, calculate the correct infusion rate using the drop factor provided by the manufacturer, which is 15 gtt/mL. The nurse will document the infusion rate in mL/hr. Fill in the blank: The infusion rate of PRBCs should be set at _____ mL/hr.