Your client with end-stage renal disease is receiving 2 unit…

Your client with end-stage renal disease is receiving 2 units of packed red blood cells for anemia (Hgb of 8.2 g/dL [82 g/L)). Twenty minutes into the first transfusion, the nurse observes the client has a flushed face, hives over upper body trunk, and is reporting pain in lower back. His vital signs include pulse rate of 110 and BP drop to 95/56. What is the clinician’s priority action?