Final answer:
The nurse should use normal saline to clean the pressure ulcer, as it is gentle on the wound and promotes healing.
Step-by-step explanation:
The nurse should use normal saline to clean the pressure ulcer. Normal saline is a sterile solution containing 0.9% sodium chloride, similar to the fluid found in the body. It is gentle on the wound, helps to maintain a moist environment, and promotes healing. Other irrigating fluids like povidone iodine, hydrogen peroxide, and sodium hypochlorite can be harsh and may inhibit healing or cause damage to the wound.