Combination of cognitive impairment and pressure ulcers

The nurse on the long-term care unit is concerned about the incidence of pressure ulcers in the facility. He has noted what feels like an increase in pressure ulcers for clients who have cognitive impairment. As he considers how to address this problem, it becomes clear that he must identify not only clients with cognitive impairment but also individuals with a combination of cognitive impairment and pressure ulcers.

He also notes that he would like to identify the clients with cognitive impairment who are most at risk before the pressure ulcers occur.

a. The nurse performs a retrospective chart audit on all current residents presently with cognitive impairment and pressure ulcers. This is known as what type of sampling?