The nurse is caring for a patient on bedrest. The nurse is contributing to the plan of care based on the understanding that pressure ulcers occur at sites of ischemia, which can begin to develop in...

The nurse is caring for a patient on bedrest. The nurse is contributing to the plan of care based on the understanding that pressure ulcers occur at sites of ischemia, which can begin to develop in which of the following time frames?

a. 5 to 10 minutes

b. 20 to 40 minutes