Today I located some wonderful references. First of all, a 2008 paper by Amit Gefen, PhD, finds that a pressure ulcer can be initiated in as short a time as one hour. This provides support to the essential element of the NDF Prevention Protocol that the at-risk patient must be placed on a pressure reducing surface immediately.
The Institute for Healthcare Improvement (IHI.org) under their Programs section has a listing of hospitals that have made significant reductions in hospital-caused PU incidence, and that are willing to serve as mentors to other hospitals. All of them list new support surfaces as an essential element. I plan to ask each which support surface they procured.