sentence1: This observation was based in part on the results of a national survey of trauma centers which revealed that blood alcohol testing, which is often a precursor for any intervention, was routinely conducted at only 64 percent of centers despite a published guideline by the Committee on Trauma of the American College of Surgeons indicating that testing was an essential characteristic for those centers.
sentence2: A national survey revealed 100% of centers were conducting the mandatory blood alcohol testing.