Relationship between time in the operating room and incident pressure ulcers: a matched case-control study.

The objective was to determine the relationship between time in the operating room (OR) and hospital-acquired pressure ulcers (HAPUs), controlling for temporality. The research team identified 931 HAPUs among surgical patients and matched them to 4 controls by hospital length of stay at the time the pressure ulcer (PU) was documented. A regression model estimated the relationship between OR time and HAPU after controlling for matching, age, sex, admission and current Braden score, weight, year, and American Society of Anesthesiologists physical status score. OR time in the 24 hours prior to PU documentation was associated with PUs. Only 5% of HAPUs occurred within 24 hours of extended (>4 hours) surgery and 58% occurred after hospital day 5. Extended surgery is confirmed as a risk factor for PU development. Most PUs do not appear in the immediate postoperative period, and prevention efforts should focus on postoperative patient care, when most HAPUs develop.