Duration of Nil Per Os is causal in hospital length of stay following laparoscopic bariatric surgery

Introduction A recent bariatric surgical study demonstrated an inverse relationship of intraoperative hydration with the incidence of extended hospital length of stay (ehLOS: >1 postoperative hospital day). In that study, a post hoc analysis of the preoperative duration of Nil Per Os (NPO) past midnight revealed a significant dose–response association on the incidence of ehLOS, with the lowest incidence (10–12 %) predicted within the 2–5-h NPO interval. As NPO is associated with a state of compensatory dehydration, the objectives of this study were to prospectively examine the role of decreasing preoperative NPO intervals on the incidence of ehLOS in a similar bariatric surgical population and to establish causality of this association.