Weissman C, et al. - Using retrospective data, researchers examined the link between duration-of-surgery (DOS) and post-anesthesia care unit (PACU) length-of-stay (LOS), the PACU-LOS:DOS ratio, because it is one of the determinants of the number of PACU beds and nurse staffing needed to ensure efficient egress of patients from the operating room (OR). Phase 1 and Phase 2 were involved. Overall 17,047 patients were included in Phase 1, with most of them with PACU-LOS:DOS ratios >1.0, showing PACU-LOS longer compared to DOS. Median PACU-LOS and median DOS were 117 minutes and 80 minutes, respectively. The median PACU-LOS/DOS ratio was estimated to be 1.5. For showing interactions between 2 central components of the surgical system, the utility of the PACU-LOS/DOS ratio was proved in this study. Objective evidence was gained for the number of PACU beds exceeding the number of ORs. This evidence was offered by many patients with PACU-LOS:DOS ratios >1.0.