Background Operating room (OR) and post‐anesthesia care unit (PACU) activity are closely linked since the number, type, and sequence of surgeries influence subsequent PACU activity. We aimed to explore the relationship between duration‐of‐surgery (DOS) and PACU length‐of‐stay (LOS), the PACU‐LOS:DOS ratio, since it is among the determinants of the number of PACU beds and nurse staffing required to insure efficient egress of patients from the OR. Methods PACU‐LOS:DOS ratio was examined using retrospective data from a tertiary medical center's surgical information system (Phase 1) and prospectively collected data from a convenience sample of post‐operative patients (Phase 2). Results Phase 1 included 17 047 patients, the majority (73%) with PACU‐LOS:DOS ratios >1.0, indicating PACU‐LOS longer than DOS. Median PACU‐LOS was 117 minutes, median DOS was 80 minutes, and median PACU‐LOS/DOS ratio was 1.5. PACU‐LOS showed greater variability than DOS because of extended PACU stays. Phase 2 ( n = 2054) confirmed Phase 1 results (median PACU‐LOS/DOS ratio ‐ 1.8). In both phases at a DOS of >130 minutes PACU‐LOS/DOS ratio became <1.0. In 24% of Phase 2 patients PACU‐LOS was prolonged because of administrative issues. Post‐operative, more than pre‐ and intra‐operative, measurements influenced PACU‐LOS. Conclusions The PACU‐LOS/DOS ratio proved useful for demonstrating interactions between 2 central components of the surgical system. The many patients with PACU‐LOS:DOS ratios >1.0 provides objective evidence for the number of PACU beds exceeding the number of ORs.
