The ratio of PACU length-of-stay to surgical duration: Practical observations

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.

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).

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.

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.