After-hour Versus Daytime Shifts in Non-Operating Room Anesthesia Environments: National Distribution of Case Volume, Patient Characteristics, and Procedures.

The objective of this study was to characterize workload during all hours of the day in the non-operating room anesthesia (NORA) environment and identify what type of patients and procedures were more likely to occur during after-hours. By investigating data from the National Anesthesia Clinical Outcomes Registry, we characterized the total number of ongoing NORA cases per hour of the day (0 - 23 h). Results were presented as the mean hour and standard error (SE). Multivariable logistic regression was applied to assess the association of various patient, procedural, and facility characteristics with time of day (after-hours = 17:01-06:59 local time versus day-time). Included in this analysis, there were a total of 4,948,634 cases performed on non-holiday weekdays. The mean hour for ongoing cases for gastroenterology, cardiac, radiology and "other" were: 10.8 with standard error (SE) of 0.002, 11.5 (SE of 0.005), 11.2 (SE of 0.005), and 10.8 (SE of 0.002), respectively. Pairwise differences between means for each NORA specialty were all statistically significant (p < 0.0001). During after-hour shifts (4.3% of cases), patients with higher American Society of Anesthesiologists physical status classification scores had increased odds for undergoing a NORA procedure, while procedures that were more physiologically complex had decreased odds. With the increasing demand for NORA services, it is prudent that we fully understand the challenges of providing safe and efficient anesthetic services particularly in locations where fewer resources are available.