Background: We analyze data from the American Society of Anesthesiologist's (ASA) Anesthesia Quality Institute (AQI) to report the U.S. anesthesia workload by time of day and day of the week. We consider the extent to which first case starts, rather than durations of workdays and weekend cases, influence the number of anesthesia providers nationally.
Methods: The ASA AQI data were from all the U.S. anesthesia groups that submitted cases to the National Anesthesia Clinical Outcomes Registry (NACOR) for all 12 months of 2013. For each of the n = 2,075,188 cases, we identified the local date and time of the start of anesthesia care, duration of anesthesia care, and the local time zone. Anesthesia workload was measured as the time from the start to the end of continuous anesthesia care. Data are reported as mean ± SEM with 95% confidence intervals (CIs).
Results: Half (53.0% ± 0.6%) of the ASA AQI-reported weekly anesthesia workload was completed by 1:00 PM, local time, on regular workdays. The busiest 8-hour interval was from 7:30 AM to 3:30 PM and accounted for 70.3% ± 0.7% of anesthetic minutes. Although most facilities completed the majority of their weekly anesthesia workload in the mornings of regular workdays (P < 0.0001; 62.3%; CI, 58.6%-66.1%), just 24.4% of the University and large community hospitals did so (P = 0.0008 relative to half; CI, 13.8%-38.4%).
Conclusions: The results are inconsistent with widespread use of surgical facilities (i.e., anesthesia providers) in mornings only, especially at University and large community hospitals. The observed national work hours match with what would be expected if most anesthesiologists work at least 8 hours on regular workdays. Opportunity for greater use of the capital (building and equipment) probably would involve the use of additional anesthesia providers representing a second shift or use of weekends.