Average number of anesthetics still in progress in the early evening increased at least proportionally to the numbers of anesthetizing locations in the morning: A retrospective, long-term longitudinal study at two large hospitals

Abstract

BackgroundAn earlier study examined weekend and holiday cases at many hospitals. Over a decade, treating weekend/holiday caseloads simply as proportional to total caseload resulted in a low error rate of <1 case per day, important when making weekend staffing decisions. In the current study, we examine the comparable issue related to evening staffing for the associations between numbers of anesthetics ongoing in the early evening, 6:00 PM, versus the total numbers of anesthetizing locations, specifically at 9:00 AM. MethodsData from two large teaching hospitals, November 2002 through May 2021 and November 2005 through June 2021, respectively, were retrieved and analyzed. ResultsAt one hospital, over 18.6 studied years, there was a 75% increase in anesthetics ongoing at 9:00 AM; Spearman rank correlation 0.99 (P < .0001). There was positive association with anesthetics ongoing at 6:00 PM; Spearman correlation 0.96 (P < .0001). The ratio of anesthetics at 6:00 PM to 9:00 AM increased over time; Spearman correlation 0.82 (P < .0001). Over the past decade, the simple model of proportional growth had a mean absolute predictive error in cases at 6:00 PM being less than 1 case per workday (mean 0.64 cases per workday, <1 case per workday P = .019). At the second hospital, over 15.6 years, there was a 17% increase in anesthetics ongoing at 9:00 AM; Spearman correlation 0.58 (P = .021). There was positive association between those anesthetic counts at 9:00 AM and those ongoing at 6:00 PM; Spearman correlation 0.85 (P < .0001). The ratio of anesthetics at 6:00 PM to 9:00 AM increased over time; Spearman correlation 0.92 (P < .0001). Over the past decade, the model of proportional growth had a mean absolute predictive error in cases at 6:00 PM that was minimal (mean 0.40 cases per workday, <1 case per workday P = .0001). ConclusionsHospitals should plan that as first case starts are added progressively, workload in the early evening may grow at least proportionally, as found for weekends and holidays. Such knowledge is important for operating room managers to consider when planning staffing, staff scheduling, and managerial decision-support for the end of the workday.