Effect of the elective surgical schedule on daily emergency department throughput time

Abstract

Study objectives: Mean emergency department (ED) throughput time per day (TPT) measured from arrival to departure is influenced by input, throughput, and output factors. Knowledge of the relative effects of these factors on TPT is important in maximizing ED efficiency. Elective operating room surgical cases compete with ED patients for inpatient beds and vary in our hospital from zero on weekends to a median of 48 on weekdays. We measure the effect of the following daily variables on TPT: (1) number of elective OR surgical cases; (2) ED volume; (3) number of ED admissions; (4) number of ED ICU admissions; (5) number of ED clinical attending hours and shifts; (6) presence of any ambulance diversion; (7) day of the week; and (8) medical-surgical hospital occupancy. Methods: Data were collected retrospectively from ED and hospital electronic logs for 24-hour periods starting at midnight for 102,327 ED visits between April 15, 2002, and February 29, 2004. TPT was compared with the independent variables by linear regression analysis. Variables reaching statistical significance at P less than .05 were further analyzed in a multiple linear regression model. Results: The following 4 variables achieved statistical significance: (1) number of elective surgical OR cases; (2) any diversion; (3) number of admissions; and (4) medical-surgical occupancy. In multivariate analysis, TPT for each patient increased by the following: 0.256 minutes (15 seconds) for every additional elective surgical case; 6.5 minutes for any diversion; 2.2 minutes for every additional admission; and 0.54 minutes (32 seconds) for every percent increase in occupancy. These 4 variables accounted for 21.1% of the variability in TPT. The median of 48 elective surgeries performed per weekday add 12.3 minutes to the TPT per patient on those days. Conclusion: The number of OR elective surgical cases on weekdays prolonged TPT by 12.3 minutes per ED patient during the study in our hospital. Reorganizing the elective surgical schedule may have a beneficial effect in decreasing TPT. The increase in TPT during diversion is presumably the result of ED crowding.