This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Dexter, F. Articles by Ledolter, J. Search for Related Content PubMed PubMed Citation Articles by Dexter, F. Articles by Ledolter, J. Related Collections Economics and Health Care Research Operating Rooms

---

ECONOMICS, EDUCATION, AND POLICY

Automatic Updating of Times Remaining in Surgical Cases Using Bayesian Analysis of Historical Case Duration Data and "Instant Messaging" Updates from Anesthesia Providers

Franklin Dexter, MD, PhD^*, Richard H. Epstein, MD, John D. Lee, PhD, and Johannes Ledolter, PhD

From the Division of Management Consulting, Departments of Anesthesia and Health Management and Policy, University of Iowa, Iowa City, Iowa; Department of Anesthesiology, Jefferson Medical College, Philadelphia, Pennsylvania; Departments of Mechanical and Industrial Engineering, and Management Sciences, University of Iowa, Iowa.

Address correspondence and reprint requests to Franklin Dexter, MD, PhD, Division of Management Consulting, Department of Anesthesia, University of Iowa, Iowa City, IA 52242. Address e-mail to Franklin-Dexter{at}UIowa.edu or go to web site www.FranklinDexter.net.

Abstract

BACKGROUND: Operating room (OR) whiteboards (status displays) communicate times remaining for ongoing cases to perioperative stakeholders (e.g., postanesthesia care unit, anesthesiologists, holding area, and control desks). Usually, scheduled end times are shown for each OR. However, these displays are inaccurate for predicting the time that remains in a case. Once a case scheduled for 2 h has been on-going for 1.5 h, the median time remaining is not 0.5 h but longer, and the amount longer differs among procedures.

METHODS: We derived the conditional Bayesian lower prediction bound of a case's duration, conditional on the minutes of elapsed OR time. Our derivations make use of the posterior predictive distribution of OR times following an exponential of a scaled Student t distribution that depends on the scheduled OR time and several parameters calculated from historical case duration data. The statistical method was implemented using Structured Query Language (SQL) running on the anesthesia information management system (AIMS) database server. In addition, AIMS workstations were sent instant messages displaying a pop-up dialog box asking for anesthesia providers' estimates for remaining times. The dialogs caused negotiated interruptions (i.e., the anesthesia provider could reply immediately, keep the dialog displayed, or defer response). There were no announcements, education, or efforts to promote buy-in.

RESULTS: After a case had been in the OR longer than scheduled, the median remaining OR time for the case changes little over time (e.g., 35 min left at 2:30 pm and also at 3:00 pm while the case was still on-going). However, the remaining time differs substantially among surgeons and scheduled procedure(s) (16 min longer [10th percentile], 35 min [50th], and 86 min [90th]). We therefore implemented an automatic method to estimate the times remaining in cases. The system was operational for >119 of each day's 120 5-min intervals. When instant message dialogs appearing on AIMS workstations were used to elicit estimates of times remaining from anesthesia providers, acknowledgment was on average within 1.2 min (95% confidence interval [CI] 1.1–1.3 min). The 90th percentile of latencies was 6.5 min (CI: 4.4–7.0 min).

CONCLUSIONS: For cases taking nearly as long as or longer than scheduled, each 1 min progression of OR time reduces the median time remaining in a case by <1 min. We implemented automated calculation of times remaining for every case at a 29 OR hospital.

This article has been cited by other articles:

				P. S. Stepaniak, C. Heij, G. H. H. Mannaerts, M. de Quelerij, and G. de Vries Modeling Procedure and Surgical Times for Current Procedural Terminology-Anesthesia-Surgeon Combinations and Evaluation in Terms of Case-Duration Prediction and Operating Room Efficiency: A Multicenter Study Anesth. Analg., October 1, 2009; 109(4): 1232 - 1245. [Abstract] [Full Text] [PDF]

				F. Dexter, R. H. Epstein, R. L. Elgart, and J. Ledolter Forecasting and Perception of Average and Latest Hours Worked by On-Call Anesthesiologists Anesth. Analg., October 1, 2009; 109(4): 1246 - 1252. [Abstract] [Full Text] [PDF]

				J. J. Pandit and F. Dexter Lack of Sensitivity of Staffing for 8-Hour Sessions to Standard Deviation in Daily Actual Hours of Operating Room Time Used for Surgeons with Long Queues Anesth. Analg., June 1, 2009; 108(6): 1910 - 1915. [Abstract] [Full Text] [PDF]

				A. Macario Truth in Scheduling: Is It Possible to Accurately Predict How Long a Surgical Case Will Last? Anesth. Analg., March 1, 2009; 108(3): 681 - 685. [Full Text] [PDF]