Redesign of a University Hospital Preanesthesia Evaluation Clinic Using a Queuing Theory Approach

Background: Changes in patient length of stay (the duration of one visit) as a result of the introduction of an electronic patient file system forced an anesthesia department to change their outpatient clinic organization. The aim of this study is to demonstrate how the involvement of essential employees combined with mathematical techniques to support the decision making process resulted in a successful intervention.

Methods: The setting is the preanesthesia evaluation clinic of a university hospital, where patients consult several medical professionals, either on walk-in or appointment basis. Queuing theory was used to model the initial set-up of the clinic, and later to model possible alternative designs. With the queuing model, possible improvements in efficiency could be investigated. Inputs to the model were patient arrival rates and expected service times, collected from the clinic’s logging system and by observation. The performance measures calculated with the model were patient length of stay and employee utilization rate. Supported by the model outcomes, a working group consisting of representatives of all clinic employees decided if the initial design should be maintained, or an intervention was needed.

Results: The queuing model predicted that three of the proposed alternatives would result in better performance. Key points in the intervention were the rescheduling of appointments and the reallocation of tasks. The intervention resulted in a shortening of the time the anesthesiologist needed to decide upon approving the patient for surgery. Patient arrivals increased sharply over one year by more than 16%, however patient length of stay at the clinic remained essentially unchanged. If the initial set-up of the clinic would have been maintained, the patient length of stay would have increased dramatically.

Conclusions: Queuing theory provides robust methods to evaluate alternative designs for the organization of preanesthesia evaluation clinics. Combining these mathematical techniques with the essential involvement of employees may lead to a successful intervention that improves clinic performance.