St. John Hospital and Medical Center conducted a MedModel simulation study of their Pre-Op Hold (POH), Post Anesthesia Care Unit (PACU) and their overflow Annex based on expected changes to the OR surgical environment.

At the time of the study, St John was performing 15,319 surgical procedures annually in the main operating rooms. With 15 OR suites, 13 POH beds, 14 PACU beds and five Annex beds, St. John Management Engineers wanted to know if impending changes would adequately service the surgical load.

These changes included a renovation that would add four OR's, four POH beds and four PACU beds, a reduction in case schedule hours, some reassignment of cases to the Ambulatory Surgery Center, additional surgical cases and an increase in PACU length of stay due to ICU bed shortages.

The simulation study was led by Lillian Miller, St. John's Sr. Management Engineer, with input from the Director of Surgical Services, the Clinical Nurse Manager and Assistant Clinical Nurse Manager and from data supplied by the OR Scheduling Supervisor and the SurgiServe database. Data included the type of surgical cases and patient entry and exit time to each area.

The project's primary purpose was to determine if the POH, PACU and Annex bed capacity suggested in the renovation would be sufficient to meet future demands. Additionally, the study analyzed the effectiveness of the Annex beds utilized for patient overflow, the feasibility of a separate Invasive Monitoring Room and the feasibility for using Annex beds for extended stay patients.

The Approach
Eighteen different Physician Services and Patient Categories were used in the model. Available data derived the average weekly arrival rate by patient type for current patient volumes, as well as times of arrival and the expected length of stay. First, a basic model representing the current flow and configuration was developed. Patients arrive in a cycle distribution, are routed to primary and alternate locations, are moved based upon their category, and have LOS dependent on category distributions. Annex queue patients wait for routing dependent on one of three conditions: an Annex bed becomes empty, a bed in the Annex is available for the same type of patient (patient types cannot be mixed in the Annex), or a POH or PACU bed becomes available. The completed model was run for 720 hours with a 30 hour warm-up. This long run allowed the collection of value histories of patient volumes in each area. Once completed, the model was validated by OR management personnel against actual data.

Results, Alternatives & Recommendations
The basic model showed that the renovation plan (18 PACU beds) would not satisfy the future need of 20 PACU beds, but that POH and Annex beds would be underutilized. Therefore, three alternatives involving the use of the Invasive Monitoring Room for certain patient procedures, extended LOS for cardiac patients and extended LOS for recovery of certain patients were analyzed to see the impact on reducing PACU requirements and increasing Annex bed use.

The development of these models showed that the current flow of patients would not meet the future plan. The Annex was not large enough for cardiac recovery or for extended LOS for patients waiting for ICU beds. The simulation study showed that the Invasive Monitoring Room plan met the future patient volume and altered arrival pattern.

As a result of the recommendations made by the St. John Hospital and Medical Center Management Engineers, the following changes were made in the renovation plan: a wall was placed in the POH to create the four-bed Invasive Monitoring Room, a door was added to the Invasive Monitoring Room to the sterile hall so patients could be moved to the OR, and policy changes were implemented by the Anesthesia Department for inserting arterial lines.

The OR was happy to use the simulation in the analysis. MedModel made it easy to show the animation of patients going in-and-out of beds by time of day. As a result, OR management considered alternative uses of beds.

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