The operating room and central sterile supply department (CSSD) are two
resource-intensive healthcare departments. Reducing the environmental and financial impact of these departments is of great importance in the global debate on sustainability. Removing unnecessary items from instrument trays may provide a partial solution. However, improvements to tray compositions are often time-consuming, not permanent and not using the full reduction potential. This research compares different methods of medical instrument tray optimization and combines different aspects to create a new methodology. Three models compared and evaluated objective and subjective instrument use percentages and different suggestions for tray optimizations. New tray compositions, based on objective use rates, were discussed with the medical specialists and attuned to their requirements. The result
was then reviewed by the OR-assistants, before making any final adjustments. This methodology is tested for abdominal instrument trays at the gynaecology department of the Leiden University
Medical Center (LUMC). The new trays were evaluated over a test period and missing items were registered during follow-up. Risks to patient safety as a result of missing individual instruments
and chances of missing instruments for different reduction methods are discussed and quantified. Mean use rates of the designated instrument sets are 28.4% (SD=6.43%) for open surgery (n=16) and 47.6% (SD=8.16%) for minimally invasive procedures (n=12). A 37% reduction of instruments is reached across three abdominal trays by removing unnecessary items. Weight of the tray contents is reduced by 31%. During the evaluation (n=7 procedures), mean instrument use for abdominal procedures increased from 28.4% (SD=6.43%) to 46.47% (SD=10.96%) after tray optimization. A reduction based on use rates with a 10% cut-off or based on the recommendations of the medical specialists, induces an 8.7% or 3.9% chance of missing any instrument during the procedure, respectively. Tray content reductions based on OR-assistant suggestions and objective use rates with a 0% cut-off are safe, but do not utilize the complete reduction potential. Different tray optimization methods were compared. Use rates were measured in the OR and expert recommendations were discussed in group sessions. A combination of objective use rates and subjective expert considerations can lead to a significant reduction of the amount of unnecessary items in the medical instrument cycle without harming patient safety. Group consensus amongst medical specialists suggests the most radical reduction of instruments on the tray, but increases chances of missing instruments during surgery. Recommendations based on use rates have to be supplemented by reduction efforts based on the clustering of equivalent instruments. Future work should focus on ways to scale reduction efforts to an autonomous hospital-wide system and teach optimization models to mimic human expert input. It should also focus on exact measurements in the CSSD to estimate reductions in costs and CO2-footprint reliably.