University of Twente Student Theses


Optimising the use of Pyxis Medstations in the Medical Spectrum Twente

Jacobs, C.O. (2020) Optimising the use of Pyxis Medstations in the Medical Spectrum Twente.

[img] PDF
Abstract:The Medical Spectrum Twente uses automated medication dispensing systems (AMDS) in their nursing units. However, currently, these systems are not used optimally, and the reason this thesis was initiated was that nurses felt like they had to walk to the clinical pharmacy too often to pick up medications that were unavailable in the AMDS’. After performing a thorough problem analysis, this problem was not found throughout the nursing units. The average CSL was found to be 99.75% and the average FR is around 99.33%. These high inventory performances were the result of incredibly high inventory levels (a minimum of 2 weeks and a maximum of 4 weeks of demand). Apparently, another problem was in play here. This other problem manifested itself to be poor inventory accuracy. In several test samples taken, the average percentage of refills where the inventory level did not have to be adjusted by hand was 65%. These discrepancies were caused by underlying problems, such as disconnected patient systems and mechanical failures. This thesis focusses on developing a method for making these new (and reduced) inventory models, granted that the underlying problems are tackled as well. A method is developed to create fitting inventory models for a complete nursing unit. This method takes demand data from these AMDS’ and makes an inventory classification. Then, a fitting inventory policy is chosen, as well as the desired cost and service objectives. Statistical distributions are fitted to the demand and finally, decision rules are used to calculate new reorder points and order-up-to levels. By decreasing the inventory, a cost decrease is expected and room in the AMDS’ is freed up for an extended assortment. With this new assortment, nurses will have to walk to the CP less often. Additionally, a tool is included to automate as much of the method as possible. To check how the method performs and obtain a rough estimate of how much savings could be achieved, a numerical experiment is performed for which the A5 nursing unit was evaluated. For FR levels roughly similar to the current situation (99.5%), an average inventory reduction of approximately 19% in number of medications could be obtained on the A5. Here, order sizes were rounded off to logical and/or package sizes. Due to this reduction, at least several extra SKUs could be added to the assortment of the AMDS, depending on the total usage of these new SKUs. The data used, however, have very high variability. Therefore, sensitivity analyses were performed which looked at the average total inventory needed for several CSL and FR levels, and a changing variety in the data. The former analysis yielded results according to expectations: with rising CSL and FR levels, the average total inventory levels increased exponentially. For decreasing variability, the average total inventory also decreased, supporting the notion that if somehow the variability in the data could be lowered, more accurate inventory models could be made that require less inventory to be kept, thus creating even more room for additional SKUs. To get more SKUs into the assortment of the Pyxis’, the inventory levels of the SKUs already in the Pyxis’ should be reduced. This is possible with the method described in this thesis. However, these lower inventory levels can only be implemented if inventory management and inventory accuracy are improved. This task was considered outside of the scope of this thesis, but suggestions on what to improve can be made. Perhaps one of the most important suggestions is to connect the patient system and the Pyxis systems, which will allow faster and more accurate medication retrieval. On top of that, EAV packages should be ordered as much as possible.
Item Type:Essay (Bachelor)
Faculty:BMS: Behavioural, Management and Social Sciences
Programme:Industrial Engineering and Management BSc (56994)
Link to this item:
Export this item as:BibTeX
HTML Citation
Reference Manager


Repository Staff Only: item control page