Reliability modelling of dispensing processes in community pharmacy

Studies of error rates in community pharmacies have reported error rates of between 0.014% and 3.3% per item dispensed. This suggests up to 36 million items per year may contain errors in England. In addition, literature shows that patient satisfaction with services is directly related to waiting times. There is a need for a method to model pharmacy efficiency balancing safety and waiting times, ensuring that the reliability of the dispensing process is not compromised. In this paper a Coloured Petri Net (CPN) approach is proposed for analysing reliability and efficiency of community pharmacy. A pharmacy team work to complete dispensing and non-dispensing tasks, where non-dispensing tasks require staff to be temporarily removed from the dispensing process. The proposed approach is useful to investigate what affects the error rates and long waiting times, and provides modelling-based evidence to decision makers, looking to optimise staffing levels and improve the reliability of dispensing

Applying reliability engineering techniques to the process of community pharmacy dispensing

This thesis represents 3 years of research into applying engineering techniques to the community pharmacy dispensing process. The research has been undertaken with the long-term aims of improving the reliability and efficiency of community pharmacy dispensing. A detailed Coloured Petri Net (CPN) model of the dispensing process is con- structed through an iterative process of model design and improvement. The model includes coloured tokens which are used in the CPN to track the dispensing process at a high level of detail. The main novelty of the CPN model developed in this thesis is the ability to model the reliability and efficiency of a healthcare process in a single simulation-based model. Key model outputs related to phar- macy performance include the number of prescriptions dispensed, the number of dispensing errors, and the average waiting time. Results from observations and interviews conducted at 4 UK community pharmacy sites are presented. Quantitative data was collected on the duration of individual stages of the dispensing process, and qualitative interviews about the practice were recorded with practitioners. This data collection represents a novel research contribution, to the field of pharmacy safety and efficiency, since previous work on timing individual stages of the dispensing process has not been carried out before at the same level of detail. The results of a distribution fitting analysis of the data are then used in the CPN model, when simulating a typical UK pharmacy. A modern optimisation framework, Ant Colony Optimisation (ACO), is applied to the CPN model, to ascertain optimal pharmacy set-ups. While using the CPN within the optimisation framework, the CPN model is viewed as a discrete set-up problem, where a number of decision variables are set at discrete values to produce a single pharmacy set-up. Examples of decision variables include the number of dispensers and pharmacists to employ, the checking strategy to use, and the work patten staff should follow. The optimisation problem is to find the best values of these decision variables. The main aspects of novelty in this work are: the use of a three-stage heuristic process, and the combination of CPN and ACO frameworks to tackle a community pharmacy set-up problem. This framework can be used to aid decision makers by providing a Pareto front of non-dominated community pharmacy set-ups to choose from

Reliability and efficiency evaluation of a community pharmacy dispensing process using a coloured Petri-net approach

© 2018 It has been estimated that European customers visit community pharmacies to access essential primary healthcare around 46 million times every day. Studies of dispensing error rates in community pharmacies have reported error rates of between 0.08% and 3.3% per item dispensed. While severe cases of dispensing inaccuracies often garner a high level of media coverage, less significant errors are also causing inefficiencies in primary healthcare delivery. If a variety of dispensing protocols and their consequences could be analysed using a modelling tool, the results would form the evidence for decisions on best practice guidelines in order to improve patient safety and pharmacy efficiency. This paper presents a Coloured Petri Net (CPN) modelling technique for analysing the reliability and efficiency of a community pharmacy dispensing process. The proposed approach is a novel method for considering reliability and efficiency in a single simulation based model. The CPN model represents how a team of practitioners work together to complete a set of tasks carried out in community pharmacies. It describes a close-to-reality dispensing process, which evaluates pharmacy performance over a number of key performance indicators of process reliability and efficiency, and records how staff distribute their time between tasks. Where possible, results are validated against published studies of community pharmacies

Applying reliability engineering techniques to the process of community pharmacy dispensing

This thesis represents 3 years of research into applying engineering techniques to the community pharmacy dispensing process. The research has been undertaken with the long-term aims of improving the reliability and efficiency of community pharmacy dispensing. A detailed Coloured Petri Net (CPN) model of the dispensing process is con- structed through an iterative process of model design and improvement. The model includes coloured tokens which are used in the CPN to track the dispensing process at a high level of detail. The main novelty of the CPN model developed in this thesis is the ability to model the reliability and efficiency of a healthcare process in a single simulation-based model. Key model outputs related to phar- macy performance include the number of prescriptions dispensed, the number of dispensing errors, and the average waiting time. Results from observations and interviews conducted at 4 UK community pharmacy sites are presented. Quantitative data was collected on the duration of individual stages of the dispensing process, and qualitative interviews about the practice were recorded with practitioners. This data collection represents a novel research contribution, to the field of pharmacy safety and efficiency, since previous work on timing individual stages of the dispensing process has not been carried out before at the same level of detail. The results of a distribution fitting analysis of the data are then used in the CPN model, when simulating a typical UK pharmacy. A modern optimisation framework, Ant Colony Optimisation (ACO), is applied to the CPN model, to ascertain optimal pharmacy set-ups. While using the CPN within the optimisation framework, the CPN model is viewed as a discrete set-up problem, where a number of decision variables are set at discrete values to produce a single pharmacy set-up. Examples of decision variables include the number of dispensers and pharmacists to employ, the checking strategy to use, and the work patten staff should follow. The optimisation problem is to find the best values of these decision variables. The main aspects of novelty in this work are: the use of a three-stage heuristic process, and the combination of CPN and ACO frameworks to tackle a community pharmacy set-up problem. This framework can be used to aid decision makers by providing a Pareto front of non-dominated community pharmacy set-ups to choose from

Dynamic Measurement of Patellofemoral Compression Forces: A Novel Method for Patient-Specific Patella Resurfacing in Total Knee Replacement

Functional dissatisfaction following total knee replacement (TKR) is recorded as high as 20%. The majority of these patients report anterior knee pain (AKP) as the main source of dissatisfaction. Elevated patellofemoral compression forces and soft tissue extensor hood strain have been implicated in the generation of significant AKP. A novel method of assessing and measuring patellofemoral compression forces dynamically in the native and resurfaced patella for TKR in four different quadrants of the patella is described. Results are reported from an in vitro model and cadaveric studies in the native and resurfaced knee. Patellofemoral compression forces are shown to be characteristic and consistent over repeated assessments in the native knee. Placement of a TKR significantly alters this pattern. Furthermore, over-stuffing or under-stuffing the resurfaced patella also significantly alters the nature and magnitude of patellofemoral compression forces. These studies may lead to an improved understanding of the nature of AKP following TKR, and using this assessment tool presents an opportunity to more effectively balance the third space, reproduce the native patellofemoral forces, and subsequently reduce AKP following TKR