Browsing by Author "Bischak, Diane P."

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    The Exact Fill Rate in a Periodic Review Base Stock System under Normally Distributed Demand
    (Elsevier, 2011) Silver, Edward A.; Bischak, Diane P.
    In this paper we consider a periodic review order-up-to-level (or base stock) inventory control system under normally distributed demand. For such circumstances an expression for the exact fill rate (fraction of demand satisfied without backordering) has been available in the literature but has not been widely known, let alone used by practitioners. In this paper we redevelop the expression and contrast our derivation with the earlier published one. The paper has two purposes. First, we hope that the reappearance of the exact result in this journal will lead to its wider adoption. Second, showing two contrasting approaches to obtaining the same result may be useful for both research and pedagogical purposes.
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    Queueing analysis of two healthcare systems where physician activity is offloaded to supporting health professionals
    (2020-06-30) Tagimacruz, Maria Antonieta; Bischak, Diane P.; Marshall, Deborah A.; Bijvank, Marco; Brennan, Robert William; da Silveira, Giovani J. C.; Willoughby, K. A.
    Patient waiting time to see a specialist and specialist utilization are vital aspects of providing musculoskeletal (MSK) healthcare service. Long waiting times not only subject patients to physical pain and suffering but also detrimentally impacts society. This dissertation uses queuing theory to analyze three models for rheumatologists consultation involving an alternative care provider, osteoarthritis consultation involving a musculoskeletal screener, and a central intake referral system for osteoarthritis patients. The second chapter presents a queueing and simulation approach to analyze the impact of an alternative care provider in a rheumatologist consultation system on waiting time and specialist utilization. Using a multi-class closed queueing network, we look into the boundaries for workload allocation within which performance improvements are realized. Chapter three compares an osteoarthritis consultation system with and without an MSK screener modeled as a network of queues. In addition to the impact of the addition of the MSK screener, we also investigate the impact of the surgical threshold of the screener relative to that of the surgeon to the patient waiting time and surgeon’s utilization. Finally, in the fourth chapter, we model an osteoarthritis referral central intake system and explore the impact of the deterministic and probabilistic routing decisions at the central intake on surgical patient waiting time and surgeon’s utilization.
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    Understanding and Improving Patient Flow in Outpatient Clinics and Emergency Departments
    (2018-07-19) Zaerpour, Farzad; Bischak, Diane P.; Menezes, Mozart B. C.; Bijvank, Marco; Pandes, J. Ari; Carter, Michael W.; Sabouri, Alireza
    Improving patient flow is a critical aspect of quality management in emergency departments and other healthcare settings. By improving the flow of patients in healthcare facilities, we can decrease wait times and boost patient and staff satisfaction. Many patients face physical pain and suffering while waiting for treatment in healthcare facilities. Long wait times may also result in treatable illnesses and injuries becoming chronic conditions. This dissertation includes three main chapters, corresponding to three essays on understanding and improving patient flow in outpatient clinics and emergency departments. In some outpatient clinics, lab tests must be completed before the clinic appointment, as doctors need to have the test results when seeing a patient. Achieving this tight coordination of a patient's testing and his or her subsequent doctor's appointment may be difficult in a facility where many physicians share the same testing resources. The second chapter presents a mixed-integer programming (MIP)-based approach to reduce the likelihood of a patient not completing testing in time for the clinic appointment. In the third chapter, we focus on improving patient flow in emergency departments by looking at the physician scheduling problem. We show that the scheduling of physicians has a direct impact on the waiting time of patients. Chapter 4 presents a new crowding measure in emergency departments that is based on patient volume and mix of patients. We assess the relevance and significance of the proposed measure.
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    Using Operational Analysis to Improve Access to Pulmonary Function Testing
    (2016-04-07) Ip, Ada; Asamoah-Barnieh, Raymond; Bischak, Diane P.; Davidson, Warren J.; Flemons, W. Ward; Pendharkar, Sachin R.
    Background. Timely pulmonary function testing is crucial to improving diagnosis and treatment of pulmonary diseases. Perceptions of poor access at an academic pulmonary function laboratory prompted analysis of system demand and capacity to identify factors contributing to poor access. Methods. Surveys and interviews identified stakeholder perspectives on operational processes and access challenges. Retrospective data on testing demand and resource capacity was analyzed to understand utilization of testing resources. Results. Qualitative analysis demonstrated that stakeholder groups had discrepant views on access and capacity in the laboratory. Mean daily resource utilization was 0.64 (SD 0.15), with monthly average utilization consistently less than 0.75. Reserved testing slots for subspecialty clinics were poorly utilized, leaving many testing slots unfilled. When subspecialty demand exceeded number of reserved slots, there was sufficient capacity in the pulmonary function schedule to accommodate added demand. Findings were shared with stakeholders and influenced scheduling process improvements. Conclusion. This study highlights the importance of operational data to identify causes of poor access, guide system decision-making, and determine effects of improvement initiatives in a variety of healthcare settings. Importantly, simple operational analysis can help to improve efficiency of health systems with little or no added financial investment.