44 research outputs found
Maximizing Operating Room Performance Using Portfolio Selection
The operating room (OR) is responsible for most hospital admissions and is one of the most cost and work intensive areas in the hospital. From recent trends, we observe an ironic parallel increase among expenditure and waiting time. Therefore, improving OR scheduling has become obligatory, particularly in terms of patient flow and benefit. Most of the hospitals rely on average patient arrivals and processing times in OR planning. But in practice, variations in arrivals and processing times causes high instability in OR performance. Our model of optimization provides OR schedules maximizing patient flow and benefit at a fixed level of risk using portfolio selection. The simulation results show that the performance of the OR has a direct relationship with the risk
BeWith: A Between-Within Method to Discover Relationships between Cancer Modules via Integrated Analysis of Mutual Exclusivity, Co-occurrence and Functional Interactions
The analysis of the mutational landscape of cancer, including mutual
exclusivity and co-occurrence of mutations, has been instrumental in studying
the disease. We hypothesized that exploring the interplay between
co-occurrence, mutual exclusivity, and functional interactions between genes
will further improve our understanding of the disease and help to uncover new
relations between cancer driving genes and pathways. To this end, we designed a
general framework, BeWith, for identifying modules with different combinations
of mutation and interaction patterns. We focused on three different settings of
the BeWith schema: (i) BeME-WithFun in which the relations between modules are
enriched with mutual exclusivity while genes within each module are
functionally related; (ii) BeME-WithCo which combines mutual exclusivity
between modules with co-occurrence within modules; and (iii) BeCo-WithMEFun
which ensures co-occurrence between modules while the within module relations
combine mutual exclusivity and functional interactions. We formulated the
BeWith framework using Integer Linear Programming (ILP), enabling us to find
optimally scoring sets of modules. Our results demonstrate the utility of
BeWith in providing novel information about mutational patterns, driver genes,
and pathways. In particular, BeME-WithFun helped identify functionally coherent
modules that might be relevant for cancer progression. In addition to finding
previously well-known drivers, the identified modules pointed to the importance
of the interaction between NCOR and NCOA3 in breast cancer. Additionally, an
application of the BeME-WithCo setting revealed that gene groups differ with
respect to their vulnerability to different mutagenic processes, and helped us
to uncover pairs of genes with potentially synergetic effects, including a
potential synergy between mutations in TP53 and metastasis related DCC gene
An Optimization Model for Operating Room Scheduling to Reduce Blocking Across the Perioperative Process
Operating room (OR) scheduling is important. Because of increasing demand for surgical services, hospitals must provide high quality care more efficiently with limited resources. When constructing the OR schedule, it is necessary to consider the availability of downstream resources, such as intensive care unit (ICU) and post anaesthesia care unit (PACU). The unavailability of downstream resources causes blockings between every two consecutive stages. In this paper we address the master surgical schedule (MSS) problem in order to minimize blockings between two consecutive stages. First, we present a blocking minimization (BM) model for the MSS by using integer programming, based on deterministic data. The BM model determines the OR block schedule for the next day by considering the current stage occupancy (number of patients) in order to minimize the number of blockings between intraop and postop stages. Second, we test the effectiveness of our model under variations in case times and patient arrivals, by using simulation. The simulation results show that our BM model can significantly reduce the number of blockings by 94% improvement over the base model. Scheduling patient flow across the 3-stage periop process can be applied to work flow scheduling for the s-stage flow shop shop production in manufacutirng, and also Smoothing patient flow in periop process can be applied to no-wait flow shop production
Stochastic BI-Level Optimization Models for Efficient Operating Room Planning
Within a hospital, the operating room (OR) department has the largest cost and revenue. Because of the aging population, the demand for surgical services has been increasing sharply in recent years. At the other hand, the rate of OR capacity expansion is lower than the rate of increasing demand. As a result, OR managers must leverage their resources by efficient OR planning. OR planning is challenging because of multiple competing\conflicting objectives such cost minimization and throughput maximization. Inherent uncertainty in the surgical procedures and patients arrivals complicate the decision making process. This increases the risk of non-realization of the system objectives. In this paper, stochastic bi-level optimization models were formulated to optimize total cost and throughput of ORs under the presence of uncertainties in patient arrivals and case times. Newsvendor model and chance-constrained optimization method were used to optimize multiple objectives under the presence of uncertainties. Using historical data, a simulation model was established to validate the results of optimization models. Using statistical process control (SPC) stability of each model was investigated. Using bi-level optimization, we addressed managerial preferences over total cost and throughput. Optimizing one objective may lead to compromise on the optimality of the other objective, which generates trade-offs. Using a trade-off balancing model, we found solutions that minimize the sum of deviations from the best solutions for both total cost and throughput. Trade-off balancing optimization models may lead to better solutions, compared to traditional multi-objective optimization models. The results of this paper are applicable to manufacturing systems, where managers face multiple objectives and uncertainties in the system
Scheduling the hospital-wide flow of elective patients
In this paper, we address the problem of planning the patient flow in hospitals subject to scarce medical resources with the objective of maximizing the contribution margin. We assume that we can classify a large enough percentage of elective patients according to their diagnosis-related group (DRG) and clinical pathway. The clinical pathway defines the procedures (such as different types of diagnostic activities and surgery) as well as the sequence in which they have to be applied to the patient. The decision is then on which day each procedure of each patient’s clinical pathway should be done, taking into account the sequence of procedures as well as scarce clinical resources, such that the contribution margin of all patients is maximized. We develop two mixed-integer programs (MIP) for this problem which are embedded in a static and a rolling horizon planning approach. Computational results on real-world data show that employing the MIPs leads to a significant improvement of the contribution margin compared to the contribution margin obtained by employing the planning approach currently practiced. Furthermore, we show that the time between admission and surgery is significantly reduced by applying our models