Analytical models to determine room requirements in outpatient clinics

Outpatient clinics traditionally organize processes such that the doctor remains in a consultation room while patients visit for consultation, we call this the Patient-to-Doctor policy (PtD-policy). A different approach is the Doctor-to-Patient policy (DtP-policy), whereby the doctor travels between multiple consultation rooms, in which patients prepare for their consultation. In the latter approach, the doctor saves time by consulting fully prepared patients. We use a queueing theoretic and a discrete-event simulation approach to provide generic models that enable performance evaluations of the two policies for different parameter settings. These models can be used by managers of outpatient clinics to compare the two policies and choose a particular policy when redesigning the patient process.We use the models to analytically show that the DtP-policy is superior to the PtD-policy under the condition that the doctor’s travel time between rooms is lower than the patient’s preparation time. In addition, to calculate the required number of consultation rooms in the DtP-policy, we provide an expression for the fraction of consultations that are in immediate succession; or, in other words, the fraction of time the next patient is prepared and ready, immediately after a doctor finishes a consultation. We apply our methods for a range of distributions and parameters and to a case study in a medium-sized general hospital that inspired this research

From specification to measurement: the bottleneck in analog industrial testing

The translation of the specification of an analog device into the necessary set of measurements to be carried out by an industrial test facility is discussed. Algorithms are developed to compute the number of test vectors needed to guarantee a certain parameter and to compare several possible test methods based on accuracy. It is shown that the specification of a circuit can be transformed into single-parameter measurements, to be carried out by an industrial test facility. There is a tradeoff between the number of measurements and the accuracy of the specified parameter. A computationally efficient tradeoff between test methods based on maximum accuracy can be made. One of the aspects needed to make these tradeoffs, the measurement error, can be predicted using one of the proposed experiments. There is a tradeoff between the complexity of the experiment and the accuracy of the error prediction

Brine transport in porous media

In this paper we use a Von Mises transformation to study brine transport in porous media. The model involves mass balance equations for fluid and salt, Darcy's law and an equation of state, relating the salt mass fraction to the fluid density. Application of the Von Mises transformation recasts the model equations into a single nonlinear diffusion equation. A further reduction is possible if the problem admits similarity. This yields a formulation in terms of a boundary value problem for an ordinary differential equation which can be treated by semi-analytical means. Three specific similarity problems are considered in detail: (i) One-dimensional, stable displacement of fresh water and brine in a porous column, (ii) Flow of fresh water along the surface of a salt rock, (iii) Mixing of parallel layers of brine and fresh water

Tactical planning in healthcare using approximate dynamic programming

Tactical planning of resources in hospitals concerns elective patient admission planning and the intermediate term allocation of resource capacities. Its main objectives are to achieve equitable access for patients, to serve the strategically agreed number of patients, and to use resources efficiently. We propose a method to develop a tactical resource allocation and patient admission plan that takes stochastic elements into consideration, thereby providing robust plans. Our method is developed in an Approximate Dynamic Programming (ADP) framework and copes with multiple resources, multiple time periods and multiple patient groups with various uncertain treatment paths through the hospital and an uncertain number of arrivals in each time period, thereby integrating decision making for a chain of hospital resources. Computational results indicate that the ADP approach provides an accurate approximation of the value functions, and that it is suitable for large problem instances at hospitals, in which the ADP approach performs significantly better than two other heuristic approaches. Our ADP algorithm is generic, as various cost functions and basis functions can be used in various settings of tactical hospital management

Excessive gas exchange impairment during exercise in a subject with a history of bronchopulmonary dysplasia and high altitude pulmonary edema

A 27-year-old male subject (V(O2 max)), 92% predicted) with a history of bronchopulmonary dysplasia (BPD) and a clinically documented case of high altitude pulmonary edema (HAPE) was examined at rest and during exercise. Pulmonary function testing revealed a normal forced vital capacity (FVC, 98.1% predicted) and diffusion capacity for carbon monoxide (D(L(CO)), 91.2% predicted), but significant airway obstruction at rest [forced expiratory volume in 1 sec (FEV(1)), 66.5% predicted; forced expiratory flow at 50% of vital capacity (FEF(50)), 34.3% predicted; and FEV(1) /FVC 56.5%] that was not reversible with an inhaled bronchodilator. Gas exchange worsened from rest to exercise, with the alveolar to arterial P(O2) difference (AaD(O2)) increasing from 0 at rest to 41 mmHg at maximal normoxic exercise (VO(2) = 41.4 mL/kg/min) and from 11 to 31 mmHg at maximal hypoxic exercise (VO(2) = 21.9 mL/kg/min). Arterial P(O2) decreased to 67.8 and 29.9 mmHg at maximal normoxic and hypoxic exercise, respectively. These data indicate that our subject with a history of BPD is prone to a greater degree of exercise-induced arterial hypoxemia for a given VO(2) and F(I(O2)) than healthy age-matched controls, which may increase the subject's susceptibility to high altitude illness

Histopathology laboratory operations analysis and improvement

Histopathology laboratories aim to deliver high quality diagnoses based on patient tissue samples. Indicators for quality are the accuracy of the diagnoses and the diagnostic turnaround times. However, challenges exist regarding employee workload and turnaround times in the histopathology laboratory. This paper proposes a decomposed planning and scheduling method for the histopathology laboratory using (mixed) integer linear programming ((M)ILP) to improve the spread of workload and reduce the diagnostic turnaround times. First, the batching problem is considered, in which batch completion times are equally divided over the day to spread the workload. This reduces the peaks of physical work available in the laboratory. Thereafter, the remaining processes are scheduled to minimize the tardiness of orders. Preliminary results show that using this decomposition method, the peaks in histopathology workload in UMC Utrecht, a large university medical center in the Netherlands, are potentially reduced with up to 50% by better spreading the workload over the day. Furthermore, turnaround times are potentially reduced with up to 20% compared to current practices

Upper eyelid motility in blepharoptosis and in the aging eyelid

PURPOSE. To study the metrics of lid saccades in blepharoptosis and to distinguish any differences in the dynamics of eyelid movements that are related to the cause of blepharoptosis and to aging. METHODS. The lid and vertical eye saccades of 7 patients with congenital blepharoptosis and those of 18 patients with aponeurogenic blepharoptosis, either involutional or rigid-contact-lens-induced, were recorded with electromagnetic search coils. For each saccade, two parameters were assessed: amplitude and peak velocity. Two age-matched control groups were assessed in the same manner. Repeated measures analysis of variance was used to investigate any observed differences between the included groups. RESULTS. Congenital and rigid-contact-lens-induced blepharoptosis were readily distinguishable from one another, as well as from the age-matched control group, in both lid saccadic amplitude and peak velocity. For example, 40 degrees downward lid saccades in the congenital blepharoptosis group averaged 22.9 degrees +/- 4.0 degrees (SD), whereas 30.0 degrees +/- 4.7 degrees lid saccades were made by the age-matched control group. The subjects in the two groups with aponeurogenic blepharoptosis also made lid saccades that were distinctive for their group (P: < 0.02), in both amplitude and peak velocity. For 40 degrees downward saccades in involutional and rigid-contact-lens-induced blepharoptosis, lid saccadic amplitude averaged 32.7 degrees +/- 4.3 degrees and 40.3 degrees +/- 3.5 degrees, respectively. Lid saccadic peak velocity declined significantly with age. Lid saccadic peak velocity for 40 degrees upward saccades in the younger control group averaged 401.7 +/- 11.4 deg/sec, whereas the older control group achieved an average peak velocity of 360.7 +/- 60.4 deg/sec. The lid saccadic dynamics in the involutional blepharoptosis group proved to be similar (P: > 0.05) in saccadic amplitude and peak velocity to those of age-matched controls. CONCLUSIONS. In diffe

Predicting turnaround time reductions of the diagnostic track in the histopathology laboratory using mathematical modelling

Background \ud Pathology departments face a growing volume of more and more complex testing in an era where healthcare costs tend to explode and short turnaround times (TATs) are expected. In contrast, the histopathology workforce tends to shrink, so histopathology employees experience high workload during their shifts. This points to the need for efficient planning of activities in the histopathology laboratory, to ensure an equal division of workload and low TATs, at minimum costs. \ud \ud Methods \ud The histopathology laboratory of a large academic hospital in The Netherlands was analysed using mathematical modelling. Data were collected from the Laboratory Management System to determine laboratory TATs and workload performance during regular working hours. A mixed integer linear programme (MILP) was developed to model the histopathology processes and to measure the expected performance of possible interventions in terms of TATs and spread of workload. \ud \ud Results \ud The MILP model predicted that tissue processing at specific moments during the day, combined with earlier starting shifts, can result in up to 25% decrease of TATs, and a more equally spread workload over the day. \ud \ud Conclusions \ud Mathematical modelling can help to optimally organise the workload in the histopathology laboratory by predicting the performance of possible interventions before actual implementation. The interventions that were predicted by the model to have the highest performance have been implemented in the histopathology laboratory of University Medical Center Utrecht. Further research should be executed to collect empirical evidence and evaluate the actual impact on TAT, quality of work and employee stress levels