Diagnostic Closure Research Articles

“Paramedics are Bringing in a Hypotensive Gastrointestinal Bleeder”: An Unexpected Diagnosis

Background: Acute esophageal rupture is a rare emergency that must be diagnosed quickly and treated aggressively to avoid significant morbidity and mortality. The typical presentation of this disease includes chest pain, and the diagnosis is challenging when cardinal features such as this are absent. Objectives: This case report discusses an atypical presentation of esophageal rupture in a patient with a predisposing condition and highlights the diagnostic and cognitive difficulties involved in making the appropriate diagnosis. Case Report: We report a case of a 51-year-old woman who presented to the Emergency Department with hypotension and an emergency medical services report of hematemesis. The patient had a documented history of upper gastrointestinal bleeding and Zollinger-Ellison syndrome during her past hospitalizations; however, the patient was not anemic and had a negative stool guiac despite symptoms for 3 days. A subsequent chest radiograph led to the diagnosis of esophageal rupture with a bilateral pneumothorax requiring thoracostomies. She reported no chest pain. Conclusions: The esophageal rupture and subsequent hypotension was likely secondary to the combination of her Zollinger-Ellison syndrome and recent vomiting episodes. It is important to avoid premature diagnostic closure and think about unusual presentations of emergent conditions such as esophageal rupture.

Cognitive strategies: a method to reduce diagnostic errors in ER

I wonder why sometimes we are able to rapidly recognize patterns of disease presentation, formulate a speedy diagnostic closure, and go on with a treatment plan. On the other hand sometimes we proceed studing in deep our patient in an analytic, slow and rational way of decison making. Why decisions sometimes can be intuitive, while sometimes we have to proceed in a rigorous way? What is the “back ground noise” and the “signal to noise ratio” of presenting sintoms? What is the risk in premature labeling or “closure” of a patient? When is it useful the “cook-book” approach in clinical decision making? The Emergency Department is a natural laboratory for the study of error” stated an author. Many studies have focused on the occurrence of errors in medicine, and in hospital practice, but the ED with his unique operating characteristics seems to be a uniquely errorprone environment. That's why it is useful to understand the underlying pattern of thinking that can lead us to misdiagnosis. The general knowledge of thought processes gives the psysician awareness an the ability to apply different tecniques in clinical decision making and to recognize and avoid pitfalls.

Viruses and other infections in stillbirth: what is the evidence and what should we be doing?

In Australia, as in other developed countries, approximately 40-50% of stillbirths are of unknown aetiology. Emerging evidence suggests stillbirths are often multifactorial. The absence of a known cause leads to uncertainty regarding the risk of recurrence, which can cause extreme anguish for parents that may manifest as guilt, anger or bewilderment. Further, clinical endeavours to prevent recurrences in future pregnancies are impaired by lack of a defined aetiology. Therefore, efforts to provide an aetiological diagnosis of stillbirth impact upon all aspects of care of the mother, and inform many parts of clinical decision making. Despite the magnitude of the problem, that is 7 stillbirths per 1000 births in Australia, diagnostic efforts to discover viral aetiologies are often minimal. Viruses and other difficult to culture organisms have been postulated as the aetiology of a number of obstetric and paediatric conditions of unknown cause, including stillbirth. Reasons forwarded for testing stillbirth cases for infectious agents are non-medical factors, including addressing all parents' need for diagnostic closure, identifying infectious agents as a sporadic cause of stillbirth to reassure parents and clinicians regarding risk for future pregnancies, and to reduce unnecessary testing. It is clear that viral agents including rubella, human cytomegalovirus (CMV), parvovirus B19, herpes simplex virus (HSV), lymphocytic choriomeningitis virus (LCMV), and varicella zoster virus (VZV) may cause intrauterine deaths. Evidence for many other agents is that minimal or asymptomatic infections also occur, so improved markers of adverse outcomes are needed. The role of other viruses and difficult-to-culture organisms in stillbirth is uncertain, and needs more research. However, testing stillborn babies for some viral agents remains a useful adjunct to histopathological and other examinations at autopsy. Modern molecular techniques such as multiplex PCR, allow searches for multiple agents. Now that such testing is available, it is important to assess the clinical usefulness of such testing.

Variability of precipitation intensity: sensitivity to treatment of moist convection in an RCM and a GCM

The present study investigates the sensitivity of the frequency distribution of precipitation rates to the closure employed in the penetrative mass flux cumulus parameterization of Zhang and McFarlane in the Canadian regional climate model (CRCM) and in the Canadian Centre for Climate Modelling and Analysis third generation global atmospheric general circulation model (AGCM3). The effects of an alternative prognostic closure for mass flux cumulus parameterization in place of the original diagnostic closure are investigated. A set of experiments is performed in which changes in the frequency distribution of precipitation rates and cloud base mass-flux are examined as a function of the parameters that define each closure scheme. The relationship between the frequency distribution of precipitation and cloud base mass flux is examined and a self-consistent relation is found when the depth of convection is taken into account. Experiments performed with the prognostic closure favor relatively strong cloud base mass-flux and deep penetrative convection with relatively more intense convective precipitation. The mean of the frequency distribution of convective precipitation is larger and the heavier events become more intense. Also, experiments performed with the prognostic closure favor less frequent convective activity. However these changes in the distribution of convective component of precipitation are generally offset by opposite changes in the distribution of the resolved large-scale component of precipitation, resulting in relatively smaller changes in total precipitation. The altered partition of precipitation between convective and large-scale components is found to alter the energy balance and the thermodynamic equilibrium structure of the troposphere. The robustness found in the CRCM results regarding the sensitivity of the frequency distribution of precipitation to changes in the closure of the deep convection parameterization is investigated by performing a similar analysis of AGCM3 simulations. A remarkable similarity of AGCM3 and CRCM results is found suggesting that the closure sensitivity identified in this study is robust.

Simulation of a Round Jet and a Plume in a Regional Atmospheric Model

The mean flow characteristics of a turbulent round jet and a plume are simulated in a high-resolution regional atmospheric model. The model used for the study is the Advanced Regional Prediction System (ARPS). It is observed that the predicted flow characteristics are very sensitive to the turbulence closure scheme used. Among the three closure options in ARPS, namely, the constant eddy viscosity scheme, the Smagorinsky diagnostic closure, and the 1.5-order total kinetic energy scheme, the constant eddy viscosity scheme predicts the jet characteristics in better agreement with experiments. For the plume, all three schemes are unsatisfactory. It is shown that a modification of the constant eddy viscosity scheme incorporating a length-scale variation as suggested by theory predicts plume characteristics in good agreement with experiments. The simulations are carried out at one fixed grid-box size and flow inlet conditions; extending the present simulation results to other cases is discussed.

Stable Nocturnal Boundary Layers: A Comparison of One-Dimensional and Large-Eddy Simulation Models

A one-dimensional model and a large-eddy simulation (LES) model are used to simulate the turbulence structure of a stably stratified atmospheric boundary layer. The results are compared with those obtained by Andren (1995) using a similar three-dimensional model and with experimental data. The one-dimensional model solves the fundamental equations of momentum, entropy and conservation of two scalars, and a diagnostic second-order closure model is used to determine the turbulent fluxes of the variables as well as the variances of the velocity and scalars. The two LES models differ in the definition of the sub-grid scale scheme. The comparison of the model results outlines the differences and the similarities between the three- and the one-dimensional simulations. Although the results of the two LES models differ in the description of some of the stable boundary layer turbulence features, it is shown that good agreement is obtained with local-similarity theory and experimental data. The differences between the results of three models relate to the stratification within the layer, the asymptotic value of the various turbulent variables for large stability regimes and their values close to the surface.

Diagnostic closure and the spread of uncertainty.

When a child is diagnosed with a life-threatening, chronic illness, the taken-for-granted world of the child's parents is destroyed. From that moment on, they must learn to manage life under very uncertain conditions. The findings reported here are from a more comprehensive grounded theory study that sought a plausible explanation for parental behavior under conditions of sustained uncertainty. This report describes the emergence of uncertainty as a multidimensional concept that permeates every aspect of family life following the diagnostic announcement. The noncategorical nature of the dimensions of uncertainty found in all life-threatening, chronic childhood illnesses provides a strong argument for preparing nurses in specialties that are conceptually, rather than medically, based.