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CONTEXT: A previous study suggested that the combination of a normal D-dimer assay and normal alveolar dead-space fraction is a highly sensitive screening test for pulmonary embolism (PE). OBJECTIVE: To determine if the combination of a normal alveolar dead-space fraction (volume of alveolar dead space/tidal volume =20%) and a normal whole-blood agglutination D-dimer assay can exclude PE in emergency department (ED) patients. DESIGN: Prospective, noninterventional study conducted in 1998-1999. Study data were obtained prior to standard testing for PE, consisting of radionuclide lung scanning or contrast-enhanced computed tomography and 6-month follow-up plus selective use of venous ultrasonography and pulmonary angiography. Imaging studies were interpreted by blinded observers. SETTING: Six urban teaching hospitals in the United States. PATIENTS: A total of 380 hemodynamically stable ED patients aged 18 years or older with suspected acute PE. MAIN OUTCOME MEASURES: Sensitivity and specificity for PE with a positive test defined as having either alveolar dead-space fraction or D-dimer assay results abnormal. Alveolar dead-space fraction was determined by subtracting airway dead space from physiological dead space (determined using the modified Bohr equation) and D-dimer assay, assayed at bedside using 20 microL of arterial blood. RESULTS: Pulmonary embolism was diagnosed in 64 patients (16.8%), of those 20 had an abnormal D-dimer assay result, 3 had an abnormal alveolar dead-space fraction, 40 had abnormal results in both, and 1 had normal results for both tests. The sensitivity for diagnosis of PE was 98.4% (95% confidence interval [CI], 91.6%-100.0%). Among the 316 patients without PE, both D-dimer and dead-space results were normal in 163, for a specificity of 51.6% (95% CI, 46.1%-57.1%). Posterior probability of PE with normal results on both tests was 0.75% (95% CI, 0%-3.4%). CONCLUSION: In this multicenter study of ED patients, a normal D-dimer assay result plus a normal alveolar dead-space fraction was associated with a low prevalence of PE.
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Productos de Degradación de Fibrina-Fibrinógeno/análisis , Sistemas de Atención de Punto , Embolia Pulmonar/diagnóstico , Pruebas de Función Respiratoria , Volumen de Ventilación Pulmonar , Adulto , Anciano , Servicio de Urgencia en Hospital , Femenino , Humanos , Funciones de Verosimilitud , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Estudios Prospectivos , Alveolos Pulmonares , Sensibilidad y EspecificidadRESUMEN
How many underlying characteristics (or factors) does a set of survey questions measure? When subjects answer a set of self-report questions, is it more appropriate to analyze the questions individually, to pool responses to all of the questions to form one global score, or to combine subsets of related questions to define multiple underlying factors? Factor analysis is the statistical method of choice for answering such questions. When researchers have no idea beforehand about what factors may underlie a set of questions, they use exploratory factor analysis to infer the best explanatory model from observed data "after the fact." If, on the other hand, researchers have a hypothesis beforehand about the underlying factors, then they can use confirmatory factor analysis (CFA) to evaluate how well this model explains the observed data and to compare the model's goodness-of-fit with that of other competing models. This article describes the basic rules and building blocks of CFA: what it is, how it works, and how researchers can use it. The authors begin by placing CFA in the context of a common research application-namely, assessing quality of medical outcome using a patient satisfaction survey. They then explain, within this research context, how CFA is used to evaluate the explanatory power of a factor model and to decide which model or models best represent the data. The information that must be specified in the analysis to estimate a CFA model is highlighted, and the statistical assumptions and limitations of this analysis are noted. Analyzing the responses of 1,614 emergency medical patients to a commonly-used "patient satisfaction" questionnaire, the authors demonstrate how to: 1) compare competing factor-models to find the best-fitting model; 2) modify models to improve their goodness-of-fit; 3) test hypotheses about relationships among the underlying factors; 4) examine mean differences in "factor scores"; and 5) refine an existing instrument into a more streamlined form that has fewer questions and better conceptual and statistical precision than the original instrument. Finally, the role of CFA in developing new instruments is discussed.
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Interpretación Estadística de Datos , Medicina de Emergencia , Análisis Factorial , Proyectos de Investigación , InvestigaciónRESUMEN
Variations in the way that data are entered in ED record systems impede the use of ED records for direct patient care and deter their reuse for many other legitimate purposes. To foster more uniform ED data, the Centers for Disease Control and Prevention's (CDC) National Center for Injury Prevention and Control is coordinating a public-private partnership that has developed recommended specifications for many observations, actions, instructions, conclusions, and identifiers that are entered in ED records. The partnership's initial product. Data Elements for Emergency Department Systems, Release 1.0 (DEEDS), is intended for use by individuals and organizations responsible for ED record systems. If the recommended specifications are widely adopted, then problems--such as data incompatibility and high costs of collecting, linking, and using data--can be substantially reduced. The collaborative effort that led to DEEDS, Release 1.0 sets a precedent for future review and revision of the initial recommendations.
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Servicio de Urgencia en Hospital , Registros Médicos/normas , Humanos , Registro Médico Coordinado/normas , Sistemas de Registros Médicos Computarizados/normasRESUMEN
Variations in the way that data are entered in emergency department record systems impede the use of ED records for direct patient care and deter their reuse for many other legitimate purposes. To foster more uniform ED data, the Centers for Disease Control and Prevention's National Center for Injury Prevention and Control is coordinating a public-private partnership that has developed recommended specifications for many observations, actions, instructions, conclusions, and identifiers that are entered in ED records. The partnership's initial product, Data Elements for Emergency Department Systems, Release 1.0 (DEEDS), is intended for use by individuals and organizations responsible for ED record systems. If the recommended specifications are widely adopted, then problems--such as data incompatibility and high costs of collecting, linking, and using data--can be substantially reduced. The collaborative effort that led to DEEDS, Release 1.0 sets a precedent for future review and revision of the initial recommendations.
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Servicio de Urgencia en Hospital , Registros Médicos/normas , Humanos , Registro Médico Coordinado/normas , Sistemas de Registros Médicos Computarizados/normasRESUMEN
To identify perceptions that predict overall patient (dis)satisfaction with Emergency Department (ED) care, we studied responses to a survey mailed to all discharged patients over a 6-month period (Academic Hospital), and to a telephone interview of a random sample of discharged patients over a 1-year period (Community Hospital). The survey and interview both assessed overall satisfaction, as well as satisfaction with perceived waiting times, information delivery, and expressive quality of physicians, nurses, and staff. Data for 1176 patients (training sample) and 1101 patients (holdout sample) who rated overall satisfaction as either "very good" or "very poor" (Academic Hospital), and for 856 patients (training sample) and 431 patients (holdout sample) who rated overall satisfaction as either "excellent" or "poor" (Community Hospital), were retained for analysis. For both hospitals, nonlinear tree models efficiently achieved overall classification accuracy exceeding 98% in training analysis and 95% in holdout analysis (all p < .0001). The findings suggest that overall patient (dis)satisfaction with care received in the ED is nearly perfectly predictable on the basis of patient-rated expressive qualities of ED staff, particularly physicians and nurses. Interventions designed to reinforce positive (and extinguish negative) expressive health-care provider behaviors may cut the number of extremely dissatisfied patients in half.
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Servicio de Urgencia en Hospital/normas , Hospitales Comunitarios/normas , Hospitales Universitarios/normas , Satisfacción del Paciente/estadística & datos numéricos , Garantía de la Calidad de Atención de Salud/métodos , Chicago , Servicio de Urgencia en Hospital/organización & administración , Servicio de Urgencia en Hospital/estadística & datos numéricos , Femenino , Encuestas de Atención de la Salud , Humanos , Entrevistas como Asunto , Modelos Logísticos , Masculino , Variaciones Dependientes del Observador , Relaciones Médico-Paciente , Distribución Aleatoria , Encuestas y CuestionariosRESUMEN
Activated charcoal is often given through small-bore tubing for pediatric patients or in attempts to bypass the stomach in patients who are vomiting. The viscosity makes activated charcoal difficult to administer through small-bore tubing. This in vitro study examined several interventions to facilitate flow of aqueous suspension activated charcoal through the small-bore tubing. Aqueous suspension activated charcoal with or without sorbitol had similar flow rates. Precoating the tubing with mineral oil gave only minimal increases in flow rate. A 10% dilution decreased the time to administer 240 ccs of aqueous suspension activated charcoal by 2/3. An additional 10% dilution reduced the time to administer the same dose a further 50%. Minimal dilution of aqueous suspension activated charcoal with tap water greatly increased flow rate through small-bore tubes.
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Carbón Orgánico/administración & dosificación , Sistemas de Liberación de Medicamentos/métodos , Intubación Gastrointestinal , Química Farmacéutica , Niño , Humanos , Suspensiones , ViscosidadRESUMEN
Acetaminophen undergoes toxic conversion in the liver to a free-radical intermediary which binds to glutathione. N-Acetylcysteine acts as a glutathione precursor when natural stores are depleted, and is an effective antidote for acetaminophen overdose. Mushrooms containing amatoxins (such as Amanita phalloides) may undergo similar toxic conversion. However, in our amatoxin-poisoned mouse model, N-acetylcysteine (1.2 g kg-1) produced no change in survival or hepatic enzyme elevation compared to control animals. We conclude that N-acetylcysteine has no clinical role in the treatment of Amanita phalloides ingestion.
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Acetilcisteína/metabolismo , Amanitinas/envenenamiento , Amanitinas/antagonistas & inhibidores , Animales , Femenino , Hígado/enzimología , Ratones , Modelos Biológicos , Análisis de SupervivenciaRESUMEN
Dextromethorphan, a common ingredient in cough syrups, has rarely been described to cause toxicity. The authors describe an unusual case of a known asthmatic presenting with somnolence, who appeared to be in end-stage respiratory failure. Her partial response to routine naloxone, 1 mg, was surprising. However, additional naloxone was required to completely normalize the patient's mental status. The authors suggest naloxone be administered in doses of 0.4 mg or more intravenously in suspected dextromethorphan overdose.
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Antídotos/uso terapéutico , Dextrometorfano/envenenamiento , Naloxona/uso terapéutico , Adolescente , Adulto , Antitusígenos/análisis , Antitusígenos/envenenamiento , Preescolar , Dextrometorfano/análisis , Sobredosis de Droga , Femenino , Humanos , Lactante , Masculino , Intoxicación/complicaciones , Intoxicación/tratamiento farmacológicoRESUMEN
The magnitude and rapidity of response to epinephrine given by various routes were evaluated using a new model of bradycardia and hypotension. In ten animals, left ventricular (LV) injection of 10 micrograms/kg of epinephrine was superior to right ventricular (RV) injection in regard to time to attain a 20% increase in heart rate (HR), a 10% increase in mean arterial pressure (MAP) and time to reach peak MAP, although the peak MAP itself did not significantly differ. Similar results occurred with a 15 micrograms/kg dose. Aortic injection in seven of the animals resulted in a much longer time to target HR, an equal time to target MAP and a longer time to peak MAP compared to LV injection. LV injection of epinephrine results in a significantly more rapid onset of action than RV injection in the bradycardic, hypotensive animal. Epinephrine's beneficial effect appears to be derived from its vasoconstrictive, chronotropic and inotropic properties.
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Epinefrina/administración & dosificación , Paro Cardíaco/tratamiento farmacológico , Resucitación , Animales , Aorta , Bradicardia/tratamiento farmacológico , Perros , Epinefrina/uso terapéutico , Femenino , Ventrículos Cardíacos , Hipotensión/tratamiento farmacológico , Inyecciones , Inyecciones Intraarteriales , Factores de TiempoRESUMEN
Phalloidin, a toxin of the mushroom Amanita phalloides, was felt to act as a pro-toxin, converted by hepatic microsomal mixed function oxidase enzymes. Therefore, pretreatment with cimetidine, a potent P450 cytochrome system inhibitor, might be expected to prevent the toxic conversion. In our mouse animal model of phalloidin exposure, pretreatment with 120 mg cimetidine/kg ip failed to improve survival compared to placebo pretreatment. Moreover, cimetidine pretreatment decreased survival (p less than 0.03). These results support an alternate mechanism for phalloidin toxicity, ie, that the toxic effects are related to the interaction of phalloidin with F-actin.
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Cimetidina/farmacología , Inhibidores Enzimáticos del Citocromo P-450 , Microsomas Hepáticos/efectos de los fármacos , Faloidina/toxicidad , Actinas/metabolismo , Animales , Interacciones Farmacológicas , Activación Enzimática/efectos de los fármacos , Femenino , Dosificación Letal Mediana , Ratones , Ratones Endogámicos , Microsomas Hepáticos/enzimología , Modelos BiológicosRESUMEN
A technique for chronic implantation of a device for long-term continuous, quantitative monitoring of intraocular pressure (IOP) in experimental animals is presented. The methodology employed is straight forward and should be easily duplicated for experimental investigations where such monitoring might be useful. Continuous IOP data recorded from the device implanted in a conscious adult rhesus monkey are compared with continuous IOP data reported by other investigators.