D. Jiménez Castro

Diagnostic value of adenosine deaminase in nontuberculous lymphocytic pleural effusions

Adenosine deaminase (ADA) can aid in the diagnosis of tuberculous pleural effusions, but false-positive findings from lymphocytic effusions have been reported. The purpose of this study is to assess the ADA levels in nontuberculous lymphocytic pleural effusions (lymphocyte count >50%) of different aetiologies. Altogether, 410 nontuberculous lymphocytic pleural fluid samples were consecutively selected. These included malignant effusions (n=221), idiopathic effusions (n=76), parapneumonic effusions (n=35), postcoronary artery bypass graft surgery effusions (n=6), miscellaneous exudative effusions (n=21) and transudative effusions (n=51). The ADA level reached the diagnostic cut-off for tuberculosis (40 U·L−1) in seven of the 410 cases (1.71%). The negative predictive value of ADA for the diagnosis of pleural tuberculosis was 99% (403 of 407 cases) in the group of lymphocytic pleural effusions. In five of these seven patients ADA1 and ADA2 were measured, and in all these cases (100%) ADA1/ADAp correctly classified these lymphocytic effusions as nontuberculous (ratio <0.42). This prospective study provides additional evidence that adenosine deaminase levels in nontuberculous lymphocytic pleural effusions seldom exceed the cut-off set for tuberculous effusions. The pleural fluid adenosine deaminase levels were significantly higher in different types of exudative effusions than in transudates. An adenosine deaminase level <40 IU·L−1 virtually excluded a diagnosis of tuberculosis in lymphocytic pleural effusions. Adenosine deaminase1/adenosine deaminasep correctly classified all nontuberculous lymphocytic pleural effusions with high adenosine deaminase levels.

The use of adenosine deaminase and adenosine deaminase isoenzymes in the diagnosis of tuberculous pleuritis.

The bacillary population described in tuberculous pleuritis is small, and its most likely pathogenetic mechanism is essentially immunologic. This explains why, until now, the diagnostic identification of tuberculous pleuritis (TP) has been based on the presence of granulomas in pleural biopsy. Correcting this diagnostic deficiency through other parameters related to the specific pathogenetic mechanism has been widely studied. The determination of the levels of adenosine deaminase (ADA) in pleural fluid offers high performance in its discriminating capacity to identify TP (sensitivity 87 to 100%, specificity 81 to 97%). Adenosine deaminase expresses the sum of two isoenzymes (ADA1 and ADA2). ADA1 is ubiquitous in all cells, including lymphocytes and monocytes, whereas ADA2 is found only in monocytes. Analysis and determination of these isoenzymes have shown that ADA in TP increases particularly at the expense of ADA2 and that the ADA1/ADAp activity ratio improves performance in terms of sensitivity, specificity, and efficacy (100%, 92 to 97%, and 98%, respectively) in correcting all false-negative and false-positive results except 1 to 9% of nonlymphoproliferative malignancies. Only the high performance of ADA in the identification of TP allows it to be assumed that pleural biopsy can be obviated, especially in patients aged less than 35 years of age or having a lymphocyte-to-neutrophil proportion of more than 0.75 in regions of high prevalence. Quick determination and low cost justify its routine use in exudates. The ADA1/ADAp activity ratio improves performance even more and could be used in cases with uncertain diagnoses or in regions with low prevalence of tuberculosis.

Prognostic features of residual pleural thickening in parapneumonic pleural effusions

The objective of the study was the identification of predictive factors for the development of residual pleural thickening (RPT) in patients with parapneumonic effusion. The design of the prospective study involved investigating patients with parapneumonic pleural effusions diagnosed between March 1991 and December 2000 in the respiratory department of Hospital Ramón y Cajal (Madrid, Spain) which is a 1,500 tertiary-care hospital. The clinical and radiological characteristics and measurements of microbiological and biochemical variables in the pleural fluid taken from the patients were studied. RPT was defined in a posteroanterior chest radiograph as pleural thickening of ≥10 mm measured at the lateral chest wall at the level of an imaginary line, tangent to the diaphragmatic dome. A total of 48 of the 348 patients studied (13.79%) were found to have RPT. Among the factors studied, only presence of pus in the pleural space, Fine classes IV and V, temperature ≥38°C and delayed resolution of pleural effusions after diagnosis (>15 days) were independently associated with the risk of RPT. This study showed that significant residual pleural thickening was not a common complication of parapneumonic pleural effusions. There are certain risk factors for the development of residual pleural thickening. However, this complication was not associated with long-term functional repercussions in the series of patients involved in this study.

Pleural Fluid Parameters Identifying Complicated Parapneumonic Effusions

Background: Controversy exists regarding the clinical utility of pleural fluid parameters as prognosticators of complicated parapneumonic effusions that require drainage. Objectives: The purpose of this prospective study is to further assess the utility of these parameters in the management of a larger series of parapneumonic effusions and to determine appropriate binary decision thresholds. Methods: We studied 238 consecutive patients with parapneumonic effusions who underwent diagnostic thoracentesis. Results: We found that pleural fluid pH had the highest diagnostic accuracy (area under the curve, AUC: 0.928; 95% confidence interval, CI: 0.894–0.963) compared with pleural fluid glucose (AUC: 0.835; 95% CI: 0.773–0.897), LDH (AUC: 0.824; 95% CI: 0.761–0.887) or pleural fluid volume (AUC: 0.706; 95% CI: 0.634–0.777). The optimal binary decision threshold for pleural fluid pH identifying complicated effusions requiring drainage was 7.15. Binary, multilevel and continuous likelihood ratios (LRs) for pH were calculated to estimate the likelihood of complication of the pleural effusion. Values for the LRs were compared for each of the three strategies, and relative clinical and statistical significances were assessed. Binary LRs provided significantly less information than continuous strategies. Conclusion: The pH has the highest diagnostic accuracy for identifying complicated parapneumonic pleural effusions. The binary decision threshold determining the need for chest drainage is 7.15 in our patient series. We recommend continuous LRs to estimate the post-test probability of the complication as they provide the most information compared with binary LRs. Our results do not support the use of pleural fluid LDH as independent predictor of complicated parapneumonic effusions.

Análisis comparativo de los criterios de Light y otros parámetros bioquímicos para distinguir entre exudados y trasudados

Los criterios de Light han sido empleados clasicamente para diferenciar entre exudados y trasudados pleurales. No obstante, son muchos los estudios que han tratado de identificar parametros mas eficaces. El objetivo de nuestro trabajo fue determinar la utilidad de distintos parametros bioquimicos para diferenciar entre trasudados y exudados y compararlos con los criterios mejor estudiados hasta el momento: los criterios de Light. Analizamos prospectivamente 850 casos de derrame pleural no seleccionados, con diagnostico final cerrado tras su confirmacion, respuesta terapeutica y seguimiento, recogidos de forma consecutiva en la Unidad de Pleura de nuestro hospital. Los parametros que valoramos como potencialmente discriminantes entre trasudados y exudados fueron: glucosa, proteinas, albumina, lactato deshidrogenasa (LDH), colesterol, trigliceridos, bilirrubina, fosfatasa alcalina y adenosin deaminasa (ADA), tanto individualmente como combinados entre si para obtener el maximo rendimiento. El mayor rendimiento diagnostico lo ofrece la combinacion del colesterol pleural, la LDH pleural y la relacion proteinas pleura/suero, pero sin diferencias significativas con las combinaciones del colesterol y LDH pleurales, la LDH y proteinas pleurales, los criterios de Light o los criterios de Light modificados. Recomendamos el empleo de colesterol pleural mayor de 47 mg/dl y LDH pleural mayor de 222 UI/l por ofrecer el mismo rendimiento que la combinacion de tres parametros, por su menor coste y porque evita la necesidad de determinaciones sericas.

Tromboembolismo pulmonar no sospechado en el Servicio de Urgencias

BACKGROUND AND OBJECTIVES Pulmonary embolism (PE) is a disease that sometimes has a significant delay in diagnosis. This situation may lead to an increase in morbidity and mortality in patients who have it. The aim of our study has been to define the clinical profile of patients with unsuspected PE in the emergency department and the factors that influence the delayed diagnosis. PATIENTS AND METHODS A total of 148 patients admitted with diagnosis of PE confirmed by CT (n=133) or by high-probability ventilation-perfusion scintigraphy scan (n=15) were retrospectively analyzed. They were divided into two groups: those with unsuspected disease in the emergency department (USPE) and those who it was suspected (SPE). Baseline characteristics of the patients, risk factors, signs and symptoms in the emergency department, complementary test, days of hospitalization and mortality were studied. RESULTS The USPE was found in 63/148 patients (42.6%) in the emergency department. Dyspnea and chest pain were the most frequent clinical manifestations of this disease, this being more commonly identified in the SPE group than in the USPE group, with significant differences (OR=0.4 [0.2-0.9] for dyspnea and OR=0.3 [0.2-0.7] for chest pain). However, However, the presence of thrombocytopenia (OR=3.4 [1.1-10.2], P<.05), normal electrocardiogram (EC) (OR=3.4 [1.1-10.2], P<.05), and localization of PE in right lung (OR=4.7 [2-11.3], P<.001) were risk factors for not suspect it. Days of hospitalization, days of symptoms and mortality were not statistically different between groups. CONCLUSIONS According to the results, the proportion of unsuspected PE in the emergency department was high (close to 40%). The presence of dyspnea and chest pain was associated to suspicion of SPE. On the contrary, the presence of thrombocytopenia, normal EC and right localization of PE were associated to the non-suspicion of SPE in the emergency department.

Identificación de pacientes con un tromboembolismo pulmonar de bajo riesgo

Objetivo Determinar las caracteristicas de los pacientes diagnosticados de tromboembolismo pulmonar (TEP) en el Servicio de Urgencias del Hospital Gregorio Maranon, para valorar la aplicabilidad de un modelo basado en criterios clinicos que permite identificar a pacientes con bajo riesgo de complicaciones. Material y metodos Se evaluaron todos los pacientes que ingresaron por urgencias con el diagnostico de TEP agudo. Se recogieron las siguientes variables: edad, sexo, comorbilidad (antecedentes personales de insuficiencia cardiaca, enfermedad pulmonar cronica, enfermedad renal cronica, enfermedad cerebrovascular y cancer), tension arterial, frecuencia cardiaca, saturacion arterial de oxigeno y estado mental. Tambien se recogio el tratamiento recibido y la presencia de complicaciones durante su estancia en el hospital. Se identifico como enfermos con TEP de bajo riesgo a aquellos pacientes que no presentaban ninguna de estas caracteristicas en la evaluacion inicial. Resultados Se incluyeron en el estudio 101 pacientes, de los que 16 cumplian todos los criterios para ser considerados de bajo riesgo (15,8%). Al comparar este subgrupo con el resto de los enfermos, se detectaron diferencias en la edad, que fue significativamente menor en los pacientes de bajo riesgo. Tambien se apreciaron diferencias estadisticamente significativas en la frecuencia cardiaca y en la saturacion arterial de oxigeno. Todos los pacientes, excepto 1 que se encontraba en situacion terminal, recibieron tratamiento anticoagulante. La evolucion de los enfermos durante el ingreso fue satisfactoria en el 100% de los individuos del grupo de bajo riesgo frente al 88,1% en el de pacientes de no bajo riesgo. En este ultimo grupo 7 enfermos (6,93%) presentaron complicaciones durante el ingreso y se produjeron 5 fallecimientos (4,95%). Conclusiones La aplicacion de un modelo basado en criterios clinicos permite identificar a un subgrupo de pacientes con TEP con bajo riesgo de complicaciones. Dicho subgrupo de enfermos no se beneficia por tanto de un ingreso hospitalario, con la ventaja del confort que proporciona al paciente el tratamiento ambulatorio y de la disminucion de costes que dicha estrategia supone.