Identifying transudates misclassified by Light's criteria.

PURPOSE OF REVIEW: Light's criteria combine three dichotomous tests into a decision rule that is considered positive if any one of the tests is positive. This strategy clearly maximizes sensitivity, although at the expense of specificity. Although Light's criteria identify 98% of pleural exudates, they misclassify about 25% of transudates as exudates. The way to overcome this limitation is discussed in this review. RECENT FINDINGS: Traditionally, measurement of the protein gradient between the serum and pleural fluid has been recommended to decrease the misclassification rate of Light's criteria. A recent study demonstrated that a gradient between the albumin levels in the serum and the pleural fluid more than 1.2 g/dl performs significantly better than a protein gradient more than 3.1 g/dl to correctly categorize mislabeled cardiac effusions (83 vs. 55%). On the other hand, the accuracy of a pleural fluid to serum albumin ratio less than 0.6 excelled when compared with albumin and protein gradients in patients with miscategorized hepatic hydrothoraces (77 vs. 62 vs. 61%). SUMMARY: The simplest strategy to reveal the true transudative nature of heart failure-related effusions, labeled as exudates by Light's criteria, is to calculate the serum to pleural fluid albumin gradient. Conversely, for misclassified hepatic hydrothoraces, measurement of the pleural to serum albumin ratio is recommended. The serum to pleural fluid protein gradient should no longer be considered the preferred test for this purpose.

Treatment of complicated parapneumonic pleural effusion and pleural parapneumonic empyema.

BACKGROUND: We performed this observational prospective study to evaluate the results of the application of a diagnostic and therapeutic algorithm for complicated parapneumonic pleural effusion (CPPE) and pleural parapneumonic empyema (PPE). MATERIAL/METHODS: From 2001 to 2007, 210 patients with CPPE and PPE were confirmed through thoracocentesis and treated with pleural drainage tubes (PD), fibrinolytic treatment or surgical intervention (videothoracoscopy and posterolateral thoracotomy). Patients were divided into 3 groups: I (PD); II (PD and fibrinolytic treatment); IIIa (surgery after PD and fibrinolysis), and IIIb (direct surgery). The statistical study was done by variance analysis (ANOVA), χ2 and Fisher exact test. RESULTS: The presence of alcohol or drug consumption, smoking and chronic obstructive pulmonary disease (COPD) were strongly associated with a great necessity for surgical treatment. The IIIa group was associated with increased drainage time, length of stay and complications. No mortality was observed. The selective use of PD and intrapleural fibrinolysis makes surgery unnecessary in more than 75% of cases. CONCLUSIONS: The selective use of PD and fibrinolysis avoids surgery in more than 75% of cases. However, patients who require surgery have more complications, longer hospital stay, and more days on PD and they are more likely to require admittance to the Intensive Care Unit.

Diagnosing pleural effusions using mass spectrometry-based multiplexed targeted proteomics quantitating mid- to high-abundance markers of cancer, infection/inflammation and tuberculosis.

Pleural effusion (PE) is excess fluid in the pleural cavity that stems from lung cancer, other diseases like extra-pulmonary tuberculosis (TB) and pneumonia, or from a variety of benign conditions. Diagnosing its cause is often a clinical challenge and we have applied targeted proteomic methods with the aim of aiding the determination of PE etiology. We developed a mass spectrometry (MS)-based multiple reaction monitoring (MRM)-protein-panel assay to precisely quantitate 53 established cancer-markers, TB-markers, and infection/inflammation-markers currently assessed individually in the clinic, as well as potential biomarkers suggested in the literature for PE classification. Since MS-based proteomic assays are on the cusp of entering clinical use, we assessed the merits of such an approach and this marker panel based on a single-center 209 patient cohort with established etiology. We observed groups of infection/inflammation markers (ADA2, WARS, CXCL10, S100A9, VIM, APCS, LGALS1, CRP, MMP9, and LDHA) that specifically discriminate TB-PEs and other-infectious-PEs, and a number of cancer markers (CDH1, MUC1/CA-15-3, THBS4, MSLN, HPX, SVEP1, SPINT1, CK-18, and CK-8) that discriminate cancerous-PEs. Some previously suggested potential biomarkers did not show any significant difference. Using a Decision Tree/Multiclass classification method, we show a very good discrimination ability for classifying PEs into one of four types: cancerous-PEs (AUC: 0.863), tuberculous-PEs (AUC of 0.859), other-infectious-PEs (AUC of 0.863), and benign-PEs (AUC: 0.842). This type of approach and the indicated markers have the potential to assist in clinical diagnosis in the future, and help with the difficult decision on therapy guidance.

Parapneumonic Effusions Are Characterized by Elevated Levels of Neutrophil Extracellular Traps.

BACKGROUND: Neutrophil extracellular traps (NETs) increasingly are implicated in acute and chronic conditions involving multiple organ systems. RESEARCH QUESTION: Are NET concentrations higher in parapneumonic effusions compared with effusions of other origin and does this reflect the inflammatory nature of these effusions? STUDY DESIGN AND METHODS: Patients (N = 101) seeking hospital treatment for undifferentiated pleural effusion underwent pleural fluid classification based on cytologic analysis results, biochemical findings, microbiological characteristics, and clinical judgement. Concentrations of NET markers (extracellular DNA [eDNA], citrullinated histone H3 [citH3]), neutrophils (α-defensins), and inflammation (IL-1ß)-related proteins were quantified by enzyme-linked immunosorbent assay. Differences between groups were analyzed using the Kruskal-Wallis one-way analysis of variance. Correlations used Spearman coefficient. Receiver operating characteristic (ROC) curves were calculated. RESULTS: Effusions were classified into four groups: parapneumonic (n = 18), malignant (n = 35), transudative (n = 22), and unclassifiable (n = 26). Concentrations of NETs markers were significantly higher in the parapneumonic group compared with malignant, transudative, and unclassifiable groups (median eDNA, 12.8 ng/mL vs 0.77 ng/mL, 0.44 ng/mL, and 0.86 ng/mL [P < .001]; and median citH3, 127.1 ng/mL vs 0.44 ng/mL, 0.34 ng/mL, and 0.49 ng/mL [P < .001]). citH3 and eDNA were correlated highly with lactate dehydrogenase (LDH; Spearman r = 0.66 and r = 0.73, respectively; P < .001) and moderately negatively correlated with pH (r = -0.55 and r = -0.62, respectively; P < .001). α-Defensins and IL-1ß were higher in the parapneumonic group than in other groups (median α-defensins, 124.4 ng/mL vs 4.7 ng/mL,7 ng/mL, and 6.9 ng/mL [P < .001]; and median IL-1ß, 145 pg/mL vs 1.87 pg/mL, 1.39 pg/mL, and 2.6 pg/mL [P < .001]) and moderately correlated with LDH (r = 0.60 and r = 0.57; P < .001). ROC curves showed high sensitivity and specificity for NET markers for prediction of parapneumonic effusion. INTERPRETATION: High levels of some NET-related mediators in parapneumonic effusions correlate with inflammation. Effusions of other causes do not show high levels of NETs. These results may have treatment implications because NETs may be an important contributor to the inflammation and viscosity of parapneumonic effusions and may help us to understand the therapeutic benefit of deoxyribonuclease in empyema.

Cuban Experience with Lung Ultrasound to Diagnose and Classify Pleural Effusion in Critically Ill Patients.

Pleural effusion is a common condition in critically ill patients (both clinical and surgical). Its diagnosis and classification are important for followup of patients with cardiorespiratory difficulty. Lung ultrasound is used for this purpose, but no reports have been published on its use in Cuba with critically ill patients in intensive care units. We performed lung ultrasound on 144 such patients with cardiorespiratory illnesses, average age 54 years, predominantly men (66%; 95/144), with average APACHE II score 13.6, and 22.1% mortality risk. Patients were divided into two groups: clinical (bronchopneumonia and cardiac insufficiency) and surgical (postoperative liver and kidney transplant or vascular and cardiovascular surgery) to diagnose and classify pleural effusion according to locus (right, left and bilateral) and structural pattern (I, II A, II B, III and IV). Pleural effusions were diagnosed in 81.2% (117/144) of patients (clinical 44.4%, 52/117; surgical 55.6%, 65/117). Bilateral location was the most common (68.4%, 80/117), followed by right (23.9%, 28/117) and then left (7.7%, 9/117). Structural pattern I (anechoic appearance) was observed in 61.5% of cases (72/117); 21.4% (25/117) were II A, 12.8% (15/117) II B, 3.4% (4/117) III, and 0.9% (1/117) were IV. We found no association between pleural effusion localization and ultrasound structural pattern in clinical patients (Fisher exact test 4.2 p = 0.9). In surgical patients, however, complex ultrasound patterns (II A, II B and III) were significantly more common in bilateral forms (Fisher exact test 14.1; p = 0.009). Further studies of this type in Cuba will help provide useful data for prompt treatment and followup of these patients.

Correlación fisiopatológica, diagnóstica y terapéutica en el derrame pleural paraneumónico / Pathophysiological, diagnostic and therapeutic correlation in parapneumonic pleural effusion

Introducción: La inflamación de la pleura desencadenada por bacterias y mediada por citocinas, aumenta la permeabilidad vascular y produce vasodilatación, lo cual genera desequilibrio entre la producción de líquido pleural y su capacidad de reabsorción por eficientes mecanismos fisiológicos. La condición anterior conduce al desarrollo de derrame pleural paraneumónico. Objetivo: Exponer la importancia de la correlación fisiopatológica y diagnóstica con los pilares fundamentales de actuación terapéutica en el derrame pleural paraneumónico. Métodos: Revisión en PubMed y Google Scholar de artículos publicados hasta abril de 2021 que abordaran el derrame pleural paraneumónico, su fisiopatología, elementos diagnósticos, tanto clínicos como resultados del estudio del líquido pleural, pruebas de imágenes, y estrategias terapéuticas. Análisis y síntesis de la información: El progreso de una infección pulmonar y la producción de una invasión de gérmenes al espacio pleural favorece la activación de mecanismos que conllevan al acúmulo de fluido, depósito de fibrina y formación de septos. Este proceso patológico se traduce en manifestaciones clínicas, cambios en los valores citoquímicos y resultados microbiológicos en el líquido pleural, que acompañados de signos radiológicos y ecográficos en el tórax, guían la aplicación oportuna de los pilares de tratamiento del derrame pleural paraneumónico. Conclusiones: Ante un derrame pleural paraneumónico, con tabiques o partículas en suspensión en la ecografía de tórax, hallazgo de fibrina, líquido turbio o pus en el proceder de colocación del drenaje de tórax, resulta necesario iniciar fibrinólisis intrapleural. Cuando el tratamiento con fibrinolíticos intrapleurales falla, la cirugía video-toracoscópica es el procedimiento quirúrgico de elección(AU)

Introduction: The inflammation of the pleura triggered by bacteria and mediated by cytokines, increases vascular permeability and produces vasodilation, which generates imbalance between the production of pleural fluid and its resorption capacity by efficient physiological mechanisms. The above condition leads to the development of parapneumonic pleural effusion. Objective: To expose the importance of the pathophysiological and diagnostic correlation with the fundamental pillars of therapeutic action in parapneumonic pleural effusion. Methods: Review in PubMed and Google Scholar of articles published until April 2021 that addressed parapneumonic pleural effusion, its pathophysiology, diagnostic elements, both clinical and results of the pleural fluid study, imaging tests, and therapeutic strategies. Analysis and synthesis of information: The progress of a lung infection and the production of an invasion of germs into the pleural space favors the activation of mechanisms that lead to the accumulation of fluid, fibrin deposition and formation of septa. This pathological process results in clinical manifestations, changes in cytochemical values and microbiological results in the pleural fluid, which accompanied by radiological and ultrasound signs in the chest, guide the timely application of the pillars of treatment of parapneumonic pleural effusion. Conclusions: In the event of a parapneumonic pleural effusion, with septums or particles in suspension on chest ultrasound, finding fibrin, turbid fluid or pus in the procedure of placement of the chest drain, it is necessary to initiate intrapleural fibrinolytic. When treatment with intrapleural fibrinolytics fails, video-thoracoscopic surgery is the surgical procedure of choice(AU)

Diagnosis of malignant pleural mesothelioma from pleural fluid by Fourier transform-infrared spectroscopy coupled with chemometrics.

This study was conducted to differentiate malignant pleural mesothelioma (MPM) from lung cancer (LC) and benign pleural effusion (BPE) from pleural fluids using the diagnostic power of Fourier transform-infrared spectroscopy with attenuated total reflectance mode coupled with chemometrics. Infrared spectra of MPM (n = 24), LC (n = 20), and BPE (n = 25) were collected, and hierarchical cluster analysis (HCA) and principal component analysis (PCA) were applied to their spectra. HCA results indicated that MPM was differentiated from LC with 100% sensitivity and 100% specificity and from BPE, with 100% sensitivity and 88% specificity, which were also confirmed by PCA score plots. PCA loading plots indicated that these separations originated mainly from lipids, proteins, and nucleic acids-related spectral bands. There was significantly higher lipid, protein, nucleic acid, and glucose contents in the MPM and LC. However, the significant changes in triglyceride and cholesterol ester content, protein and nucleic acid structure, a lower membrane fluidity, and higher membrane order were only observed in the MPM. To check the classification success of some test samples/each group, soft independent modeling of class analogies was performed and 96.2% overall classification success was obtained. This approach can provide a rapid and inexpensive methodology for the efficient differentiation of MPM from other pleural effusions.

Pleural fluid analysis with traditional and additional parameters.

36 patients with pleural effusion were studied clinically with pertinent investigations and pleural fluid analysis. The pleural fluid analysis was done with routine protocol including study of traditional parameters like protein and cell count and additional parameters like pleural LDH, GOT(AST) and their ratio with serum LDH and GOT respectively. The utility of these parameters was studied critically. Amongst the isolated parameters cell count enjoyed highest (100%) specificity and positive predictive value. LDH ratio had highest (79.1%) sensitivity. Pleural LDH showed highest (52.6%) negative predictive value and diagnostic accuracy (69.4%). Amongst the combination of two parameters protein with LDH ratio had highest (87.5%) sensitivity, cell count with LDH ratio showed highest specificity (100%), positive predictive value (75%) and diagnostic accuracy (88.9%). Amongst the combination of three parameters pleural protein and cell count with LDH ratio and GOT ratio respectively enjoyed best sensitivity (87.5%), specificity and positive predictive value (100%), negative predictive value (80%) and diagnostic accuracy (90.6%). Similarly competent were the combinations offour parameters namely p rotein and cell count with LDH and its ratio and GOT and its ratio respectively. Combination of all parameters exhibited similar degree of utility.

[Pleural effusion following coronary bypass surgery].

BACKGROUND: Pleural effusion is a common finding after coronary artery bypass surgery (CABG). We sought to determine the incidence and patient characteristics predictive of its appearance, in addition to the effect of post-operative treatment with enoxaparin. METHODS: We retrospectively examined 893 patients undergoing CABG: 520 consecutive patients did not receive enoxaparin, and 373 patients received it. All early (up to 10 days) peri-operative chest radiograms were examined and graded by the amount of pleural effusion: (i) small--obliteration of the costophrenic angle; (ii) moderate-- < 50% of lung field; (iii) large-- > 50% of lung field. Patient characteristics as well as operative and post-operative parameters were analyzed in order to identify predictors for pleural effusion. RESULTS: Pleural effusion was small in 415 patients (46%), moderate in 346 (39%) and large in 132 (15%). Older age, female gender and congestive heart failure were found to be predictors for pleural effusion by multi-variate analysis (p <0.05). Routine use of enoxaparin was not found to be associated with pleural effusion after CABG. CONCLUSIONS: Over 50% of patients will develop a significant pleural effusion following CABG. Prophylactic treatment with enoxaparin does not increase the risk for pleural effusion.

The impact of between analytical platform variability on the classification of pleural effusions into exudate or transudate using Light's criteria.

BACKGROUND: Light's criteria are ratios of pleural fluid to serum total protein (TP), pleural fluid to serum lactate dehydrogenase (LDH) and pleural fluid LDH to the upper reference limit for serum LDH. They are used to classify pleural effusions into an exudate or transudate when pleural fluid protein is 25-35 g/L. We evaluated the impact of between analytical platforms on the classification of pleural effusions using Light's criteria. METHODS: Light's criteria were used to classify pleural effusions with fluid TP between 25 and 35 g/L into exudate and transudate. LDH and TP were analysed using an Abbott ARCHITECT c16000 analyser using a lactate to pyruvate method for LDH and two Roche Cobas 800 c702 analysers, one using a lactate to pyruvate method (laboratory B) and one a lactate to pyruvate method (laboratory C). RESULTS: Eighty-three paired serum and pleural fluid samples were analysed. Of these, 44 samples had a pleural fluid TP between 25 and 35 g/L and were classified according to Light's criteria. Classification of pleural fluid into transudate or exudate using different analytical platforms was 82% concordant. The LDH ratio and TP ratio were similar in laboratory B and laboratory C, but these were respectively lower (p<0.001) and higher (p<0.001) than those at laboratory A. CONCLUSIONS: Although Light's criteria are ratios, which should minimise interassay variability, we report 18% discordance between different analytical platforms. The discordance was largely due to the performance of LDH and to a lesser extent protein assays in pleural fluid. Laboratories should be aware that assays may perform differently in serum and pleural fluid.

Discriminating between transudates and exudates.

The dichotomous classification of pleural fluid as a transudate or an exudate simplifies diagnostic efforts in determining the cause of pleural effusions. Multiple pleural fluid tests are available to discriminate between these two classes of effusions. Tests commonly used in clinical practice depend on the detection in pleural fluid of large-molecular-weight chemicals that enter the pleural space to greater degrees in conditions associated with exudative compared with transudative effusions. Considerable misclassifications can occur with all available testing strategies, so clinicians benefit from adopting a nondichotomous, bayesian approach for interpreting test results.

Assessment and management of patients with pleural effusions.

This article provides an overview of the assessment and management of patients with pleural effusions. A pleural effusion is an excessive accumulation of fluid between the layers of the pleura and is a common problem caused by a variety of mechanisms and diseases.

[Adenosine deaminase activity in tuberculous and malignant pleural effusions]. / Aktywnosc deaminazy adenozyny w gruzliczym i nowotworowym wysieku w oplucnej.

Measurement of pleural adenosine deaminase activity (ADA) is a useful diagnostic tool for tuberculous pleurisy, but false-positive findings from non-tuberculous effusions have been reported. In order to improve diagnostic value of ADA it is recommended to estimate activity of both ADA1 and ADA2 izoenzymes or 2'-deoxyadenosine/adenosine activity ratio. In order to evaluate ADA as a diagnostic parameter total ADA, with adenosine as a substrate, and 2'-deoxyadenosine/adenosine activity ratio were measured in tuberculous and malignant pleural effusions. Altogether, 26 pleural exudates (11 tuberculous and 15 malignant) were selected. ADA either with adenosine or 2'-deoxyadenosine was determined by colorimetric method of Giusti. Each pleural fluid sample was diluted prior to the assay (1:8) to avoid enzyme inhibition which was observed in nondiluted pleural effusions. The ADA level reached the diagnostic cut-off set for tuberculous effusions (40 U/L) in every 11 tuberculous exudates with the mean value of 85,3+/-47,1 U/L; in 9 of these the 2'-deoxyadenosine/adenosine ratio was less than 0,45. In the malignant group of patients, no one ADA level exceed 40 U/L, being estimated at 10,6+/-7,7 U/L (p<0,001). In 10 of these 15 exudates the 2'-deoxyadenosine/adenosine ratio was undetectable, in four it was less than 0,45 and only in one it was over 0,45. We concluded that ADA measured by the Giusti method proceeded by the dilution 1:8 of the pleural effusion samples very good differentiates tuberculous from malignant pleurisy, without the necessity to determine the 2'-deoxyadenosine/adenosine ratio. The investigation needs to be continued on the more numerous groups of patients.

Proteomic study of benign and malignant pleural effusion.

BACKGROUND: Lung adenocarcinoma can easily cause malignant pleural effusion which was difficult to discriminate from benign pleural effusion. Now there was no biomarker with high sensitivity and specificity for the malignant pleural effusion. PURPOSE: This study used proteomics technology to acquire and analyze the protein profiles of the benign and malignant pleural effusion, to seek useful protein biomarkers with diagnostic value and to establish the diagnostic model. METHODS: We chose the weak cationic-exchanger magnetic bead (WCX-MB) to purify peptides in the pleural effusion, used matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) to obtain peptide expression profiles from the benign and malignant pleural effusion samples, established and validated the diagnostic model through a genetic algorithm (GA) and finally identified the most promising protein biomarker. RESULTS: A GA diagnostic model was established with spectra of 3930.9 and 2942.8 m/z in the training set including 25 malignant pleural effusion and 26 benign pleural effusion samples, yielding both 100 % sensitivity and 100 % specificity. The accuracy of diagnostic prediction was validated in the independent testing set with 58 malignant pleural effusion and 34 benign pleural effusion samples. Blind evaluation was as follows: the sensitivity was 89.6 %, specificity 88.2 %, PPV 92.8 %, NPV 83.3 % and accuracy 89.1 % in the independent testing set. The most promising peptide biomarker was identified successfully: Isoform 1 of caspase recruitment domain-containing protein 9 (CARD9), with 3930.9 m/z, was decreased in the malignant pleural effusion. CONCLUSIONS: This model is suitable to discriminate benign and malignant pleural effusion and CARD9 can be used as a new peptide biomarker.

The Diagnostic Value of the Pleural Fluid C-Reactive Protein in Parapneumonic Effusions.

Purpose. The aim of this study was to evaluate the sensitivity of pleural C-reactive protein (CRP) biomarker levels in identifying parapneumonic effusions. Methods. A single-center, retrospective review of 244 patients diagnosed with pleural effusions was initiated among patients at the Rabin Medical Center, Petah Tikva, Israel, between January 2011 and December 2013. The patients were categorized into 4 groups according to their type of pleural effusion as follows: heart failure, malignant, post-lung transplantation, and parapneumonic effusion. Results. The pleural CRP levels significantly differentiated the four groups (p < 0.001) with the following means: parapneumonic effusion, 5.38 ± 4.85 mg/dL; lung transplant, 2.77 ± 2.66 mg/dL; malignancy, 1.19 ± 1.51 mg/dL; and heart failure, 0.57 ± 0.81 mg/dL. The pleural fluid CRP cut-off value for differentiating among parapneumonic effusions and the other 3 groups was 1.38 mg/dL. The sensitivity, specificity, positive predictive value, and negative predictive value were 84.2%, 71.5%, 37%, and 95%, respectively. A backward logistic regression model selected CRP as the single predictor of parapneumonic effusion (OR = 1.59, 95% CI = 1.37-1.89). Conclusions. Pleural fluid CRP levels can be used to distinguish between parapneumonic effusions and other types of exudative effusions. CRP levels < 0.64 mg/dL are likely to indicate a pleural effusion from congestive heart failure, whereas levels ≥ 1.38 mg/dL are suggestive of an infectious etiology.

A Multiplexed Cytokeratin Analysis Using Targeted Mass Spectrometry Reveals Specific Profiles in Cancer-Related Pleural Effusions.

Pleural effusion (PE), excess fluid in the pleural space, is often observed in lung cancer patients and also forms due to many benign ailments. Classifying it quickly is critical, but this remains an analytical challenge often lengthening the diagnosis process or exposing patients to unnecessary risky invasive procedures. We tested the analysis of PE using a multiplexed cytokeratin (CK) panel with targeted mass spectrometry-based quantitation for its rapid classification. CK markers are often assessed in pathological examinations for cancer diagnosis and guiding treatment course. We developed methods to simultaneously quantify 33 CKs in PE using peptide standards for increased analytical specificity and a simple CK enrichment method to detect their low amounts. Analyzing 121 PEs associated with a variety of lung cancers and noncancerous causes, we show that abundance levels of 10 CKs can be related to PE etiology. CK-6, CK-7, CK-8, CK-18, and CK-19 were found at significantly higher levels in cancer-related PEs. Additionally, elevated levels of vimentin and actin differentiated PEs associated with bacterial infections. A classifier algorithm effectively grouped PEs into cancer-related or benign PEs with 81% sensitivity and 79% specificity. A set of undiagnosed PEs showed that our method has potential to shorten PE diagnosis time. For the first time, we show that a cancer-relevant panel of simple-epithelial CK markers currently used in clinical assessment can also be quantitated in PEs. Additionally, while requiring less invasive sampling, our methodology demonstrated a significant ability to identify cancer-related PEs in clinical samples and thus could improve patient care in the future.

Pleural adenosine deaminase in the separation of transudative and exudative pleural effusions.

OBJECTIVE: The purpose of this study was to evaluate the usefulness of a new parameter, pleural adenosine deaminase (PADA), for separating transudative pleural effusion from exudative pleural effusion, and to compare the results with other tests (albumin gradient and protein gradient). METHODS: From November 2001 to January 2003, 359 consecutive patients with pleural effusion who underwent a diagnostic thoracentesis were included in the study. Effusions were individually classified as transudates or exudates after the careful evaluation of all clinical data and biochemical parameters of pleural fluid and serum of patients on the basis of Light's criteria. The means and standard deviations of PADA, pleural/serum ADA (P/S ADA) ratio, albumin gradient and protein gradient were evaluated for transudative and exudative effusions. The best cut-off values for each test were identified by using the receiver operating characteristic (ROC) curve. The optimum cut-off level was determined by selecting points of test values that provided the greatest sum of sensitivity and specificity. RESULTS: There were 113 transudates and 246 exudates. For each test, differences in mean value between the transudate group and the exudate group were statistically significant (t test, P<0.001). The optimum cut-off levels for PADA and P/S ADA were 15.3 U/L and 0.66 U/L, respectively. ROC analysis confirmed previous recommendations for albumin gradient (12 g/L) and protein gradient (31 g/L). For detecting exudates, the PADA test yielded a sensitivity and specificity of 85.8% and 82.3%, respectively. Sensitivity and specificity of the albumin gradient were found to be 88.5% and 79.3%, and of the protein gradient 85% and 83.2%, respectively. The areas under the curve (AUC) data and accuracy demonstrated similar discriminative properties in the examined tests. CONCLUSIONS: The measurement of PADA is suggested as a reliable test in the separation of pleural exudates from transudates with accuracy similar to that of the albumin gradient and protein gradient.

Accuracy of computed tomography attenuation values in the characterization of pleural fluid: an ROC study.

RATIONALE AND OBJECTIVES: To assess the accuracy of computed tomography (CT) in characterizing pleural fluid based on attenuation values. MATERIALS AND METHODS: Protocol was approved by the local institutional review board and informed consent was waived. We retrospectively analyzed 145 pleural effusions of 145 patients (mean/standard deviation age: 60.7/15.9 years; 69 females) who underwent CT of the thorax and diagnostic thoracentesis within 7 days of each other. Effusions were classified as transudates or exudates using laboratory markers based on Light's criteria. The mean Hounsfield units (HU) of an effusion was determined by a region of interest on the three slices with the greatest anteroposterior diameter. A receiver operating characteristic curve was constructed to determine threshold values for classification on the basis of mean HU and to examine overall accuracy, using the area under the curve (A(z)). RESULTS: Of the 101 exudates and 44 transudates, the mean attenuation of exudates (17.1 HU/standard deviation 4.4) was significantly higher than transudates (12.5 HU/6.3), (P < .001). There was a modest but significant positive relationship between mean HU and laboratory markers, with the strongest relationship with pleural/serum protein (r = 0.57, P < .001) and total pleural protein (r = 0.56, P < .001). The overall accuracy of attenuation values for identifying exudates was moderate, Az = 0.775, standard error = 0.039, with the largest limitation being the overlap with transudates in the 10-20 HU range, which constituted 66% (90/145) of the total effusions measured. CONCLUSION: Although the mean attenuation of exudates is significantly higher than transudates, the clinical use of CT numbers to characterize pleural fluid is not recommended, as their accuracy is only moderate. Moreover, there is a notable overlap in attenuation values between transudates and exudates for a majority of effusions.

The relation of the pleural thickening in tuberculosis pleurisy with the activity of adenosine deaminase.

BACKGROUND: Residual pleural thickening (RPT) still occurs in most patients with tuberculosis pleurisy despite advances in the treatment of tuberculosis. The aim of this study was to evaluate the significance of RPT in tuberculosis pleurisy with the patients clinical findings, biochemical and microbiological properties of pleural effusion and with the total adenosine deaminase (ADA) and isoenzymes levels. METHODS: 121 tuberculosis pleurisy patients were evaluated retrospectively. According to posteroanterior chest x-rays, the 63 (52%) cases with the thickness 2 mm or more in lower lateral hemithorax were grouped as I and the 58 (48%) cases without pleural thickness were grouped as II. The amount of pleural effusion was classified into small, medium or massive according to their chest x-rays. In both groups; sex, age, symptoms score, bacteriological and biochemical tests and ADA levels were recorded. RESULTS: 81 (67%) male and 40 (33%) female, overall 121 patients were enrolled into the study. RPT was found higher in males (p=0.014) and the increase ran parallel with the amount of cigarette smoking (p=0.014). RPT was found to be lower in small effusions (p=0.001). The group with RPT, the serum albumin was found lower (p=0.002), pleural fluid total protein (p=0.047) and the ratio of pleural fluid protein to serum protein (p=0.002) were found higher. In group I, total ADA: 69.5 +/- 38.9 IU/L and ADA2: 41.3 +/- 31.6 IU/L were higher than the cases without RPT (p=0.032, p=0.017, respectively). CONCLUSIONS: We suggest that the immunological mechanisms are effective in the development of pleural thickening.