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Relationship between pleural fluid and serum cholesterol levels.

INTRODUCTION: Since the criteria of Light and colleagues for differentiating transudates and exudates were described, other tests, including the pleural fluid (PF) cholesterol test, have been proposed for the same purpose. However, the factors influencing PF cholesterol levels have not been clearly delineated. PURPOSE: To analyze the relationships among total cholesterol (CHOL), low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and triglycerides (TRIG) in serum (S) and PF. METHODS: PF and S from 99 patients (transudates, 13 patients; exudates, 86 patients) were analyzed for CHOL, HDL, LDL, TRIG, apolipoprotein AI, apolipoprotein B, and protein. The relationship between the PF and S level for each of these measurements was analyzed with linear regression and multiple regression using the ratio of PF to S protein for that measurement as a second independent variable. RESULTS: This study demonstrated that CHOL levels in PF are related to S cholesterol levels and to the permeability of the pleura (r = 0.88; p < 0.001). However, the percentage of CHOL associated with LDL and HDL (56%) in the PF was much lower than that associated with LDL and HDL in S (93%), suggesting that lipoproteins are modified once they enter the pleural space. The PF TRIG was not closely related to its S level or to the PF/S protein ratio (r = 0.49). CONCLUSION: PF cholesterol levels can be closely predicted from the S cholesterol levels and the permeability of the pleura, as reflected by the ratio of PF protein to S protein. Therefore, the CHOL ratio should not provide additional information to that provided by the protein ratio when trying to differentiate transudates from exudates. PF lipoproteins (LDL and HDL) undergo metabolic alterations once they enter the pleural space. PF TRIG levels are not closely related to S levels or to the permeability of the pleura.

Apolipoprotein A-I↗

Erroneous classification of a pleural effusion. The role of a traumatic thoracentesis.

The separation of pleural effusions into exudates and transudates is based on the pleural fluid LDH and protein content compared to the simultaneous serum LDH and protein content. A patient in biventricular failure presented with a right pleural effusion that met the criteria of a transudate. After a traumatic thoracentesis the fluid met the criteria of an exudate.

Aged↗

Pleural effusion: comparison of clinical judgment and Light's criteria in determining the cause.

Pleural fluid analysis is often the initial diagnostic test used to determine the cause of a pleural effusion. We prospectively studied 33 consecutive patients with pleural effusions to determine whether the fluid arose from a transudative or an exudative process. Clinical judgment by an internist before thoracentesis and both serum and pleural fluid protein and lactic dehydrogenase levels (commonly referred to as "Light's criteria") were compared to the patient's final diagnosis. The internist correctly classified 15 of 17 exudative processes and all 16 transudative processes; the presence of any one of Light's three criteria correctly classified 15 of 17 exudative processes, whereas the absence of all three criteria correctly classified 14 of 16 transudative processes. Clinical judgment and Light's criteria are comparable in their ability to predict whether an exudative or transudative process was responsible for the effusion. Both methods are associated with errors, though of different kinds; these errors occurred infrequently. Recognizing the limitations of these methods will permit the most accurate effusion categorization.

Aged↗

Soluble leukocyte selectin in the analysis of pleural effusions.

STUDY OBJECTIVES: To determine if soluble leukocyte selectin (sL-selectin) levels in serum and pleural fluid (PF) are an inflammatory marker that differentiates pleural effusion transudates from exudates. DESIGN: sL-selectin PF and serum levels were measured in consecutive patients and compared to established criteria. SETTING: A tertiary-care military medical center. PATIENTS: One hundred twenty patients undergoing diagnostic or therapeutic thoracentesis. INTERVENTIONS: PF and serum samples were collected during thoracentesis and analyzed separately for sL-selectin levels. Results were compared with clinical diagnosis and established PF criteria including the criteria of Light et al, cholesterol ratio, total bilirubin ratio, and albumin gradient. MEASUREMENTS AND RESULTS: sL-selectin levels in PF and serum were determined in 109 patients. By clinical diagnosis, mean +/- SD PF sL-selectin levels were 200.2 +/- 124.3 ng/mL in transudates and 496.8 +/- 379.2 ng/mL in exudates (p < 0.001). By the criteria of Light et al, mean PF sL-selectin levels were 195.7 +/- 105.2 ng/mL in transudates and 448.2 +/- 367.6 ng/mL in exudates (p < 0.001). Mean sL-selectin PF to serum ratios were 0.31 +/- 0.17 in transudates and 0.72 +/- 0.31 in exudates (p < 0.001) by clinical criteria, and 0.31 +/- 0.18 in transudates and 0.64 +/- 0.33 in exudates (p < 0.001) by the criteria of Light et al. No significant difference was noted with serum sL-selectin levels between groups. CONCLUSIONS: sL-selectin is an inflammatory marker that differentiates transudates from exudates in pleural effusions and is a sensitive indicator for PF analysis.

Biomarkers↗

[Pleural diseases: an unusual cause of cough].

The parietal pleura contains myelinated sensitive nerve fibers as well as mechanoreceptors which coordinate the breathing muscles. The small volume of fluid within the pleural space is in dynamic balance: hydrostatic and colloid-osmotic pressures maintain a constant flow of fluid from the parietal to the visceral pleura, which turns into pleural effusion under pathological conditions. Separation of transudate from exudate is best done by calculation of the protein and LDH ratios in the pleural fluid and in serum. Transudates of cardiac origin are due to congestive left heart failure alone. In detecting subpulmonary pleural effusion, ultrasonography is more accurate than X-ray in lateral decubitus. Pleural exudate is investigated by chemical, microbiological and cytological examination of the fluid, complemented by pleural biopsy, fibre bronchoscopy and thoracoscopy. In this way less than 10% of pleural effusions remain unexplained.

Cough↗

[Kinin system components, free kinins and proteinase inhibitors in the edematous fluids of nephrotic syndrome patients].

Main components of the kinin system, free kinins, total arginine esterase activity content of alpha 1-antitrypsin and alpha 2-macroglobulin fractions were estimated in various edematous fluids (transduates of different localization, pleural exudates of the inflammatory type) of patients with nephrotic syndrome of various etiology. Noninflammatory edematous fluids (interstitial, abdominal and pleural transudates) were found to contain activated kallikrein and prekallikrein from blood plasma; 3-10 ng/ml of free kinins were present in interstitial edematous fluids and 30-60 ng/ml - in abdominal transudate. Kinins of abdominal transudate were identified with bradikinin by chromatographic properties; a single low-molecular form of kininogene was found, its content did not exceed 10% of the substance occurring in blood plasma of the patients. These edematous fluids practically did not exhibit the kininase activity and contained unsignificant amounts of proteinase inhibitors. Pleural exdates of the inflammatory type were distinctly different from transudates in content of the kinin system components. Depending on the higher content of protein (2.5% as compared with 0.3-0.7% in transudates) the exudates contained high-molecular kininogene and kininase I. Relative content of kallikrein in pleural exudates was lower and that of prekallikrein - higher as compared with transudates; acid kininogenases were not observed. Free kinins (30 ng/ml) were found in three samples of pleural exudates out of five samples studied. The inflammatory type of pleural exudates correlated with the high level of alpha 1-antitrypsin. As shown by comparative analysis of protein fractions from edematous fluids and corresponding samples of blood plasma of patients with nephrotic syndrome, diffusion is the main reason, which determines the course of protein transition from inter-into exovasal space, under conditions of increased vascular permeability. Kallikrein activation and extravasal formation of bradikinin were apparently the long-term affecting factors, supporting the state of increased vascular permeability in nephrotic syndrome; they had an aggravating role in pathogenesis of refractory nephrotic edema, nephrotic crises and cutaneous erythema.

Adolescent↗

Diagnostic value of ferritin, haptoglobin, alpha 1-antitrypsin, lactate dehydrogenase and complement factors C3 and C4 in pleural effusion differentiation.

Searching to define diagnostic criteria for malignant and non-malignant pleural effusions, the differential diagnostic value of ferritin (FRT), haptoglobin (Hp), alpha 1-antitrypsin (alpha 1-AT), lactate dehydrogenase (LDH) and complement factors C3 and C4 were investigated prospectively in 100 consecutive patients with pleural effusions of various aetiologies. Pleural effusion FRT, C3 and C4 concentrations were found to be useful in differentiating exudates from transudates, so that transudates practically could be excluded in pleural effusion: serum FRT ratio lower than 0.5 and/or in pleural effusion values for C3 and C4 higher than 300 mg dl-1 and 70 mg dl-1, respectively. A pleural effusion: serum C3 ratio greater than 2 is seen only in malignant effusions. No discriminative pleural: serum ratio could be found in FRT and C4 values capable of differentiating malignant from non-malignant effusions. Pleural effusion alpha 1-AT and LDH values were elevated in exudates, as compared with transudates, and had an excellent sensitivity and predictive value, but low specificity, in differentiating malignant from non-malignant effusions. Finally, the sensitivity, specificity and positive predictive value of pleural effusion Hp concentrations were lower than those of FRT and complement factors C3 and C4, respectively.

Adult↗

Is albumin gradient or fluid to serum albumin ratio better than the pleural fluid lactate dehydroginase in the diagnostic of separation of pleural effusion?

BACKGROUND: To determine the accuracy of serum-effusion albumin gradient (SEAG) and pleural fluid to serum albumin ratio (ALBR) in the diagnostic separation of pleural effusion into transudate and exudate and to compare SEAG and ALBR with pleural fluid LDH (FLDH) the most widely used test. METHODS: Data collected from 200 consecutive patients with a known cause of pleural effusion in a United Kingdom district general hospital. RESULTS: The median and inter quartile ranges (IQR) for SEAG 93.5 (33.8 to 122.5) g/dl, ALBR 0.49 (0.42 to 0.62) and FLDH 98.5 IU/L(76.8 to 127.5) in transudates were significantly lower than the corresponding values for exudates 308.5 (171 to 692), 0.77 (0.63 to 0.85), 344 (216 to 695) all p < 0.0001. The Area Under the Curve (AUC) with 95% confidence intervals (Cl) for SEAG, ALBR and FLDH were 0.81 (0.75 to 0.87), 0.79 (0.72 to 0.86) and 0.9 (0.87 to 0.96) respectively. The positive likelihood ratios with 95%CI for FLDH, SEAG, and ALBR were: 7.3(3.5-17), 6.3(3-15) 6.2(3-14) respectively. There was a significant negative correlation between SEAG and ALBR (r= -0.89, p < 0.0001). CONCLUSION: The discriminative value for SEAG and ALBR appears to be similar in the diagnostic separation of transudates and exudates. FLDH is a superior test compared to SEAG and ALBR.

Journal Article↗

Comparison of the anti-inflammatory actions of flunixin and ketoprofen in horses applying PK/PD modelling.

A comparative study in horses of the pharmacokinetics (PK) and pharmacodynamics (PD) of 2 extensively used nonsteroidal anti-inflammatory drugs (NSAIDs), flunixin (FXN) and ketoprofen (KTP), was carried out applying PK/PD modelling. To evaluate the anti-inflammatory properties of these drugs a model of acute inflammation, comprising surgically implanted subcutaneous tissue cages stimulated by intracaveal injection of carrageenan, was used. FXN elimination half-life (T1/2 beta) in plasma was 3.37 +/- 1.09 h. However, in exudate a much longer T1/2 beta was obtained (15.99 +/- 3.80 h). Apparent volume of distribution (Vdarea) for FXN was 0.317 +/- 0.126 l/kg and body clearance (ClB) was 0.058 +/- 0.004 l/kg/h. KTP displayed enantioselective pharmacokinetics, the S(+) enantiomer being predominant in plasma, exudate and transudate. T1/2 beta values for R(-) and S(+)KTP were, respectively, 1.09 +/- 0.19 h and 1.51 +/- 0.45 h (plasma) and 19.73 +/- 2.72 h and 22.64 +/- 4.34 h (exudate), respectively. R(-)KTP was cleared more rapidly than the S(+) enantiomer. ClB values were 0.277 +/- 0.035 l/kg/h and 0.202 +/- 0.022 l/kg/h, respectively. FXN and KTP pharmacodynamics was evaluated by determining their inhibitory effects on serum thromboxane (Tx)B2, exudate prostaglandin (PG)E2, leukotriene (LT)B4 and beta-glucuronidase (beta-glu) and intradermal bradykinin-induced swelling. Both drugs produced marked inhibition of serum TxB2 synthesis for up to 24 h, with no significant differences between the drugs. FXN was a more potent inhibitor of exudate PGE2, the EC50 for FXN being lower (P < 0.01) than that for KTP (0.019 +/- 0.010 microgram/ml and 0.057 +/- 0.009 microgram/ml, respectively). Neither drug had any effect on exudate LTB4 concentration. Differences between the 2 drugs were observed for the inhibition of beta-glu, the Emax for KTP being higher (P < 0.01) than for FXN. However, no differences were observed in other PD parameters. Both FXN and KTP inhibited bradykinin-induced swelling. Differences between the drugs were obtained for Emax, which was greater for FXN (P < 0.01) than for KTP. Equilibration half-life (T1/2Ke0) also differed, being much longer (P < 0.01) for FXN than for KTP. PK/PD modelling proved to be a useful and novel analytical technique for studying the pharmacodynamics of NSAIDs, with the advantage over classical in vitro methods that it provides data in the whole animal. By quantifying action-concentration interrelationships through PK-PD modelling, it is possible to shed light on molecular mechanisms of drug action, and establish probable differences in mechanisms of action between structurally similar drugs.(ABSTRACT TRUNCATED AT 400 WORDS)

Acute Disease↗

Bayesian analysis using continuous likelihood ratios for identifying pleural exudates.

STUDY OBJECTIVES: To ascertain if equations that calculate continuous likelihood ratios (CLRs) for pleural exudates improve pleural fluid categorization, especially when false positive or false negative test results are obtained by using Light's criteria. DESIGN AND SETTING: Retrospective review of the clinical and pleural fluid data from a consecutive series of patients with pleural effusion who underwent thoracentesis at the University Hospital Arnau de Vilanova (Lleida, Spain) over an 11-year period. PATIENTS AND METHODS: A total of 1490 patients with pleural effusion (298 transudates and 1192 exudates) were recruited into the study. The presence of a transudate or exudate was established by clinical judgment. We examined the comparative diagnostic accuracy of 4 tests (i.e. pleural fluid protein and lactate dehydrogenase (LDH), and pleural fluid to serum protein and LDH ratios) for discriminating between transudates and exudates. Decision thresholds were determined by receiver operating characteristics (ROC) analysis. Equations for calculating CLRs derived from a logistic regression analysis based on a previously described method. RESULTS: Individual pleural fluid tests did not differ in their diagnostic accuracies according to ROC analysis. We calculated CLRs for the elements of Light's criteria and pleural fluid protein, and also illustrated the sequential use of CLRs for determining posttest probabilities. Overall, CLR formulas had marginal performance for the correct categorization of pleural fluid. CONCLUSIONS: CLRs provide a probabilistic statement as to the likelihood an effusion is a transudate or exudate. However, clinical judgment is little changed by the application of CLRs, and in doubtful cases a great amount of uncertainty remains. This Bayesian approach is likely to have no major impact on the clinical practice.

Bayes Theorem↗

[Apolipoprotein A1 and apolipoprotein B in pleural effusions].

OBJECTIVE: To determine the levels of apolipoprotein A1 and apolipoprotein B in pleural effusions and analyze their possible diagnostic value. PATIENTS AND METHODS: A total of 117 patients with pleural effusion (30 transudates and 87 exudates) were included. The apolipoproteins were measured by turbidimetry. RESULTS: The apolipoprotein B values in serum were slightly lower in transudates than in exudates, and both apolipoproteins had lower values in patients with benign exudates than in malignant ones. The apolipoprotein levels in pleural fluid were lower in transudates than in exudates. The pleural/serum fluid ratios of both apolipoproteins were significantly lower in malignant effusions compared with benign exudates. No cutoff value was found that would make it possible to differentiate between transudates and exudates or between benign and malignant exudates with sensitivity or specificity levels that had clinical interest. CONCLUSIONS: Apolipoprotein A1 and apolipoprotein B levels in pleural fluid are different in transudates and exudates, and the pleural/serum fluid ratios are also different between benign and malignant exudates. However, their measurement does not supply additional clinical information.

Apolipoproteins A↗

Pleural effusions in the intensive care unit.

The incidence of pleural effusions in the intensive care unit varies depending on the screening methods, from approximately 8% for physical examination to more than 60% for routine ultrasonography. Several factors contribute to the occurrence of pleural effusions in intensive care unit patients: large amounts of intravenous fluid are often administered, pneumonia is common, and heart failure, atelectasis, extravascular catheter migration, hypoalbuminemia, or liver disease are present in many intensive care unit patients. In surgical intensive care units, cardiac or abdominal surgery is often followed by pleural effusions, and in trauma patients, hemothorax is a dreaded event. Because no clinical parameter excludes pleural infection, and because of the impact of thoracentesis on diagnosis and treatment, this procedure should be performed unless contraindicated. Thoracentesis is safe in mechanically ventilated patients. The author discusses the following points regarding pleural effusions in the intensive care unit: screening intensive care unit patients for pleural effusion, safety of thoracentesis in patients receiving invasive mechanical ventilation, distinguishing exudates from transudates, and diagnosing and managing infected pleural effusions in critically ill patients. Lastly, the author suggests a research agenda for pleural effusions in intensive care unit patients.

Empyema↗

[The diagnostic usefulness of cholinesterase in pleural exudates].

BACKGROUND AND OBJECTIVES: The pleural fluid/serum cholinesterase ratio (PF/S) is the most efficient parameter to differentiate transudates from exudates. The objective of this study was to evaluate whether its determination might yield additional diagnostic information in pleural exudates. MATERIALS AND METHODS: A total of 167 patients with the diagnosis of pleural exudate were studied: 74 carcinomatous, 32 tuberculous, 31 parapneumonic, 30 other causes. Pleural fluids were divided on the basis of lymphocyte or polymorphonuclear predominance and were grouped according to diagnosis. The PF/S cholinesterase ratio was determined in all patient. RESULTS: In lymphocytic exudates, when PF/S ratio was < 0.42 pleural effusion was classified as malignant, with a sensitivity (S) of 56% (95% CI: 43%-66%) and a specificity (SP) of 90% (95% CI: 78%-95%). For the diagnosis of tuberculosis, in the total of pleural effusions, a ratio > or = 0.45 showed a S of 97% (95% CI: 82%-99%) and a SP of 51% (95% CI: 42%-59%). CONCLUSIONS: The PF/S cholinesterase ratio yielded an useful information on the diagnosis of pleural exudates. Thus, in our series of patients, a ratio < 0.42 in a lymphocytic effusion suggested a malignant origin, and a ratio < 0.45 practically ruled out tuberculosis, irrespective of the cellular predominance in the pleural fluid.

Adult↗

Comparative study of biochemical characteristics of the fluids in otitis media with effusion and postoperative maxillary cysts.

The biochemical characteristics and smears of the fluids in M-OME, S-OME, AOM, POMC, and AMS were studied. The fluids in S-OME and POMC had the character of transudate rather than exudate. On the other hand, M-OME, AOM, and AMS showed a more exudative or secretive nature. The character of the product from the inflammatory process of the specific condition was particularly seen in M-OME, AOM, and AMS. Thus we speculate that the chronic inflammatory process has a close relationship to the pathogenesis of OME, especially in mucoid types.

Acute Disease↗

Value of sonography in determining the nature of pleural effusion: analysis of 320 cases.

To assess the value of sonography in determining the nature of pleural effusions, we prospectively analyzed the sonographic findings in 320 patients with pleural effusion of various causes (224 with exudates and 96 with transudates). The nature of the effusions was established on the basis of chemical, bacteriologic, and cytologic examination of pleural fluid; pleural biopsy; and clinical follow-up. All patients had high-frequency, real-time sonography performed by one of three sonographers who had no clinical information concerning the patients. The sonographer evaluated the images for internal echogenicity of the effusion, thickness of the pleura, and associated parenchymal lesions of the lung. The images were also printed out and interpreted a second time by the other two sonographers to reach a consensus. Our results showed that the two types of effusions could be distinguished on the basis of sonographic findings. Transudates were anechoic, whereas an anechoic effusion could be either a transudate or an exudate. Pleural effusions with complex septated, complex nonseptated, or homogeneously echogenic patterns were always exudates (p less than .01). Sonographic findings of thickened pleura and associated parenchymal lesions in the lung also were indicative of an exudate (p less than .01). Homogenous echogenic effusions were due to hemorrhagic effusion or empyema. Sonographic evidence of a pleural nodule was a specific finding in patients with a malignant effusion. We conclude that sonography is useful in determining the nature of pleural effusion.

Adolescent↗

[The findings and value of computed tomography in pleural empyema].

Chest radiographs and CT images of 25 patients with pleural empyemas were compared retrospectively with those of 20 patients with pleural exudates and transudates in order to determine criteria for differential diagnosis and to define the place of CT in the diagnosis of pleural empyemas. The sign which was most suggestive of an empyema on a chest radiograph was an encapsulated effusion in an atypical position (18/25); this was found in only 4 out of 20 exudates and in none of the transudates. On CT, changes in the pleura, the subcostal tissues and the configuration and position of the fluid were suggestive of an empyema. In nearly all patients with a pleural empyema there was thickening and increased contrast uptake of the parietal pleura (22/25) and thickening and increased density oft the subcostal tissues (23/25). Usually, empyemas were encapsulated and biconvex (20/25). None of the patients with pleural transudates showed any of these changes. In the presence of some pleural exudates, pleural (14/20) or thoracic (11/20) changes were noted. In part, these changes were due to previous treatment (sclerotherapy) or tumour infiltration (7/20). An attempt to correlate the CT findings with changes in the pleura and subcostal tissues with the clinical empyema stages I-III, according to Light, showed that CT was unable to distinguish between early and late empyemas. Consequently, diagnostic aspiration remains necessary for correct treatment.

Adult↗

[VEGF (vascular endothelial growth factor) concentration in serum and pleural fluid of patients with pleural malignancy and pleural tuberculosis].

The purpose of this study was comparison of VEGF (vascular endothelial growth factor) levels in serum and pleural fluid and estimation of this test usefulness in diagnosis of pleural effusions. VEGF levels were measured by ELISA method in 68 patients (45 males and 23 females) aged 19-81 years. By Light's criteria in 16 cases transudate and in 52 cases exudate was recognized. By means of fluid cytology, pleural biopsy, microbiology or thoracoscopy in 10 cases pleural metastases from distant organs, in 15 cases coexisting pulmonary neoplasm, in 11 cases mesothelioma and in 16 cases tuberculosis were determined as a cause of fluid accumulation in pleural space. The mean VEGF levels were significantly higher (p < 0.001) in patients with exudates than in patients with transudates (3833 pg/ml and 325 pg/ml respectively). Based on likelihood ratios analysis, as a cut off value in differentiation of exudates and transudates a value 700 pg/ml was accepted. The sensitivity of this test was 75% and the specificity 93% and likelihood ratio (LR) 12.5. The mean VEGF level in exudates was seven times higher than mean VEGF level in serum (3833 pg/ml and 573 pg/ml respectively). Mean VEGF levels in malignant exudates (4615 pg/ml) were significantly higher than in tuberculous exudates (2073 pg/ml). As a cut off value in differentiation between malignant and tuberculous exudates a value of 4500 pg/ml was accepted. We conclude that our results suggests the local VEGF production in pleural cavity and the significant role of this cytokine in pleural exudates accumulations and also suggests the usefulness of VEGF estimation in pleural fluid in differentiation transudates from exudates and malignant from tuberculous pleural fluids.

Adult↗

Treatment of congestive heart failure. Its effect on pleural fluid chemistry.

The proper classification of pleural effusions into transudates and exudates has great clinical significance. It is believed that the treatment of congestive heart failure may convert an associated transudative pleural effusion into a "pseudoexudate." We studied eight patients with congestive heart failure during nine episodes of decompensation with pleural effusion, which was bilateral in five and right-sided in three. Thoracocentesis was done on identification of the patient and at 6 +/- 2 days after treatment of heart failure resulting in diuresis and a mean weight loss of 5.8 +/- 3.2 kg. The mean protein level of the pleural fluid was 2.2 +/- 0.7 g/dL at the initial study and increased to 3.2 +/- 1.08 g/dL at the final study (p less than 0.01). The LDH level of the pleural fluid increased from 116 +/- 69 to 183 +/- 117 units/L (p less than 0.01). The fluid/serum ratio for protein increased from 0.34 +/- 0.09 to 0.47 +/- 0.13 (p less than 0.01) and for LDH from 0.39 +/- 0.16 to 0.64 +/- 0.28 (p less than 0.01). In three patients, pleural fluid was classified as a transudate at the initial study but met the criteria for an exudate after treatment of heart failure. Effectiveness of diuresis was measured by weight loss; a significant correlation between weight loss per day and change in the protein level of the pleural fluid was noted (r = 0.715; p less than 0.05). We conclude that the treatment of congestive heart failure causes significant changes in the pleural fluid's chemistry; in some cases, a transudate may be converted into a "pseudoexudate."

Aged↗