Pleural fluid tumour markers in malignant pleural effusion with inconclusive cytologic results.

BACKGROUND: The presence of tumour cells in pleural fluid or tissue defines an effusion as malignant. Cytology analysis of the pleural fluid has about 60% diagnostic sensitivity. Several tests have been proposed to improve diagnosis-among them, the concentrations of tumour markers in pleural fluid. We evaluated whether the concentrations of tumour markers in pleural fluid could improve the diagnosis of malignant pleural effusion (mpe) when cytology is doubtful. METHODS: Lymphocytic pleural fluids secondary to tuberculosis or malignancy from 156 outpatients were submitted for cytology and tumour marker quantification [carcinoembryonic antigen (cea), cancer antigen 15-3 (ca15-3), carbohydrate antigen 19-9 (ca19-9), cancer antigen 72-4 (ca72-4), cancer antigen 125 (ca125), and cyfra 21-1). Oneway analysis of variance, the Student t-test or Mann-Whitney test, and receiver operating characteristic curves were used in the statistical analysis. RESULTS: Concentrations of the tumour markers cea, ca15-3, ca125, and cyfra 21-1 were higher in mpes than they were in the benign effusions (p < 0.001), regardless of cytology results. The markers ca19-9 and ca72-4 did not discriminate malignant from benign effusions. When comparing the concentrations of tumour markers in mpes having positive, suspicious, or negative cytology with concentrations in benign effusions, we observed higher levels of cea, ca15-3, cyfra 21-1, and ca125 in malignant effusions with positive cytology (p = 0.003, p = 0.001, p = 0.002, and p = 0.001 respectively). In pleural fluid, only ca125 was higher in mpes with suspicious or negative cytology (p = 0.001) than in benign effusions. CONCLUSIONS: Given high specificity and a sensitivity of about 60%, the concentrations of tumour markers in pleural effusions could be evaluated in cases of inconclusive cytology in patients with a high pre-test chance of malignancy or a history of cancer.

Effect of temperature and storage time on cellular analysis of fresh pleural fluid samples.

OBJECTIVE: Despite the methodological variability in preparation techniques for pleural fluid cytology, it is fundamental that the cells should be preserved, permitting adequate morphological classification. We evaluated numerical and morphological changes in pleural fluid specimens processed after storage at room temperature or under refrigeration. METHODS: Aliquots of pleural fluid from 30 patients, collected in ethylenediaminetetraacetic acid-coated tubes and maintained at room temperature (21 °C) or refrigeration (4 °C) were evaluated after 2 and 6 hours and 1, 2, 3, 4, 7 and 14 days. Evaluation of cytomorphology and global and percentage counts of leucocytes, macrophages and mesothelial cells were included. RESULTS: The samples had quantitative cellular variations from day 3 or 4 onwards, depending on the storage conditions. Morphological alterations occurred earlier in samples maintained at room temperature (day 2) than in those under refrigeration (day 4). CONCLUSIONS: This study confirms that storage time and temperature are potential pre-analytical causes of error in pleural fluid cytology.

Acute inflammatory response secondary to intrapleural administration of two types of talc.

Intrapleural instillation of talc has been used in the treatment of recurrent pleural effusions but can, in rare instances, result in respiratory failure. Side-effects seem to be related to composition, size and inflammatory power of talc particles. The aim of this study was to evaluate the inflammatory response to intrapleural injection of talc containing small particles (ST) or talc containing particles of mixed size (MT). 100 rabbits received intrapleural talc, 50 with ST (median 6.41 mum) and 50 with MT (median 21.15 mum); the control group was composed of 35 rabbits. Cells, lactate dehydrogenase, C-reactive protein (CRP), interleukin (IL)-8 and vascular endothelial growth factor were evaluated in serum and bronchoalveolar lavage at 6, 24, 48, 72 and 96 h. Lung histology and the presence of talc were also analysed. Statistics were performed using ANOVA and an unpaired t-test. Most of the parameters showed greater levels in the animals injected with talc than in the controls, suggesting a systemic and pulmonary response. Higher serum levels of CRP and IL-8 were observed in the animals injected with ST. Talc particles were observed in both lungs with no differences between groups. Lung cell infiltrate was more evident in the ST group. In conclusion, talc with larger particles should be the preferred choice in clinical practice in order to induce safer pleurodesis.

Influence of atelectasis on pulmonary function after coronary artery bypass grafting.

The purpose of this study was to determine the influence of atelectasis on pulmonary function 6 days following coronary artery bypass grafting (CABG). After 6 days, 30 patients had normal chest radiographs, 38 had atelectasis, and 57 had pleural changes. In 11 patients, atelectasis only was observed in the radiograph, and in 27 it was in combination with pleural changes. The decrease in FVC and FEV1 in the patients with atelectasis was 33.4 and 33.5 percent in the SVG group and 34.8 and 34.3 percent in the IMA group, while in those patients with a normal radiograph, the decrements were 26.3 and 26.9 percent in SVG group and 26.1 and 26.9 percent in IMA group, respectively. Thus, patients with atelectasis on the 6th postoperative day have a larger decrement in pulmonary function post CABG than the patients with normal chest radiograph and this reduction reflects a higher degree of thoracic trauma.

Subclinical surface alterations of human pleura. A scanning electron microscopic study.

Pleuritis or pleural effusion frequently develops in patients with pneumonia or heart failure. Most of these pleural changes regress without intrapleural intervention. The detailed mechanisms of the regression of the pleural changes in humans are not well documented. We studied the parietal pleura of nine patients with lung cancer and two patients with coronary artery disease by scanning electron microscopy (SEM). All patients had neither radiographic nor gross evidence of pleural disease but all had mixed surface alterations by SEM. Focal denudation of mesothelial cells was common. Deeper injuries exposed thick and thin interweaving collagen bundles. Patchy depositions of amorphous or crystallized fibrin covered normal and damaged pleural surfaces, frequently admixed with macrophages, red blood cells, and tissue debris. Reactive mesothelial cells appeared to proliferate over the fibrin. Our findings suggest that subclinical pleural alterations occur often in patients with pulmonary or cardiac diseases and that an intact pleural surface in those patients is restored mainly by the proliferation of reactive mesothelial cells.

Comparison of the effectiveness of tetracycline and minocycline as pleural sclerosing agents in rabbits.

Parenteral tetracycline, one of the most commonly used agents for producing pleurodesis, is no longer available because of stricter regulations governing the manufacturing process. The objective of this project was to determine whether minocycline, a tetracycline derivative, is an effective sclerosant in an experimental model in rabbits. We also studied the relationship of the dose and the volume injected to the degree of pleurodesis. The following medications were instilled intrapleurally in anesthetized male rabbits: tetracycline, 35 mg/kg; or minocycline, 4, 7, 10, or 20 mg/kg, diluted to a total volume of 1 or 2 ml of bacteriostatic saline solution; or minocycline, 40 mg/kg, diluted to a total volume of 2 ml of the solution. Twenty-eight days after the instillation, the animals were killed. The pleural spaces were assessed grossly for evidence of pleurodesis and microscopically for evidence of fibrosis and inflammation. The degree of pleurodesis grossly and microscopically after the injection of 7, 10, 20, or 40 mg/kg of minocycline was comparable to that after the injection of 35 mg/kg of tetracycline, while the dose of 4 mg/kg was less effective. In the animals who received the higher doses of minocycline intrapleurally (ie > or = 20 mg/kg), there was an excess mortality both early (chi 2 = 3.61, 0.05 < p < 0.10) and late (chi 2 = 11.0, p < 0.005) which appeared to be related to the development of hemothorax. The intrapleural injection of the tetracycline derivatives was significantly (p < 0.05) more effective when the total volume of the solution was 2 ml rather than 1 ml. The present study demonstrates that minocycline is an effective agent for producing pleurodesis in the rabbit. Minocycline given intrapleurally at doses of 7 mg/kg or above is comparable to tetracycline, 35 mg/kg. Higher doses of minocycline (> or = 20 mg/kg) produce a high mortality that seems to be related to hemothorax. Since, in humans, a large experience confirms only 20 mg/kg of tetracycline is needed to produce adequate pleurodesis safely, we recommend a dose of 4 mg/kg of minocycline for the production of pleurodesis.

Intrapleural talc for the prevention of recurrence in benign or undiagnosed pleural effusions.

Chemical pleurodesis has become the preferred treatment for definitive management of malignant pleural effusions. The treatment of patients with recurrent benign or undiagnosed pleural effusions, however, remains a difficult clinical problem. Tetracycline has been widely used as a sclerosing agent, but parenteral tetracycline is no longer available. Therefore, alternative sclerosing agents are needed. Talc was used for the first time in 1935, and subsequently there have been several reports documenting its effectiveness in the treatment of malignant pleural effusion and pneumothorax. The objective of this study is to present our experience with a low dose of aerosolized talc for controlling nonmalignant pleural effusions. Between May 1985 and October 1992, twenty-two patients underwent talc pleurodesis at the time of thoracoscopy for control of a nonmalignant effusion. The cause of the effusion was cirrhosis in six patients, systemic lupus erythematosus in two, chylothorax in five, and no diagnosis in nine patients. Follow-up has ranged from 18 days to 5 years. Only two patients (9 percent), one with cirrhosis and another with an undiagnosed pleural effusion, had a recurrence of the effusions. We conclude that the intrapleural administration of 2 g of aerosolized talc is an effective treatment for recurrent benign (including chylothorax) or undiagnosed pleural effusions.

Intrapleural talc for the prevention of recurrent pneumothorax.

The ipsilateral recurrence rate after the first spontaneous pneumothorax treated with tube thoracostomy is reported to be between 23 percent and 52 percent. The incidence of recurrence after the first recurrence is substantially higher. Chemical pleurodesis has been attempted to decrease the recurrence rate. Tetracycline has been widely utilized, but parenteral tetracycline is no longer available. Therefore, alternative sclerosing agents have been used. Talc has been demonstrated to be effective in preventing recurrences and it has minimal long-term effects. This prospective study was designed to determine the efficacy of talc pleurodesis in patients with recurrent spontaneous pneumothorax. Eighteen patients admitted between May 1985 and March 1993 to the Department of Thoracic Surgery underwent thoracoscopy and were treated by tube thoracostomy with chemical pleurodesis. All the patients had had at least two pneumothoraces and six had had at least six pneumothoraces. Sterile asbestos-free talc, 2g, was aerosolized throughout the pleural surface. One or two chest tubes were inserted, left clamped for 2 h, and unclamped after this time. The tubes were removed when no air had escaped for 24 h. Only one (5.6 percent) patient had recurrence of the pneumothorax, and a second insufflation of talc resulted in no new recurrence after a follow-up of 10 months. The remaining 94.4 percent did not have recurrence of pneumothorax within an observation period of 38.5 +/- 28.1 months. The follow-up was more than 2 years for 66.7 percent with no recurrence and was more than 5 years for 33.3 percent. We conclude from these observations that the insufflation of 2 g of talc into the pleural space is a safe effective treatment for control of recurrent spontaneous pneumothorax.

Effect of inhaled furosemide on the bronchial response to lysine-aspirin inhalation in asthmatic subjects.

It has been demonstrated recently that inhaled furosemide inhibits bronchoconstriction induced by cold air, physical exercise, various antigens, and metabisulfite. The goal of the present study was to determine if the inhalation of furosemide would inhibit the bronchoconstriction resulting from the inhalation of lysine-aspirin in aspirin-sensitive asthmatics. Six female subjects with known hypersensitivity to aspirin participated in this crossover study comparing 20 mg of inhaled furosemide and placebo. The volunteers inhaled increasing concentrations of lysine-aspirin after the inhalation of furosemide or placebo. The geometric mean provocative dose causing a 20 percent decrease in the FEV1 (PD20) after the inhalation of placebo was 30.4 mg/ml and the PD20 was equal or below 90 mg/ml in all patients. In contrast, the FEV1 did not decrease by 20 percent in any of the patients pretreated with furosemide when the inhaled concentration was increased to 360 mg/ml. From this study, we conclude that the administration of furosemide blocks the bronchospasm induced by the inhalation of lysine-aspirin in aspirin-sensitive asthmatics.

Relationship between pleural changes after myocardial revascularization and pulmonary mechanics.

It is known that coronary artery bypass grafting (CABG) results in impairment of postoperative pulmonary function. There is also a high incidence of pleural changes (pleural effusion or pleural thickening) after CABG. We hypothesized that those patients with pleural changes in the postoperative period would have a greater decrease in pulmonary function test (PFTs) results. The present study reports the results of 110 male patients who underwent CABG. The chest films and the PFT results obtained preoperatively and on the sixth postoperative day were reviewed. The relationship between pleural changes and PFTs was analyzed in patients who received saphenous vein graft alone (SVG group: 50 patients) or in combination with internal mammary artery grafting (IMA group: 60 patients). In the IMA group, the patients who had pleural changes had significantly greater decreases in their pulmonary function than did the patients without pleural changes. The decrease in the FVC, TLC and FEV1 in the patients with pleural effusions (37.6, 27.8 and 36.8 percent) was similar to that in patients with pleural thickening (34.6, 28.3 and 35.0 percent) and both were significantly greater (p < 0.05) than the changes in the patients with a normal radiograph (26.1, 17.6 and 26.9 percent). In the SVG group, the presence of pleural changes was not significantly related to the decrement in pulmonary function. The values of RV, FRC, Cst, and blood gases were not affected in the SVG or IMA group by the presence of pleural changes. We conclude that the presence of pleural changes on the chest radiograph is associated with a larger decrement of pulmonary function after CABG in the IMA group. This larger decrease probably reflects added thoracic trauma and is not due to the presence of pleural changes per se.

High-resolution CT scan in the evaluation of exercise-induced interstitial pulmonary edema in cardiac patients.

OBJECTIVE: To evaluate the onset of exercise-induced interstitial pulmonary edema in cardiac patients by high-resolution CT (HRCT). DESIGN: Prospective, normal controlled. PARTICIPANTS: Thirty subjects divided into three groups: group 1--10 outpatients with chronic congestive heart failure (CCHF), New York Heart Association (NYHA) class I; group 2--10 outpatients with CCHF, NYHA class II/III; and group 3 (control)--10 normal subjects. METHOD: HRCT scans were obtained at rest and 4, 8, 12, 16, and 20 min after progressive treadmill exercise test. RESULTS: The following HRCT findings consistent with interstitial edema were significantly different (p<0.05) in group 2 when compared with groups 1 and 3: artery/bronchus ratio > 1 in the upper lobes, peripheral increase in the vascular markings, interlobular septal thickening, and peribronchial "cuffing." These differences were maximal at 12 min after exercise and returned to normal values after 20 min. CONCLUSION: Interstitial pulmonary edema was present immediately after exercise in CCHF patients. It may be important in the genesis of dyspnea of these patients.

Scimitar sign with normal pulmonary venous drainage and systemic arterial supply. Scimitar syndrome or bronchopulmonary sequestration?

The classic definition of the scimitar syndrome is a triad of hypoplasia of the right lung with anomalous venous drainage and a systemic arterial supply of a variable degree. We report a case in which a scimitar-shaped anomalous vein was observed on the plain chest radiograph, but subsequently a pulmonary angiogram showed that it drained normally into the left atrium.

Relationship between pleural effusion and pericardial involvement after myocardial revascularization.

The explanation for the high incidence of pleural effusion after cardiac surgery is unclear. There is a high incidence of left pleural effusion with inflammatory pericardial disease. We hypothesized that after coronary artery bypass grafting (CABG) there would be a higher incidence of pleural effusions in patients with pericardial involvement. We prospectively studied 47 patients undergoing elective CABG; 17 had only saphenous vein grafts (SVG group) and 30 received at least one internal mammary artery graft (IMA group) in addition to SVG. Patients had a chest radiograph, chest ultrasound, and an echocardiogram on the 7th, 14th, and 30th postoperative days. Seven days after the surgery, 42 to 47 patients (89.4 percent) had a pleural effusion and 36 (76.6 76.6 percent) pericardial involvement. No relationship was found between the presence of a pleural effusion and a pericardial effusion (p > 0.05). On the 14th postoperative day, 36 patients (76.6 percent) had a pleural effusion while 33 patients (70.2 percent) had a pericardial effusion. There was a significant relationship between the presence of a pleural effusion and a pericardial effusion (p < 0.05). On the 30th postoperative day, 27 patients (57.4 percent) had a pleural effusion and 25 (53.2 percent) had a pericardial effusion. Again, there was a significant relationship between a pleural effusion and a pericardial effusion (p < 0.05). Finally, there was no relationship between the ejection fraction and the presence of pleural effusion at any time (p > 0.05). From this study, we conclude that there is a high prevalence of both pleural and pericardial effusion postoperatively in patients undergoing CABG. Both types of effusions tend to be asymptomatic, gradually disappear, and are more common in the IMA group. Patients who have a persistent pericardial effusion are more likely to have a persistent pleural effusion.

Comparison of silver nitrate and tetracycline as pleural sclerosing agents in rabbits.

The ideal agent to produce pleurodesis has not been identified. Tetracycline, the drug used most commonly in the 1980s, is no longer available. Talc either aerosolized or in a slurry is the agent used just most commonly at the present time, but there are concerns about its safety. Another possibility is silver nitrate, which was widely used in the past, but was abandoned on account of side effects. We hypothesized that lower concentrations of silver nitrate than had been used in the past would be effective in creating a pleurodesis in rabbits. The following medications in a total volume of 2 mL were instilled intrapleurally in three groups of ten anesthetized rabbits: 0.25% or 0.50% silver nitrate and 35 mg/kg tetracycline. Twenty-eight days after the injection, the animals were sacrificed and the pleural spaces were assessed grossly for evidence of pleurodesis and microscopically for evidence of fibrosis and inflammation. The intrapleural injection of 0.50% silver nitrate produced an effective pleurodesis. The mean degree of gross pleurodesis in the rabbits that received 0.50% silver nitrate (3.4 +/- 1.2) did not differ significantly from that of the rabbits that received tetracycline (3.5 +/- 0.7) (scale 0 to 4). The mean degree of microscopic pleural fibrosis in the rabbits that received 0.50% silver nitrate (3.4 +/- 0.7) did not differ significantly from that of the rabbits that received tetracycline (3.9 +/- 0.3). However, 0.25% silver nitrate was ineffective in creating pleural fibrosis, either grossly or microscopically. No rabbits died after the intrapleural injection of the drugs. There were no observed side effects after the injection of silver nitrate. The present study demonstrates that 0.50% silver nitrate instilled into the pleural space is an effective agent for producing pleurodesis in the rabbit; its effect is comparable to tetracycline 35 mg/kg. This agent should be compared with tetracycline derivatives and talc in studies in humans.

Talc slurry is an effective pleural sclerosant in rabbits.

Insufflated talc is probably the most effective agent for creating a pleurodesis both in the clinical situation and in animals. However, the insufflation of talc requires an invasive procedure such as thoracoscopy or thoracotomy. Recently, there have been reports that talc in a slurry was effective in the clinical situation. The objective of this project was to determine whether talc in a slurry at varying doses is an effective sclerosant in an experimental model in rabbits. Talc, 50, 100, 200, and 400 mg/kg, in a 2-mL slurry was injected intrapleurally through a small catheter in male rabbits. Eleven rabbits received each dose. Twenty-eight days after the instillation, the animals were killed. The pleural spaces were assessed grossly for evidence of pleurodesis and microscopically for evidence of fibrosis and inflammation. The degree of pleurodesis (on a scale of 0 to 4) after the injection of 50, 100, 200, and 400 mg/kg of talc was 1.1 +/- 0.9, 1.5 +/- 1.1, 2.7 +/- 0.6, and 3.4 +/- 0.5, respectively. The degree of microscopic fibrosis similarly increased with increasing doses of talc. These scores were similar to those we have reported with the tetracycline derivatives. In contrast to the results with tetracycline derivatives, none of the rabbits developed fibrothorax or hemothorax. From this study, we conclude that talc in a slurry is a very effective pleural sclerosant in rabbits and does not produce hemothoraces as do the tetracycline derivatives.

Effectiveness of bleomycin in comparison to tetracycline as pleural sclerosing agent in rabbits.

The two agents most commonly used for producing a pleurodesis are tetracycline and bleomycin. Tetracycline is no longer available due to more stringent requirements on the manufacturing process. The objective of this project was to determine whether bleomycin is an effective sclerosant in an experimental model in rabbits. The following medications were instilled intrapleurally in anesthetized male rabbits: tetracycline, 35 mg/kg, or bleomycin, 1.5 or 3.0 IU/kg diluted to a total volume of 1 ml with bacteriostatic saline solution. Twenty-eight days after the instillation, the animals were killed, and the pleural spaces were assessed grossly for evidence of pleurodesis and microscopically for evidence of fibrosis and inflammation. The intrapleural injection of bleomycin was ineffective in creating pleural fibrosis, either grossly or microscopically. The mean degree of gross pleurodesis in the six rabbits who received tetracycline was 2.7 +/- 1.5 (scale 0 to 4), while that in the rabbits who received the highest dose of bleomycin was 0.0 +/- 0.0. Based on this study, we recommend that bleomycin not be used as a pleural sclerosant in patients with nonneoplastic pleural disease, eg, those with pneumothorax, congestive heart failure or cirrhosis, and pleural effusion.

Distribution of pleural injectate. Effect of volume of injectate and animal rotation.

It is controversial whether rotation is necessary for patients undergoing pleurodesis. In addition, the optimal volume of the injectate remains to be determined. The purpose of this study was to determine the importance of rotation and the volume of the agent on the intrapleural dispersion of agents injected into the pleural space of rabbits. Technetium 99m pertechnetate (99mTc) in 0.5, 1.0, or 2.0 ml of saline solution was injected into ten lightly anesthetized rabbits, half of whom were rotated for 1 min after the injection. Static images were obtained in the anterior projection 1 and 5 min after the injection. After the second scan, the limits of the lung were defined by obtaining a perfusion scan immediately after the intravenous injection of macroaggregates of 99mTc-labeled serum albumin. The degree of dispersion was significantly greater in the nonrotated groups both at 1 min (F = 8.11, p = 0.0085) and at 5 min (F = 5.89, p = 0.0274). In addition, the homogeneity of the distribution of the injectate was not improved with rotation. From this study, we conclude that rotation of the animal for 1 min after the intrapleural injection does not improve the distribution of the injectate throughout the pleural space. Furthermore, a volume of 0.5 ml is sufficient for all pleural surfaces to be exposed.

Postoperative pleural changes after coronary revascularization. Comparison between saphenous vein and internal mammary artery grafting.

Coronary artery bypass grafting (CABG) is commonly performed with a saphenous vein graft (SVG) and/or an internal mammary artery graft (IMA). We hypothesized that there would be a higher incidence of pleural changes after CABG in patients who underwent IMA grafting because pleurotomy is usually performed. In the present study, the pre and the 6th postoperative day chest roentgenograms of 122 patients who received CABG were reviewed. The incidence of effusion in the patients who received only SVG was 43 percent (23/54) and did not differ significantly (p greater than 0.05) from the incidence in the patients who also had IMA 41 percent (28/68). Almost all of the patients (43/51) had unilateral left-sided pleural effusions. Most of the effusions were small and did not require treatment. The incidence of effusion was not higher in patients with enlargement of their cardiac silhouette or atelectasis and was not related to the presence of chest tubes. The incidence of pleural thickening was higher in the IMA group (49 percent) than in the SVG group (31 percent) but the difference did not achieve statistical significance (p greater than 0.05). We conclude that there is a high (approximately 40 percent) incidence of small effusions and thickening after CABG. The incidence of pleural effusion and pleural thickening do not appear to be influenced by the type of surgery (IMA vs SVG). We speculate that the effusions are due to pericardial inflammation.

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.

Experimental pleurodesis in rabbits induced by silver nitrate or talc: 1-year follow-up.

STUDY OBJECTIVE: To compare the pleurodesis results from the intrapleural injection of silver nitrate and talc slurry over an observation period of 12 months in rabbits. DESIGN: Rabbits were randomized to receive 2 mL of 0.5% silver nitrate or 400 mg/kg of talc slurry in 2 mL intrapleurally. Ten rabbits in each group were killed at 1 month, 2 months, 4 months, 6 months, 8 months, 10 months, and 12 months after intrapleural injection. The degree of gross pleurodesis and the amount of microscopic pleural fibrosis and inflammation were graded on a scale of 0 to 4. RESULTS: The mean +/- SEM gross pleurodesis score in the 70 rabbits that received silver nitrate was 3.34 +/- 0.08, which was significantly higher than the score of 2.32 +/- 0.09 in the 70 rabbits that received talc. The mean gross pleurodesis score was significantly higher at each of the observation times (p < 0.05), except at 2 months, in the rabbits that received silver nitrate. The pleurodesis was distributed throughout the thorax in the rabbits that received silver nitrate, while it was only in the ventral thorax in the rabbits that received talc slurry. The gross pleurodesis scores showed no tendency to decrease during the 12-month observation period in either treatment group. The persistence of talc in the pleural space did not lead to chronic inflammatory changes because the inflammation scores were similar in both groups at all observation times. The microscopic pleural fibrosis score tended to decrease with time in the silver nitrate group but not in the talc slurry group. CONCLUSIONS: The intrapleural injection of 2 mL of 0.5% silver nitrate produces a better pleurodesis than does the intrapleural injection of 400 mg/kg of talc slurry in rabbits. The pleurodesis induced by silver nitrate persists for at least 1 year. The efficacy of silver nitrate as a sclerosing agent in humans should be evaluated.