Mechanisms of pleurodesis

Our plain-English summary of Mechanisms of pleurodesis, by F. Rodriguez-Panadero, A. Montes-Worboys (Respiration; International Review of Thoracic Diseases, 2012).

The study

• Authors: F. Rodriguez-Panadero, A. Montes-Worboys
• Journal: Respiration; International Review of Thoracic Diseases
• Published: 2012;83(2):91-8
• Type of article: Review
• Cited by: 92 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Pleurodesis aims to obliterate the pleural space by producing extensive adhesion of the visceral and parietal pleura, in order to control relapse of either pleural effusions (mostly malignant) or pneumothorax. A tight and complete apposition between the two pleural layers is a necessary condition to obtain a successful pleurodesis, but--besides this mechanical aspect--there are many biological mechanisms that appear to be common to most of the sclerosing agents currently used. Following intrapleural application of the sclerosing agent, diffuse inflammation, pleural coagulation-fibrinolysis imbalance (favoring the formation of fibrin adhesions), recruitment and subsequent proliferation of fibroblasts, and collagen production are findings in the pleural space. The pleural mesothelial lining is the primary target for the sclerosant and plays a pivotal role in the whole pleurodesis process, including the release of several mediators like interleukin-8, transforming growth factor-β and basic fibroblast growth factor. When the tumor burden is high, normal mesothelial cells are scarce, and consequently the response to the sclerosing agent is decreased, leading to failure of pleurodesis. Also, the type of tumor in the pleural cavity may also affect the outcome of pleurodesis (diffuse malignant mesothelioma and metastatic lung carcinomas have a poorer response). There is general agreement that talc obtains the best results, and there are also preliminary experimental studies suggesting that it can induce apoptosis in tumor cells and inhibit angiogenesis, thus contributing to a better control of the malignant pleural effusion. There is concern about complications (possibly associated with talc but other agents as well) related to systemic inflammation and possible activation of the coagulation cascade. In order to prevent extrapleural talc dissemination, large-particle talc is recommended. Although it could--to some degree--interfere with the mechanisms leading to pleurodesis and a carefully balanced clinical decision has therefore to be made, prophylactic treatment with subcutaneous heparin is recommended during hospitalization (immediately before and after the pleurodesis procedure).

Copyright © 2012 S. Karger AG, Basel.

In plain English

This article was a narrative review, in a thematic review series, of how pleurodesis works. Pleurodesis is a treatment that makes the two layers of the pleura (the lining around the lungs) stick together so that fluid or air cannot build up again. The authors reviewed published work, including their own group's, on the mechanisms involved and on the agents used, mainly talc. In their personal series of 460 patients with tumors in the pleura treated with talc, pleurodesis was completely successful in 326 (70.9%) and failed in 58 (12.6%). Among the 69 patients with mesothelioma, it was completely successful in 41 (59%) and failed in 17 (25%). In a two-center study by their group, fluid caused by mesothelioma and lung cancer was particularly prone to pleurodesis failure. The authors concluded that complications might be reduced with large-particle talc and preventive heparin during the hospital stay, though heparin could to some degree interfere with pleurodesis. The article did not discuss asbestos.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Narrative review (part of a thematic review series), which also presents a table from the authors' personal series of talc pleurodesis patients
• Who was studied: Published studies on pleurodesis, plus the authors' personal series of 460 patients with tumors in the pleura of different origins (including 69 with mesothelioma) treated with talc pleurodesis. The article does not give the dates or place of the series.
• Exposure: Sclerosing agents placed into the pleural space to cause pleurodesis, mainly talc (as poudrage or slurry), with others discussed (doxycycline, tetracycline, iodopovidone, silver nitrate, and TGF-beta-2 in rabbits). Asbestos exposure was not studied.
• Main results:
  • In the authors' personal series of 460 patients with tumors in the pleura treated with talc, pleurodesis was a complete success in 326 (70.9%), a partial success in 76 (16.5%) and a failure in 58 (12.6%).
  • Among the 69 patients with mesothelioma in that series, pleurodesis was a complete success in 41 (59%), a partial success in 11 (16%) and a failure in 17 (25%). Median survival after pleurodesis was 9.6 months (0.5–58).
  • In the same series, pleurodesis was a complete success in 72 of 109 patients (66%) with lung tumors and in 74 of 95 patients (78%) with breast tumors.
  • In a two-center study by the authors' group, the type of tumor significantly affected pleurodesis success regardless of the agent used. Fluid caused by mesothelioma and lung cancer was particularly prone to failure, and outcomes seemed better with breast or ovarian cancer.
  • In the authors' thoracoscopy series, talc pleurodesis was completely successful in 79% of patients with a pleural fluid pH of about 7.30 or higher (the comparison sign is garbled in the text). It succeeded in only 40% of those with pH below 7.20, and in none of those with pH below 7.15.
  • The authors' group found that activation of the body's clotting system was frequently seen after talc poudrage, and reported that this could be partially controlled with preventive heparin.
• The authors' conclusion: The authors concluded that complications of pleurodesis might be reduced by using large-particle talc and preventive heparin injections under the skin during the hospital stay. They added that heparin could to some degree interfere with successful pleurodesis, so the pros and cons have to be weighed.
• Limitations the authors state:
  • The authors stated that the cellular mechanisms of pleurodesis are not yet fully understood.
  • The authors stated that the possible anti-tumor effect of talc still needs to be confirmed in larger series.
  • The authors stated that the clinical relevance of their finding that IL-8 activates clotting and correlates with survival after talc pleurodesis is still unclear.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Talc and vermiculite.

Medical terms in this study, explained in our Lexicon: Pleurodesis, Parietal Pleura, Pleural Effusion, Pneumothorax, Inflammation, Fibroblast, Collagen, Tumor Burden.

Related studies

• Tumor type influences the effectiveness of pleurodesis in malignant effusions — S. Bielsa, P. Hernández, et al. (2011)
• CT appearances of talc pleurodesis — S. Narayanaswamy, S. Kamath, et al. (2007)
• Survival in patients with malignant pleural effusion undergoing talc pleurodesis — M. Hassan, R.M. Mercer, et al. (2019)
• Success rate of medical thoracoscopy and talc pleurodesis in malignant pleurisy: A single-centre experience — J. Leemans, C. Dooms, et al. (2018)
• Indwelling pleural catheter versus talc pleurodesis for malignant pleural effusion: a meta-analysis — M. Yeung, E.W. Loh, et al. (2020)
• Comparison of the effectiveness of some pleural sclerosing agents used for control of effusions in malignant pleural mesothelioma: a review of 117 cases — A. Senyiğit, H. Bayram, et al. (2000)

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