| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Guest Access | Sign In via User Name/Password
|
|
|
|||||||
Guest Access | Sign In via User Name/Password |
|||||||||
Dr. Bouros is Associate Professor of Pneumonology, Dr. Froudarakis is Lecturer of Pneumonology, and Dr. Siafakas is Professor of Pneumonology, Department of Pneumonology, Medical School, University of Crete, and University Hospital, Heraklion, Greece.
Correspondence to: Demosthenes Bouros MD, FCCP, Department of Pneumonology, Medical School, University of Crete, Heraklion, Greece 71110; e-mail: bouros{at}med.uoc.gr
"It’s often better to be in chains than to be free."
The Trial (1925), Franz Kafka
Pleurodesis, from the Greek pleura and desis (binding together), is intended to achieve a symphysis between parietal and visceral pleura, in order to prevent accumulation of either air (pneumothorax) or fluid (pleural effusion) in the pleural space.
The most common indication for this procedure is malignant effusions; less common are pneumothorax and recurrent, benign pleural effusions.1 2 Approximately, 50% of pleural effusions are malignant, while carcinoma of the lung, metastatic breast carcinoma, and lymphoma are responsible for approximately 75% of all malignant pleural effusions.1 2 3
The methods of pleurodesis include intrapleural instillation of a sclerosant agent, surgical abrasion with a dry gauze sponge, and videothoracoscopy. The instillation of sclerosant agent is performed through a conventional large-bore or a more comfortable small-bore chest tube,1 2 3 4 and recently through videothoracoscopy.4 Preliminary data on ambulatory sclerotherapy are encouraging.5
Criteria for a successful pleurodesis attempted in a patient with
malignant pleural effusion include reexpandable lung, complete removal
of the fluid (< 100 mL drainage in 24 h), and reasonably long
expected survival. A low pleural fluid pH (< 7.20) is a good
predictor for the presence of a trapped lung, low pleurodesis rate, and
short expected survival.6
7
However, Aelony et
al8
reported that thoracoscopic talc poudrage in malignant
pleural effusions was successful in 22 of 25 patients (88%) despite
low pleural pH (
7.3).
The mechanism of pleurodesis is based on pleural irritation in order to create an inflammatory reaction leading to fibrogenesis.9 The cellular and molecular mechanisms involved in pleurodesis include the activation of the coagulation cascade of the pleura; fibrin deposition; fibroblast recruitment, activation, and proliferation; and collagen deposition.10 Furthermore, research suggests that systemic activation of coagulation takes place during pleurodesis.3 Thus, prevention of systemic activation of coagulation with prophylactic heparin should be taken into account in patients who are undergoing pleurodesis for palliative treatment of malignant effusion.3 However, the exact pathogenetic mechanism and factors that influence the outcome of pleurodesis are not well known and warrant further investigation.
The ideal pleural sclerosing agent should be easily administered, safe,
inexpensive, and widely available. None of the agents presently used
meet all of these criteria, and the search is still on. During the past
years, a huge variety of sclerotic agents have been tested, with
various success rates and drawbacks. They include talc, antibiotics
(tetracyclines, minocycline, doxycycline), antimalarials (quinacrine,
mepacrine), antineoplastic drugs (bleomycin, mitomicin, thiotepa,
nitrogen mustard), 50% glucose and water, immunomodulating agents
(interferon [IFN]-
, IFN-
), iodopovidone, radioactive colloidal
gold, autologous blood, fibrin glue, biological agents (suspension of
killed Corynebacterium parvum, or bacille
Calmette-Guérin), and finally
nitrates.1
2
3
4
11
12
13
14
15
16
17
There is still controversy and ongoing investigation as to which drug produces the best results. The existing data are inconclusive, primarily due to variability in the design and interpretation of the studies. Among them talc, either aerosolized or in a slurry (talc powder diluted in saline solution), is the agent used most commonly at the present time, and it has achieved the best results, with an average success rate near 90%.3 12 18 However, respiratory complications or even deaths have been reported,19 although these complications can be avoided by choosing the right powder in the right dose.
Tetracycline, the drug used most commonly in the 1980s, is no longer available, but minocycline and doxycycline are good alternatives. Silver nitrate was widely used in the past, but abandoned on account of side effects. In the 1980s, Wied et al16 compared silver nitrate pleurodesis with tetracycline, and they observed no differences in recurrence frequency, but the time of hospitalization was significantly longer in the silver nitrate group. Furthermore, they found a decrease of exudation and a decreased use of analgesics in the tetracycline group. As a consequence, the silver nitrate method was abandoned and tetracycline was recommended as the treatment of choice for pleurodesis in primary spontaneous pneumothorax. In a previous study, Vargas et al17 have demonstrated that a small concentration (0.5%) of silver nitrate instilled into the pleural space was effective for producing pleurodesis in the rabbit and was comparable to tetracycline, 35 mg/kg.
Lately, thoracoscopy (medical and surgical) is increasingly applied and is preferable for the treatment of pneumothorax, especially in young patients.5 20 Jerram et al21 studied the efficacy of thoracotomy with mechanical abrasion and talc slurry through videothoracoscopy as methods of pleurodesis in normal dogs. They found that obliteration grade and costal pleural fibrosis score were significantly higher for the treated sides in the mechanical abrasion dogs, compared with the talc slurry-treated dogs. Neither method of pleurodesis produced sufficient pleural adhesions to obliterate the pleural space.
In this issue of CHEST (see page 808), Vargas et al compared the efficacy of silver nitrate and talc slurry in producing pleurodesis in a rabbit model. They found that the macroscopic and microscopic score of pleurodesis was significantly greater in the rabbits that received silver nitrate, but the distribution of thick and thin collagen fibers did not differ between the two groups.
However, some caveats are important: (1) The level of inflammation was assessed only after 28 days from the sclerosant injection. It is reasonable to expect a change in the ratio of immature to mature collagen fibers at a later time. (2) The type of collagen fibers deposited in the pleura is not known; therefore, it could be different between the various sclerosants. (3) It is somewhat worrisome that 2 of the 10 rabbits that received silver nitrate developed hemothorax, while 6 developed atelectasis. Furthermore, alveolar inflammation and mediastinal shift were significantly greater in the silver nitrate group. In this concept, dose-defining studies are still lacking. (4) Since this is an experimental study, it is not known whether there are differences in the hospitalization time between the two agents. Earlier studies have shown greater hospitalization time in silver nitrate in comparison to tetracycline.16 (5) It is not known if the involving cytokines and the fibrogenic process are different between the two agents.
Finally, if the results of Vargas et al are confirmed in properly designed, controlled, double-blind studies in humans, silver nitrate could become the sclerosant of choice, given its wide availability and inexpensiveness.
References
in the control of malignant pleural effusions (preliminary results) [abstract]. Am J Respir Crit Care Med 151,A850
This article has been cited by other articles:
|
|
 |
|
  N. A. Avila, A. J. Dwyer, A. Rabel, R. M. DeCastro, and J. Moss CT of Pleural Abnormalities in Lymphangioleiomyomatosis and Comparison of Pleural Findings After Different Types of Pleurodesis. Am. J. Roentgenol., April 1, 2006; 186(4): 1007 - 1012. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. E. Froudarakis, M. Klimathianaki, and M. Pougounias Systemic inflammatory reaction after thoracoscopic talc poudrage. Chest, February 1, 2006; 129(2): 356 - 361. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. J. Gallivan Pleurodesis and Silver Nitrate Chest, May 1, 2001; 119(5): 1624 - 1624. [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
