Pleurodesis is a medical procedure in which the pleural space is artificially obliterated by creating adhesion of the two pleurae. This prevents the accumulation of either air or liquid in the pleural space.
It is mostly done for malignant pleural effusions. It can also be required in some benign effusions.
Pleurodesis is just a local therapy for control of symptoms and does not treat the disease.
Indications for Pleurodesis
Most of the patients undergoing a pleurodesis procedure have symptomatic malignant pleural effusion.
The main indication for treatment in such cases is to alleviate dyspnea. This depends on both the volume of the effusion and the underlying condition of the lungs and pleura.
Not all the patients with malignant pleural effusion benefit from the procedure. Following patients are candidates for pleurodesis
- Failure of oncological treatment to control pleural effusion
- Relief of dyspnea after drainage of the pleural cavity
- Full pulmonary expansion on chest x-ray
- Karnofsky performance status index > 70
- Absence of lymphagitis
Pleurodesis in recurrent benign pleural effusion is rarely done.
- Factors associated with worst prognosis of pleurodesis
- Acidic pH of the fluid [<7.3]
- Low glucose levels in fluid [<60 mg/dl]
- Presence of chylothorax
- Lung entrapment
It is generally avoided in patients with cystic fibrosis, if possible, because lung transplantation becomes more difficult following this procedure.
Mechanisms Involved in Pleurodesis
A tight and complete apposition between the visceral and parietal pleura is required to accomplish a successful pleurodesis.
After drainage of the pleural cavity, the two pleural layers are in contact . A strong irritation of the pleural surface is triggered following instillation of a chemical agent into the pleural space..
A second critical response to a sclerosing agent is the initiation of the coagulation cascade and the decrease in the pleural fibrinolytic activity.
The formation of a fine latticework of fibrin between the visceral and parietal pleura initiates the third step of the inflammatory cascade
The cellular mechanisms involved in pleurodesis are not yet fully understood, but it seems that – besides mesothelial cells and inflammatory cells recruited from the play an essential role.
Types of Pleurodesis
Depending upon the method used to achieve the pleurodesis, the pleurodeis could be
Mechanical – Abrasion of pleurae is carried out surgically
Chemical – Instillation of irritating chemical substances (talc, doxycycline, silver nitrate or bleomycin) into the pleural space
Immunological- – Induction with Corynebacterium parvum, transforming growth factor-beta (TGF-ß) or interferon-alpha 2 (IFN-a 2).
Among the mechanical stimuli, abrasion is the principal method. Abrasion is carried out during conventional or video-assisted thoracic surgery.
The surgeon exfoliates the pleural mesothelium, creating friction with a rough-surfaced material like gauze. This irritation results in the desquamation of the mesothelium and activation of the inflammation and coagulation pathways.
Pleural abrasion is currently used rarely.
This involves instillation of a sclerosing agent which would cause inflammation and adhesion of the two layer of pleurae.
Talc is classically considered the most efficacious sclerosant and currently most popular option.
It’s also the least expensive to administer.
Despite its low rate of complications, its use has been associated with acute respiratory distress.
Povidone-iodine and doxycycline are other seclerosing agents used.
Chief among the immunostimulants is C. parvum. Its principal advantage is that it does not require surgical intervention or pleural drainage and can be introduced into the pleural space through a simple puncture. But evidence for efficacy is still lacking.
Other immunostimulant agents include staphylococcal superantigen and TGF-beta.
Procedure of Pleurodesis
Route of access is defined as the method by which the sclerosing agent is given access to the pleural space, either through
- Classical thoracotomy
- Video-assisted surgery
- Thoracic drainage [thoracotomy tube] with local anesthesia
- thoracic drainage with thoracic puncture and a small-caliber catheter.
The current evidence suggests there is no difference between the use of large-caliber thoracic drains and small-caliber thoracic drains (catheters).
Once all the fluid has been removed, asbestos-free talc will be inserted into the pleural space, mostly through a chest tube to cause inflammation in the pleural cavity. After the talc has been administered, patients will be asked to lie down for a few hours and periodically change positions so that the talc is evenly distributed throughout the pleural space. Once sufficiently distributed, the talc will be removed via the same chest tube.
As the talc is suctioned from the pleural cavity, the pleural space will become sealed with scar tissue. Substances like bleomycin, tetracycline, silver nitrate, nitrogen mustard and povidone iodine can also be used in substitute of talc.
Successful pleurodesis is considered as long-term relief of symptoms related to the effusion, with absence of fluid reaccumulation on chest radiographs until death.
The following side effects and complications have been reported with a pleurodesis
- Chest pain
- Cardiovascular complications (rare)
- Adult Respiratory Distress Syndrome (rare)
- Possible activation of systemic coagulation after pleurodesis
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