22 March 2019 The pleural cavity is the space between the visceral pleura , which covers the lungs, and the parietal pleura , which lines the inside of the thoracic cavity. Under normal circumstances, this cavity contains only a small amount of liquid that prevents friction between the pleura during respiratory movements. In addition, the negative pressure in the pleural cavity during expiration prevents lung collapse . Abnormal accumulation in the pleural cavity of liquid of any kind, which is known as pleural effusion , can be caused by many things. What is thoracentesis, pleural drainage and pleural biopsy? Thoracentesis is the procedure for gaining access to the pleural cavity by puncture through the chest wall. It allows the following procedures to be carried out: Pleural drainage, the removal of abnormal accumulations of liquid present in the area; Pleural biopsies, the obtaining of tissue samples. How are thoracentesis, pleural drainage and pleural biopsy carried out? Thoracentesis is ideally carried out with the person sitting , leaning slightly forward and supported. However, if necessary, it can also be done with the person lying down. The site for performing a thoracentesis depends on the specific circumstances for which it is being carried out. To identify the presence and degree of pleural effusion and determine the site of thoracentesis, imaging tests may be necessary in addition to physical examination. Once the site of the thoracentesis has been determined, the skin on the area where the needle will be inserted between the 2 ribs is prepared and anaesthetised , then the needle is inserted into the pleural cavity. To perform the pleural drainage , a catheter is inserted through the needle, allowing the liquid to be drawn. In the case of a pleural biopsy , a special needle is used to collect tissue samples. Once the thoracentesis is complete, a dressing is placed on the site of the intervention. Some analgesic medication may be administered, but no other special care is required. The patient will be free to leave the hospital shortly after the procedure has been completed. They should be accompanied by someone who can provide assistance if necessary. When are thoracentesis, pleural drainage and pleural biopsy carried out? It is always for the doctor to decide whether there is a need for a particular test, depending on the individual characteristics of each person and their complaints or illness. As a rule, thoracentesis may be indicated after the presence of pleural effusion has been confirmed. Thoracentesis aims to: Determine the cause of the pleural effusion (diagnostic thoracentesis) by obtaining a sample of the effusion or pleural tissue for further analysis; Alleviate associated symptoms (therapeutic thoracentesis) through pleural drainage. Typically, a pleural biopsy is performed when it is not possible to diagnose the cause of the pleural effusion by analysis of the effusion and/or when it has specific characteristics. Contraindications for thoracentesis include: Skin lesions at the site of intervention; Coagulation disorders. How long does thoracentesis take? A thoracentesis procedure takes on average 30 minutes. However, it may take longer depending on the procedures to be carried out and the objectives of the test. Once completed, the patient should wait until they have fully recovered. This period should be spent at the hospital, resting in a place specifically provided for this purpose. What are the limitations of thoracentesis Diagnostic thoracentesis, and the procedures that may be associated with it, enables samples to be taken that will later be analysed in the clinical pathology and pathological anatomy laboratories. It is therefore highly effective in diagnosing the causes of pleural effusion. However, as with any other procedure, diagnosis may fail , even when it is carried out correctly. The use of other methods may be required. In therapeutic thoracentesis, pleural drainage may not achieve its objectives , for example in the following cases: Effusion that is extensive and repeated; When the effusive liquid is very thick, in which case a different type of intervention will be necessary. Are there any side effects, risks or complications associated with thoracentesis? Thoracentesis is a safe procedure. However, as with any other invasive procedure and although rare, there are risks associated with its implementation. The most common risks and complications include pneumothorax, cough and local pain. The following can also occur: Haemothorax; General discomfort; Feeling of faintness. And more rarely: Local infections; Pulmonary oedema; Lung injuries; Haemorrhage; Subcutaneous emphysema. This article was written with the support of physicians and other clinical professionals from the Hospital da Luz network. The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
