El marco analítico de los estudios sobre escuelas eficaces

The pleural space is 10 to 20 µm in width and normally contains about 0.1 mL/kg of fluid.

A volume greater than 7 to 14 mL is abnormal. Many mechanisms can result in abnormal amounts of pleural fluid, including:

 Increased hydrostatic pressures in the microvascular circulation.

 Decreased oncotic pressures in the microvascular circulation.

 Decreased pleural space pressure (resulting from lung collapse).

 Increased permeability of the microvascular circulation.

 Obstruction of lymphatic drainage

Generally, transudative effusions are formed in response to increased hydrostatic pressure, while exudative effusions form when pleural inflammation or disrupted lymphatic drainage results in increased protein leak or decreased protein removal from the pleural space. In CHF, pleural effusions are secondary to pulmonary venous hypertension.

Neoplasms can cause pleural effusions by direct involvement of the pleura, by lymphatic obstruction, or in association with a post-obstructive pneumonia. Pleural effusions associated with pulmonary embolism are secondary to increased capillary permeability, pleuropulmonary hemorrhage, and increased hydrostatic pressure.

34 Many different things can cause pleural effusion. Heart failure or other heart and lung problems may cause pleural effusion. Infections (in-FECK-shuns) such as pneumonia (noo-MOH-nyah) or tuberculosis (TB) may cause pleural effusion. Inflammation of the pleura, called pleurisy (PLOOR-i-see), may cause pleural effusion. Other causes may include cancer, injury, or problems with other organs in your chest or abdomen (belly).

Pleural effusion is a secondary disease being related to tuberculosis or other lung disease such as TB, pneumonia etc. because there is irritation on the lining of pleural cavity, thus altering the permeability of the membrane and decreasing the oncotic pressure needed to drain the excess fluid in the pleural space. normally there is a small amount of pleural fluid in the pleural space that lubricates the parietal and visceral pleura during expiring and inspiring.

Primary pulmonary tuberculosis is often asymptomatic, so that the results of diagnostic tests are the only evidence of the disease. Although primary disease essentially exists subclinically, some self-limiting findings might be noticed in an assessment. Associated paratracheal lymphadenopathy may occur because the bacilli spread from the lungs through the lymphatic system. If the primary lesion enlarges, pleural effusion is a distinguishing finding. This effusion develops because the bacilli infiltrate the pleural space from an adjacent area. The effusion may remain small and resolve spontaneously, or it may become large enough to induce symptoms such as fever, pleuritic chest pain, and dyspnea. Dyspnea is due to poor gas exchange in the areas of affected lung tissue.

Dullness to percussion and a lack of breath sounds are physical findings indicative of a pleural effusion because excess fluid has entered the pleural space.

COMPLICATION

Complications of pleural effusions include collapse of the lung; pneumothorax, or air in the chest cavity, which is a common side effect of the thoracentesis procedure; and empyemas (abscesses) caused by infection of the pleural fluid, which require drainage of the fluid.

Pleural effusion can place patients with asbestosis or mesothelioma at even more risk than other patients — if it leads to difficulty breathing. This is because patients with these conditions so often suffer from pleural scarring, which itself makes it extremely difficult to breathe. Pleural effusion can exacerbate this problem, and ultimately the inability to breathe properly can contribute significantly to the patient's downward spiral.

35 Risks:

A pleural effusion may cause or worsen a lung infection, such as pneumonia. The extra fluid may get infected and form a pocket of pus, which is called empyema (em-peye-EE-ma). You may have other problems, such as a collapsed lung. The problems you may have depend on what is causing your pleural effusion. Talk to your caregiver about any concerns you may have about your illness or treatment.

TREATMENT

In some cases, no treatment is required for pleural effusions. However, when doctors link the fluid build-up to a patient's discomfort or pain — or to other, more serious side effects

— they often take measures to address the cause and/or effects of the effusion. As previously mentioned, a patient suffering from asbestosis or mesothelioma may experience more than one condition that makes it difficult to breathe. To address this, doctors do whatever they can to treat the root causes.

For patients with pleural-effusion-related breathing problems, this may include the following:

Thoracentesis. Further extraction of pleural fluid can alleviate pressure in the chest, making it easier to breathe.

Once a pleural effusion is diagnosed, the cause must be determined. Pleural fluid is drawn out of the pleural space in a process called thoracentesis. A needle is inserted through the back of the chest wall in the sixth, seventh, or eighth intercostal space on the midaxillary line, into the pleural space. The fluid may then be evaluated for the following:

1. Chemical composition including protein, lactate

dehydrogenase (LDH), albumin, amylase, pH, and glucose 2. Gram stain and culture to identify possible bacterial infections 3. Cell count and differential

4. Cytopathology to identify cancer cells, but may also identify some infective organisms

5. Other tests as suggested by the clinical situation – lipids, fungal culture, viral culture, specific immunoglobulins

Chemical pleurodesis. This procedure involves the insertion of agents such as talc or bleomycin to eliminate the pleural space altogether, so that fluid can no longer build up.

36 Therapeutic aspiration may be sufficient; larger effusions may require insertion of an intercostal drain (either pigtail or surgical). When managing these chest tubes, it is important to make sure the chest tubes do not become occluded or clogged. A clogged chest tube in the setting of continued production of fluid will result in residual fluid left behind when the chest tube is removed. This fluid can lead to complications such as hypoxia due to lung collapse from the fluid, or fibrothorax, later, when the space scars

down. Repeated effusions may require chemical

(talc, bleomycin, tetracycline/doxycycline), or surgical pleurodesis, in which the two pleural surfaces are scarred to each other so that no fluid can accumulate between them.

This is a surgical procedure that involves inserting a chest tube, then either mechanically abrading the pleura or inserting the chemicals to induce a scar. This requires the chest tube to stay in until the fluid drainage stops. This can take days to weeks and can require prolonged hospitalizations. If the chest tube becomes clogged, fluid will be left behind and the pleurodesis will fail.

Pleurodesis fails in as many as 30% of cases. An alternative is to place a PleurX Pleural Catheter or Aspira Drainage Catheter. This is a 15Fr chest tube with a one-way valve.

Each day the patient or care givers connect it to a simple vacuum tube and remove from 600 cc to 1000 cc of fluid. This can be repeated daily. When not in use, the tube is capped.

This allows patients to be outside the hospital. For patients with malignant pleural effusions, it allows them to continue chemotherapy, if indicated. Generally the tube is in for about 30 days and then it is removed when the space undergoes a spontaneous pleurodesis.

Pleural decortication. Also called pleurectomy, this surgery removes the pleura; like chemical pleurodesis, pleural decortication eliminates the pleural space, thereby preventing pleural fluid from building up.

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The treatment you receive may depend on what is causing your pleural effusion and how bad your symptoms are. You may need medicines such as antibiotics (an-ti-bi-AH-tiks) to

37 prevent or treat a bacterial (bak-TEE-ree-al) infection. Steroids and other kinds of medicines may be given to decrease inflammation. You may need medicines for pain.

Diuretic (deye-yoo-RET-ik) medicine may help you lose extra fluid caused by heart failure or other problems. You may need to have the extra pleural fluid removed by having a thoracentesis (thohr-ah-sen-TEE-sis) or a chest tube. During a thoracentesis, a needle is used to remove the extra pleural fluid from around a lung. This fluid may be sent to the lab for tests. A thoracentesis may help you breathe easier, and help your caregiver find the best way to treat you. A chest tube is a tube that stays in your chest for days or weeks.

This lets the extra fluid around your lung drain out over time. You may need medicines put directly into your chest if the fluid does not drain out easily.

Some people have pleural effusions that come back over and over. For example, a tumor (growth) may cause extra fluid to keep collecting around a lung. If your pleural effusion keeps coming back or if it increases your risk for other problems, you may need surgery or other treatments. Ask your caregiver for more information about other treatments that you may need.

38 BIBLIOGRAPHY

Arun Gopi, Sethu M. Madhavan, Surendra K. Sharma and Steven A.Sahn. 2007.

Diagnosis and Treatment of Tuberculous Pleural Effusion in 2006. American College of Chest Physicians.

http://ccn.aacnjournals.org/content/29/2/34.full

http://www.allaboutmalignantmesothelioma.com/pleural-effusion.htm

http://www.consultantlive.com/display/article/10162/36884

http://www.medicinenet.com/pleural_effusion/page2.htm#risk

W, Aru. Sudoyo, et all. 2006. Ilmu Peyakit Dalam Ed IV Jilid I. Departemen Ilmu Penyakit Dalam FKUI, Jakarta.

Yoga, Tjandra Aditama. 2006. TUBERKULOSIS PEDOMAN DAN PENATALAKSANAAN DI INDONESIA. Perhimpunan Dokter Paru Indonesia, Jakarta.