Pleural Effusions

Can-mao XieDept. of Pulmonary & Critical Care Medicine

1st Affiliated Hospital of Sun-Yat Sen University

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Contents Anatomy and Mechanism of pleural fluids

turnover Etiology and pathogenesis of pleural

effusions Clinical manifestations Radiographic Examination Approach to the patient with pleural effusions Management of patient with pleural effusions

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The pleural space is not really a space but rather a potential space between the lung and chest wall.

It is a crucial feature of

the breathing apparatus

since pleurae serves as

a coupling system between

the lung and chest wall.

Introduction

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Introduction

There is normally a very thin layer of fluid (from 2 to 10 m thick) between the two pleural surfaces, the parietal pleura and visceral pleura. The pleural space and the fluid within it are not under static conditions. During each respiratory cycle the pleural pressures and the geometry of the pleural space fluctuate widely. Fluid enters and leaves the pleural space constantly .

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Anatomy of the Pleural Space

The serous membrane covering the lung parenchyma is called the visceral pleura. The remainder of the lining of the pleural cavity is designated the parietal pleura. The parietal pleura receives its blood supply from the systemic capillaries.

The visceral pleura is supplied predominantly by branches of the bronchial artery in humans.

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SC: Systemic capillaries PC: Pulmonary capillaries

The lymphatic vessels in the parietal pleura are in direct communication with the pleural space by means of stomas. These stomas are the only route through which cells and large particles can leave the pleural space.Although there are abundant lymphatics in the visceral pleura, these lymphatics do not appear to participate in the removal of particulate matter from the pleural space.

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SC: Systemic capillaries PC: Pulmonary capillaries

Anatomy of the Pleural Space

Figure 1. Anatomy of the pleural spaceSC: Systemic capillaries PC: Pulmonary capillaries

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stomas

stomas

electronic microscopy

Figure 2. pleural fluids turnoverPF enter the pleural space through parietal & visceral pleurae,And leave pleural space through lymphatics in parietal pleura

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Pathophysiology Pleural fluid will accumulate when the rate

of pleural fluid formation is greater than the rate of pleural fluid removal by the lymphatics.

Pleural effusions have classically been divided into

Transudative exudative

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A transudative pleural effusion occurs when alterations in the systemic factors that influence pleural fluid movement result in a pleural effusion. Examples are elevated visceral pleural capillary pressure with left heart failure, elevated parietal pleural capillary pressure with right heart failure, and decreased serum oncotic pressure with the nephrotic syndrome, hepatic cirrhosis.In contrast, exudative pleural effusions occur when the pleural surfaces themselves are altered. Inflammation of the pleura, leading to increased protein in the pleural space, is the most common cause of exudative pleural effusions.

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Pathophysiology

Etiology and Pathogenesis

Many diseases can cause pleural effusionsElevated pleural capillary pressure, such as congestive heart failure, pericardial disease, increased blood volume, et alElevated pleural permeability, such as pleural inflammation, neoplastic pleural disease (metastatic disease or mesotheliomas), pulmonary emboli, systemic lupus erythematosus (SLE), et alDecreased serum oncotic pressure, such as cirrhosis, nephrotic syndrome, myxedema, et alDysfunction of parietal pleura lymphatics drainageTrauma, such as esophageal perforation, post-cardiac injury syndrome, et al

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Clinical Manifestations The symptoms of a patient with a pleural effusion are to a large extent dictated by the underlying process causing the effusion.Many patients have no symptoms referable to the effusion when effusion is small. When symptoms are related to the effusion, they arise either from inflammation of the pleura or from compromise of pulmonary mechanics.Pleuritic chest pain is the usual symptom of pleural inflammation.Irritation of the pleural surfaces may also result in a dry, nonproductive cough.With larger effusions, dyspnea results from lung compression.

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Physical Examinations

Signs are closely correlated to the volume of pleural effusions. The volume is larger, the signs is obviously. Physical examination of a patient with pleural effusion reveals :

Decreased or absent tactile fremitus, dullness to percussion

Diminished breath sounds over the site of the effusion

Bronchial breath sounds are frequently present immediately above the effusion

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Bronchial breath sounds

Diminished breath sounds

Radiographic Appearance

The first fluid accumulates in the lowest portion of the thoracic cavity, which is the posterior costophrenic angle. Therefore, the earliest radiologic sign of a pleural effusion is blunting of the posterior costophrenic angle on the lateral chest radiograph. If a posteroanterior radiograph is obtained with the patient lying on the affected side, free pleural fluid will gravitate inferiorly and a pleural fluid line will be visible.

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A posteroanterior and lateral chest radiograph of pleural effusion

blunting of the posterior costophrenic angle

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Pleural fluid is said to be loculated when it does not shift freely in the pleural space as the patient’s position is changed. Loculated pleural effusions occur when there are adhesions between the visceral and parietal pleurae. Both ultrasound and computed tomography (CT) have proved useful in making this differentiation.

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Radiographic Appearance

Approach to the Patient with Pleural Effusion

There are many different diseases that can be associated with pleural effusion.When a pleural effusion is discovered, two questions need to be answered:

a. Is the effusion a transudate (i.e., is it due to systemic factors) or is it an exudate (i.e., is it due to disease of the pleura itself)?

b. If the effusion is an exudate, what is the disease responsible for its production? Answers to these two questions can only be obtained by examining the pleural fluid. Nearly every patient with a pleural effusion should have a diagnostic thoracentesis.

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Light RW. Clin Chest Med, 2006,27:309-319

Etiology of pleural effusions

Appearance of the Pleural Fluid The gross appearance of the pleural fluid provides

useful information.

Odor of pleural fluidPutrid - probably anaerobic pleural infectionUrine - probable urinothorax unless patient is

uremic Bloody - obtain hematocrit (Hct),

<1% non-significant1 - 20%- malignancy, pulmonary embolus or

trauma>50% of peripheral hematocrit - hemothorax

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Cloudy or turbid - either cells and debris or high lipid levelsPost centrifugation – If supernatant turbid,

due to high lipid levelsTurbid supernatant - measure pleural fluid

triglyceride levelTriglyceride level > 110 mg/dl – chylothoraxTriglyceride level < 50 mg/dl and cholesterol >

250mg - pseudochylothorax50 mg/dl < Triglyceride level < 110 mg/dl -

obtain lipoprotein analysisPresence of chylomicrons - chylothorax

Appearance of the Pleural Fluid

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Separating exudates from transudates

Light’s criteria (to fit one or more of the following three) :

Pleural fluid protein/serum protein ratio > 0.5

Pleural fluid LDH/serum LDH > 0.6

Pleural fluid LDH > 2/3 upper normal limit for serum LDH

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Dr. Light raised the Light’s criteria when he was at age of 32

LDH=lactate dehydrogenase

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Routine tests on exudative pleural effusions

If the patient possibly has a transudative pleural effusion, it is most cost-effective to only measure the pleural fluid protein and LDH levels initially.

If the effusion is transudative, additional tests provide no additional information and sometimes produce misleading positive results.

Additional tests to consider ordering on exudative pleural fluids include smears and cultures for bacteria, cell count with differential, glucose levels, a pleural fluid markers for tuberculosis and pleural fluid cytology.

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Cell count and differential

The pleural fluid differential cell count is useful in the differential diagnosis of an exudative pleural effusion.

The presence of predominantly neutrophils (>50%) indicates that an acute process is affecting the pleura.

The presence of predominantly mononuclear cells indicates a chronic process.

The presence of predominantly small lymphocytes indicates that the patient most likely has malignancy, a pleural effusion post coronary artery bypass surgery or tuberculous pleuritis.

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Pleural fluid glucose levels

The presence of a low pleural fluid glucose concentration (<60 mg/dl or 3.3mmol/L) indicates that the patient probably has a complicated parapneumonic or a malignant effusion.

Less common causes of low glucose pleural effusions are hemothorax, tuberculosis and rheumatoid pleuritis.

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Pleural fluid LDH level

Although the pleural fluid LDH does not help differentiate various exudative pleural effusions, it is an indicator of the degree of pleural inflammation and should be measured each time pleural fluid is sampled from an undiagnosed pleural effusion.

Pleural LDH>500u/L indicates a possibility of neoplastic pleural disease or secondary pleural bacterial infection.

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Pleural fluid pH

If the patient has a parapneumonic or a malignant pleural effusion, a pleural fluid pH (using a blood gas machine) is indicated.

A pleural fluid pH below 7.20 in patient with a parapneumonic effusion is an indicator for drainage of the effusions.

A pleural fluid pH below 7.20 in a patient with a malignant pleural effusion indicates that the patient’s life expectancy is only about 30 days and that chemical pleurodesis is likely to be ineffective.

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Pleural fluid tests for malignancy Cytologic examination of the pleural fluid is a fast, efficient and

minimally invasive means by which this diagnosis can be established.

There have been many studies evaluating the utility of tumor markers such as CEA, CA 15-3, CA 19-9, and ENOLAS

If cutoff set high enough, there is no false positives, then it is very insensitive.

In order to be useful, the tumor marker must be complimentary to the pleural fluid cytology – The diagnostic GOLD standard for malignant pleural effusion.

Since a blind needle biopsy of the pleura adds little to cytology in diagnosing pleural malignancy, thoracoscopy is the procedure of choice for the patient with suspected malignancy and negative cytology. 31Dr. Canmao xie

Malignant effusions

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肺腺癌患者男性， 65 岁。因“反复胸痛 5 月，呼吸困难1 月，加重 1 周” 入院。胸水CEA 增高。

镜下见：脏、壁层胸膜间粘连带形成，壁层胸膜、膈面见弥漫性结节样新生物，部分表面覆盖白色坏死组织，右上叶后段斜裂缘见白色息肉样肿物，右下叶表面多发灰色斑状浸润。病理示腺癌。

Pleural fluid markers for tuberculosis

If tuberculous pleuritis is not treated, the effusion will resolve but pulmonary or extrapulmonary tuberculosis subsequently develops in more than 50%.

Since less than 40% of patients with tuberculous pleuritis have positive pleural fluid cultures, alternative means such as the level of adenosine deaminase (ADA), gamma interferon or polymerase chain reaction (PCR) are used to establish the diagnosis.

The pleural fluid ADA level above 45 IU/L is significant in establishing the diagnosis of tuberculous pleuritis.

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Parapneumonic Effusion

Any pleural effusion associated with bacterial pneumonia, lung abscess, or bronchiectasis is a parapneumonic effusion. A Gram-stain and bacterial culture (both aerobic and anaerobic) will identify infected pleural fluids. Effective antibiotics therapy is the key issue for controlling infection.If upon examination of the pleural fluid, any one of the following four conditions is met, chest tubes should be inserted immediately :

1. Gross pus is obtained on thoracentesis -- empyema ; 2. The Gram stain of the pleural fluid is positive for organisms; 3. The pleural fluid glucose level is less than 40 mg/100 ml; 4. The pleural fluid PH is below 7.00.

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Tuberculous Pleural Effusions

At the onset of tuberculous pleuritis, most patients also have pleuritic chest pain.Tuberculosis toxic syndrome– dry cough, low grade fever, night sweat and losing body weight. With a positive tuberculin skin test (PPD) and significantly high ADA level in pleural effusion. The fluid is invariably an exudate. Frequently the pleural fluid protein is over 50 g/L and this finding is very suggestive of tuberculous pleuritis. The differential white cell count reveals more than 80% lymphocytes.Pleural biopsy has its greatest utility in establishing the diagnosis of tuberculous pleuritis. The demonstration of granuloma in the parietal pleura is highly suggestive of tuberculous pleuritis. Caseous necrosis or acid-fast bacilli need to be demonstrated.

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Tuberculous Pleurisy

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Management of Tuberculous Pleural Effusions

Anti-tuberculosis chemotherapy: Adequate therapy for tuberculous pleuritis is a 9--month course of isoniazid and rifampin daily.

The performance of the therapeutic thoracentesis is highly recommended as soon as the diagnosis is confirmed.

The administration of corticosteroids will rapidly relieve the patient's symptoms of pleuritic chest pain, malaise, and fever and does not seem to lead to dissemination of the tuberculosis. Markedly symptomatic patients should be started on prednisone 40 mg/day and then gradually tapered over several weeks.

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Malignant Pleural Effusions Malignant disease involving the pleura is the second

leading cause of exudative pleural effusions. Frequent seen in patients with age>45 Ys,

manifestated by chest pain, hemoptysis and emaciate.

Bloody and massive pleural effusion is the typical clinical picture. Significantly high LDH and CEA level(>20ug/L) in pleural fluid.

Pleural fluid cytology, needle biopsy, thoracoscopy or open pleural biopsy has its greatest utility in establishing the diagnosis of malignant pleural effusions.

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Management of malignant pleural effusion

Treatment of the primary tumor. Therapeutic thoracentesis with or without a chest

tube. Chemical pleurodesis

Mechanisms of pleurodesis not clearly understood. In general, an inflammation producing agent is injected into the pleural space. Resulting inflammatory reaction leads to pleural fibrosis such that the visceral and parietal pleurae fuse.

Talc, Tetracycline Derivatives (Tetracycline, Doxycycline), Antineoplastic drugs (Bleomycin, Mitoxantrone, Nitrogen mustard) are the choice of pleurodesis agents.

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Diagnostic and Treatment Workup of a Pleural Effusion

Whether it is a pleural effusion or not ？

Is the effusion a transudate or an exudate?

What is the disease responsible for its production?

Treatment for etiology and relieving symptoms

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Thank you for attention!

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