Pleural Effusion Notes PDF

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Notes contain: definition, pathophysiology, clinical presentation, investigations and Dx, MGMT...

Description

Pleural Effusion Definition: A pleural effusion is a collection of fluid in the pleural space. Effusions can have multiple causes, which can be pulmonary, pleural or extrapulmonary. Effusions are usually classified as transudates or exudates, however, blood (haemothorax, HTX), pus (empyema) or chyle (chylothorax, CTX) can also accumulate in the pleural space.

Pathophysiology: The parietal and visceral pleural surfaces are normally in close contact and the potential space between them, the pleural space, contains only a very small amount of pleural fluid. This fluid lubricates the movement between the pleura. Pleural fluid enters the pleural space from systemic capillaries in the parietal pleurae and exits via parietal pleural stomas and lymphatics. The fluid eventually drains in to the R atrium (clearance is partly dependent on Rsided pressures). A pleural effusion occurs when the volume of pleural fluid is greater than normal, either due to excess fluid entering or little exiting the pleural space.

Schematic of the pleural space in pleural effusion (a) and the physiology of fluid balance (b). (a) The lungs, the parietal and visceral pleura, which surround them and the pleural space with accumulated pleural effusion (b) Visceral space, the pleural space and the parietal space. The balance of forces depends on the oncotic and hydrostatic pressures. The pleural space has a slightly negative pressure (~ −5mmHg), due to the surface tension of the alveolar fluid, as well as the elasticity of the lungs and thoracic wall; this enables the lungs to remain inflated. Due to higher hydrostatic pressures on the parietal pleura (30mmHg) than the visceral pleura (24mmHg), there is fluid production from the parietal pleura, leading to oncotic pressure being at equilibrium (29mmHg in both). The lymphatic vessels on the parietal pleura are responsible for most of the resorption.

Category of Effusion

Cause

Transudative

a combination of  hydrostatic pressure and  plasma oncotic pressure across the pleural membranes

Exudative

usually as a result of inflammation   permeability of the pleural surface and/or capillaries,  exudation of fluid, protein, cells, and other serum constituents

Chylous

disruption of thoracic duct  presence of chyle in pleural space

Haemothorax

trauma (commonly) or rupture of a major blood vessel (less common), e.g. aorta or pulmonary a.  bloody fluid in pleural space

Empyema

• uncomplicated para-pneumonic effusion  exudative fluid in the pleural space (without direct bacterial invasion) • complicated para-pneumonic effusion  bacterial invasion of the pleural space • pleural empyema  accumulation of pus in the pleural cavity

Common Associated Condition(s) • heart failure (HF) • cirrhosis ± ascites • hypoalbuminaemia (usually due to nephrotic syndrome) • peritoneal dialysis • pneumonia • malignancy − ♀ breast cancer − ♂ lung cancer − large unilateral (U/L) pleural effusions are more commonly due to malignancy • neoplasms − lymphoma − metastatic carcinoma • trauma • tuberculosis (TB) • cirrhosis • amyloidosis • sarcoidosis • most commonly due to penetrating or blunt trauma • iatrogenic trauma • other causes: − malignancy − coagulation disorders • most common cause: pneumonia  extension of bacterial infection to the pleural space • less common − infected haemothorax − ruptured lung abscess − oesophageal tear − thoracic trauma

Transudative vs. Exudative pleural fluid. The accumulated pleural fluid, as seen in pulmonary effusion, can be described as either transudate or exudate depending on the movement of the fluid as well as the underlying pathological mechanisms.

Clinical Presentation: Some pleural effusions are asymptomatic and are discovered incidentally, though in the majority of patient physical examination reveals absent tactile fremitus, dullness to percussion, and decreased breath sounds on the same side of the effusion. However, as these findings can also be caused by pleural thickening, a physical examination alone has low sensitivity and specificity for detecting pleural effusion. Therefore, other investigations, primarily a chest X-ray (CXR), should also be carried out.

Inspection

• dyspnoea − with large-volume effusion   RR and shallow • (mild) non-productive cough • chest pain − usually felt over the inflamed site − ± sharp pain worse during inspiration  indicates inflammation of parietal pleura Also inspect for: • any evidence of weight loss and/or underlying malignancy • nicotine staining on finger • finger clubbing • rheumatoid changes in hands • use of accessory muscles of respiration • reduced chest movement and/or unequal chest expansion

Palpation

Percussion Auscultation

•  tactile vocal fremitus  due to fluid in pleural space •  chest expansion on affected side • deviated trachea − large U/L effusion  away from affected side − + associated collapse  towards affected side • stony dullness on percussion − LAT, it may rise up towards the axilla • crackles at the upper edge of effusion • pleural fiction rub − may be heard during inspiration and expiration •  /absent breath sounds over the effusion − absent vocal resonance over the effusion, except at its upper surface (= ‘aegophony’ - sounds like a goat bleating)

Investigations & Dx: Pleural effusion is suspected in patients with pleuritic pain, unexplained dyspnea, or suggestive signs. Diagnostic tests are indicated to demonstrate the presence of pleural fluid and to determine its cause. Detection and diagnosis of a pulmonary effusion is by physical examination and CXR, though pleural fluid analysis (following a thoracocentesis) may also be required in some pts. Imaging A CXR is the first investigation if a pleural effusion is suspected clinically. Further initial investigations include USS, CT and MRI.

Imaging Technique

CXR

USS

CT

Comment

Findings

• the first investigation carried out if suspecting pleural effusion • PA film will be sufficient  LAT views are rarely needed − ~200mL of fluid is required to be visible on PA view − 50mL  costophrenic blunting visible on LAT view •  sensitive than CXR for detecting pleural effusions • can detect very small effusions (35mL) • can be used to plan thoracocentesis

• typically unilateral (U/L) − transudative U/L effusions are  common than B/L exudative effusions • blunting of costophrenic and cardiophrenic angles • homogenous density • meniscus-shaped margin • hypo/anechoic structures in the costodiaphragmatic recess • the defining USS features of effusion are the quad sign and sinusoid sign − quad sign: the usual boundaries defining a pleural effusion − sinusoid sign: underlying lung is submerged in a pleural effusion  inspiratory decrease in the depth of the effusion

• not routinely indicated • cannot distinguish between transudative and exudative pleural effusions • can differentiate between pleural effusion and pleural empyema • valuable for evaluating: − underlying lung parenchyma for infiltrates or masses − insufficient detail from the CXR for distinguishing loculated fluid from a solid mass

Frontal CXR of a pleural effusion. CXR shows blunting of the right costophrenic recess, suggestive of a right-sided pleural effusion. Normal left costophrenic recess.

CXR of a massive pleural effusion. CXR of a 65-year-old male, presenting with severe shortness of breath and recent weight loss. This ‘white out’ is the result of a massive left sided pleural effusion with marked mediastinal shift. The heart and trachea as severely displaced to the right. Right lung clear.

D F L

Chest CT with contrast (axial view, ~T5) of a bilateral pleural effusion. CT shows bilateral crescent-shaped attenuated areas (green colour).

AA = ascending aorta, DA = descending aorta, PT = pulmonary trunk, VC = superior vena cava, PA = right pulmonary artery, V = vertebra.

USS of a pleural effusion. USS of the right infrascapular region. Fluid (F) is visible in the right costodiaphragmatic recess as an anechoic region between the pulmonary parenchyma above and the hyperechoic diaphragm (D) overlying the liver (L).

Thoracentesis & Pleural Fluid Analysis Thoracentesis and subsequent pleural fluid analysis are done to diagnose the cause of pleural effusion. Category of Effusion Transudative Exudative

Chylous

Haemothorax

Empyema

• • • • • • • •

• • • • • •

Fluid Content & Appearance protein level of 30g/L froths when shaken clots when left standing exudative effusion cloudy, milky-white fluid  concentrations of lipids (triglyceride >1.24mM/L, cholesterol 0.6

pleural fluid LDH pleural fluid LDH 2/3rd upper limit of normal serum LDH

Management: Management should be aimed at the underlying disease. Transudative Effusion • if a transudate is confirmed  aspiration should be avoided • if pt is well  diuresis can be initiated • if pt is symptomatic  therapeutic thoracocentesis Exudative Effusion • if an infective cause  prescribe ABx • thoracocentesis may be an option, though if there is a risk for the effusions reaccumulating, despite repeated aspirations and systemic therapy  semipermanent pleural drain or video-assisted thoracoscopic surgery (VATS) pleurodesis can be considered

Pleurodesis: • = obliteration of pleural space • causes adhesion of the visceral and parietal pleural  prevents reaccumulation of effusion • common agents used include tetracycline, talc poudrage (sterile talc) and bleomycin • most often used in the management of recurrent malignant effusions

Complications: • •

depends on the cause of pleural effusion presence of a malignant pleural effusion  poor prognosis  median survival following Dx 3-12mo, depending on cell type

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