Case Presentation

Dr. Mahesh Chaudhary MD Radiology & Imaging, BSMMUPhase-A Resident (March 2014 session)

PLEURAL EFFUSIONS

DEFINITION- A COLLECTION OF FLUID BETWEEN THE

PARIETAL PLEURA AND VISCERAL PLEURA.

The Right Lung-Three lobes-the superior, middle and inferior, which are separated by the horizontal fissure and the oblique fissure.-10 bronchopulmonary segments

The Left Lung-Two lobes which are separated by the oblique fissure.-10 bronchopulmonary segments

ANATOMY IN A HEALTHY LUNG

Bronchopulmonary segments

The main anatomy affected by pleural effusions are the layers in the Lung

There are two layers-the parietal pleura and the visceral pleura.

• At the Hilum, the parietal pleura folds back on itself to become the visceral pleura.

The pleural fluid contains –-contains about 5-15ml of fluid at one time -about 100-200ml of fluid circulates though the pleural space within a 24-hour period -has an alkaline pH of about 7.60 - 7.64

Protein content less than 2% (1-2 g/dL) Glucose content similar to that of plasma Mesothelial cells Macrophages Lymphocytes (few) Sodium, potassium and calcium concentrations similar to that of interstitial fluid. Lactate Dehydrogenase concentration of less than 50% of that of plasma

ANATOMY OF A HEALTHY LUNG

A pleural effusion is an accumulation of fluid between the parietal pleura and the visceral pleura.

Chest X-ray frontal view: 100-200ml pleural fluid

ANATOMY OF A LUNG WITH A PLEURAL EFFUSION

Recesses of Pleura

ANATOMY & PHYSIOLOGY OF A LUNG WITH A PLEURAL EFFUSION

• The fluid accumulates due to the over production of pleural fluid by the mesothelial cells and separates the visceral and parietal pleura.

• This fluid can not be drained by the lymphatic system, and so therefore continues to accumulate, resulting in a pleural effusion.

• The accumulation of fluid may also be due to changes in hydrostatic pressure or oncotic pressure.

The lung has the natural tendency to collapse towards the hilum and this is

opposed by forces of similar magnitude in the chest wall tending to expand

outward. Thus the parietal and visceral pleura are kept in close apposition. If

increase fluid or air collect in the pleural space ,the effect of outward forces on the

underlying lung is diminished, and the lung tend to retract toward its hilum.

Aetiology

There are 4 different fluids which can accumulate in the pleural space.

• Blood HAEMOTHORAX• Pus EMPYEMA• Chyle CHYLOTHORAX• Serous fluid HYDROTHORAX

• They can further be classified into TRANSUDATES and EXUDATES depending on – Chemical composition– Mechanism of fluid formation

Light’s criteria: Transudate vs. Exudate•

Pleural fluid protein / serum protein > 0.5Pleural fluid LDH / serum LDH > 0.6Pleural fluid LDH > 2/3 ULN serum LDH

Pathophysiology

Hydrostatic Pressure

Oncotic pressure

Increased peritoneal fluid

Mechanisms for pleural fluid accumulation:

• Increased hydrostatic pressure (Eg. CCF)

• Reduced plasma oncotic pressure (Eg. Hypoproteinaemia)

• Increased capillary permeability (Eg.TB, Tumour )

• Reduced lymphatic drainage from pleural space (Obstrustioin by tumour, TB, radiation)

• Transdiaphragmatic passage of fluid (Eg. Liver disease, Acute pancreatitis) .

Transudates• Clear, pale yellow, watery substance• Increase hydrostatic pressure, • Decrease oncotic pressure

• Common causes: Congestive heart failure Cirrhosis of the Liver Nephrotic syndrome Hypoproteinaemia Hypothyroidism Acute rheumatic fever

Exudates• Pale yellow and cloudy substance, has a low pH• Influenced by local factors where fluid absorption is

altered (inflammation, infection, cancer) • Rich in white blood cells.

• Common causes: Pulmonary TB Pneumonia Bronchial carcinoma Pulmonary infarction Collagen disease (SLE, RA) Lymphoma Meig’s syndrome (Right pleural effusion, Ascites, Ovarian fibroma)

Blood stained fluidTends to loculate earlyCT scan shows higher density measurement

Common causes:-Chest injury -Bronchial carcinoma-Pulmonary infarction -Lymphoma

Haemothorax

Chylothorax• Milky fluid due to lymph and fats• Chyle leaks from the thoracic duct due to -damage to the lymphatic vessels. -lymphatic obstruction (tumor) or trauma• High triglyceride levels found in fluid analysis• Common causes:

• Traumatic (thoracic surgery), trauma to thoracic duct• Neoplastic ( Bronchial carcinoma, metastasis)• Infective (TB)• Lymphoma (involving thoracic duct)

Empyema• Pus in pleural space • Yellow, cloudy, and foul odor• Has a pH > 7.2

• Common causes:

Pneumonia Rupture of lung abscess, Rupture of sub-phrenic abscess Tuberculosis Infected chest wounds Secondary infection during aspiration of pleural fluid

Diagnosis of Pleural Effusions

• Medical history• Physical examination

• Plain film chest x-ray – first line imaging• CT• Ultrasound imaging

Diagnosing Pleural Effusions through Imaging

Characteristics on a supine chest radiograph

• Fluid accumulates posteriorly• Affected hemi-thorax appears whiter or

paler grey

• Apparent thickening of the pleura• Approx 200 mls of fluid present before

abnormal pale grey appearance is produced

First line imaging – Chest x-ray

Clear right side hemi-diaphragmand sharpcostophrenic angle

Area of homogenousWhiteness, with loss of hemi-diaphragm

Meniscus shaped upper border

Features on a PA or AP erect radiograph

A large right side pleural effusion

The hearthas been pushed towardsthe left side by the fluid

Entire white-out of right hemi-thorax

Lateral decubitus chest radiograph

Free layering pleural effusion

At least 100mlpleural fluid isnecessary

Laminar Pleural effusion

Subpulmonic effusion

Loculated fluid

Loculated effusion (elliptical, pointed margins)

in left major fissureCT Scan

Pleural Effusion Diagnosis through CT Imaging

Aorta

Left Lung

Heart

Right Lung

Ribs

Crescent-shaped pleural effusion

Aorta

Mass, right upper lobe

Irregular soft-tissue thickening

Pleural effusion

Ascites

Right Lung

Pleural effusion

SpleenDiaphragm

Liver

CT signs:Pleural effusion vs ascites.

4 signs 1.Displaced crus sign:Pleural fluid may collect posterior to the diaphragmatic crux and therefore displace the crus anteriorly, whereas ascites collects anterior to the crus and may cause posterior displacement.

2.Diaphragm sign:As an extension of the displaced crus sign,Any fluid that is on the exterior of the dome of the diaphragms in the pleura, whereas any that is within the dome is ascites

3.Interface sign: The interface between the liver or spleen & pleural fluid is said to be less sharpthan that between the liver or spleen and ascites

4.Bare area sign:The peritoneal coronary ligament prevents ascitic fluid from extending over the entire posterior surface of the liver, whereas in a free pleural space, pleural fluid may extend or over the entire posterior costophrenic recess behind the liver

Ultrasound• No radiation, • Small effusions missed on CXR• Even 20-25 ml of fluid can be detected• Transudate-Anechoic, Exudative- Reflectative +/-• Identify pleural thickening and masses • Used to guide thoracocentisis

Patient position• Patient seated, arms folded, leaning

forward

• Unwell patient imaged semi-supine

MRI• Not used to image pleural effusion• Incidental finding

Treatment • Needed if patient becomes breathless• Small effusions are left and ‘observed’

• Usually directed at underlying cause (antibiotics for pneumonia)

• Underlying cause treated effusion will go away for good

• If not it will return within few weeks

Thoracocentisis• Invasive procedure• Removes fluid from pleural space• Allows lung to expand, making breathing easier• Guided using ultrasound

Pleurodesis• Chemical inserted into pleural space• Parietal and visceral layers become irritated• Closes space• Painful

Pleuroperitoneal Shunt• Internal shunt• Fluid drains from chest into abdominal cavity

Pleurectomy• Operation to remove the pleura• Most severe cases

Have a nice day

Nepal