Pleural Effusion

Question 1

Definition

Answer 1

Pleural effusion is the abnormal accumulation of fluid in the pleural space, i.e., between the visceral and parietal pleura

Question 2

Introduction

Answer 2

Fluid in the pleural space which could be pus, blood or lymph
It is a potential space measuring about 10-24 um
It contains a colourless alkaline fluid & low protein
Pleurisy: inflammation of the pleura

The most common cause in children is bacterial pneumonia
-Other causes: heart failure, TB, rheumatologic and metastatic intrathoracic diseases.

Males and females are equally affected

Non-bacterial (viral) causes are commoner in younger children
Though most are acquired, pleural effusion could be congenital
Seen in downs syndrome, polyhydramnios, hydrops fetalis, pulmonary hypoplasia & diaphragmatic hernia
Viral and mycoplasma causes may resolve spontaneously

Malignant effusion has a worse prognosis

Question 3

The pleura fluid

Answer 3

Could be
1. exudative
2. or transudative, based on the protein content

3. It may contain lymph or fats (chylothorax)
   -Defined as pleural lipid of 1-4g/dl
4. It may contain blood (haemothorax)
   Defined as pleural PCV >50% of peripheral blood PCV
5. It may contain pus (empyema)
   -Defined as the presence of dead neutrophils (polymorphs) in the pleural space

Question 4

Aetiology

Answer 4

1. Exudative pleural effusion
   -infections, left-sided pancreatitis, CTDs, chylothorax, malignancies & trauma
2. Transudative pleural effusion
   -CCF, hypoalbuminaemia, nephrosis, hepatic cirrhosis,
   -Iatrogenic such as misplaced central lines & complications of VP shunts

Haemorrghagic effusion
-Trauma, malignancy, vascular erosions & coagulopathy

Question 5

Pathogenesis

Answer 5

Pleural fluid originates from capillaries of the parietal pleura
It is regulated by a balance of production and absorption
Production is from the capillaries.
Normally, about 4-12 mls (0.1-0.2 mls/kg) of fluid is present in the pleural space
Absorption is from pleural veins, openings and lymphatics
90% of pleural fluid is drained by veins
Parietal pleura drain to the anterior & posterior chest wall openings
Visceral drain to mediastinal nodes
Chest & diaphragmatic movements enhance absorption
Increased pleural fluid results from increased production, reduced absorption and obstruction

Pleural inflammation
-increases the permeability of pleural surfaces
-Results in high protein fluid
-Follows Starlings’ law: balance of hydrostatic and oncotic pressure)

Question 6

CLASSIFICATION

Answer 6

Transudative effusion
Exudative effusion
Empyema (pus)
Chylothorax
Hemothorax

Transudates

-occur bilaterally & due to diseases that affect filtration such as heart failure, nephritis etc

Exudates are usually unilateral & due to increased permeability to proteins.
-They usually follow inflammation or injury

Question 7

Types

Answer 7

Based on the inflammatory processes involved

3 types

-Dry or plastic

-Serofibrinous or serosanguineous

-Purulent or empyema

Question 8

DRY PLURISY

Answer 8

Limited to viscera pleura

Small amounts of yellow serous fluid

Adhesions between pleural surfaces

Develops rapidly in TB with thickened pleura

Markedly reduces lung excursion due to fibrothorax
Associations

-acute bacterial or viral pulmonary infections

-URTI, TB and CTDS