Etiology
The development of pleural inflammation is provoked by multiple factors. The main etiological groups include:
- Infections: inflammation can be caused by bacteria (against the background of pneumonia), Mycobacterium tuberculosis, as well as viruses, fungi, parasites, and atypical flora (Chlamydia, Mycoplasma, Legionella, Rickettsia).
- Oncology: primary lung and pleural tumors (mesothelioma), metastases, as well as malignant blood diseases (leukemias, lymphomas), and Kaposi sarcoma.
- Systemic connective tissue diseases: inflammation develops as part of polyserositis in rheumatism, rheumatoid arthritis, scleroderma, or systemic lupus erythematosus (SLE).
- Trauma and mechanical injuries: disruption of the integrity of the leaves leads to the accumulation of air (pneumothorax), blood (hemothorax), or lymph (chylothorax) in the cavity.
- Vascular catastrophes: for example, a subpleurally located pulmonary infarction in pulmonary embolism.
Differential diagnosis of effusion
The accumulation of fluid in the pleural cavity is a frequent syndrome. It is extremely important to distinguish between two types of fluid, as this indicates the cause of the pathology.
1. Exudate (inflammatory) Formed directly due to inflammation of the pleura itself. It can be an independent disease or a reaction to lung pathology and systemic processes (polyserositis).
2. Transudate (non-inflammatory) Accumulates due to a violation of the physical laws of fluid exchange in the body, rather than due to inflammation of the leaves:
- Increased hydrostatic pressure: occurs with blood congestion (typical for heart failure).
- Decreased oncotic pressure: associated with a lack of plasma proteins (hypoalbuminemia). It occurs in liver cirrhosis, nephrotic syndrome, malabsorption syndrome.
Pathogenesis and impact on respiration
Any fluid (exudate or transudate) occupies volume in the closed thoracic cavity, triggering a number of mechanical problems:
- The lung tissue is compressed by the fluid and collapses, forming compression atelectasis.
- The normal biomechanics of respiration are impaired (the lung physically cannot expand during inspiration).
- If the effusion is massive, it displaces the mediastinal organs to the opposite (healthy) side.
- As a result, restrictive respiratory failure develops.
Clinical presentation
Disease manifestations heavily depend on the stage and presence of effusion.
Dry (fibrinous) pleurisy Always begins acutely. The patient is bothered by severe, stabbing pain that radiates to the shoulder or epigastrium. The pain sharply increases with coughing or an attempt to take a deep breath. To reduce suffering, the patient tries to immobilize the chest or lies on the affected side. Upon examination, the affected side lags in respiration due to reflex guarding.
Exudative (effusive) pleurisy Develops more gradually (often as a continuation of the dry stage). Pain takes a back seat. The lagging of the affected half of the chest in respiration persists, but now due to a mechanical barrier—the accumulation of fluid. Upon examination, percussion and auscultatory signs of fluid in the pleural cavity will be detected.
Principles of treatment
The basis of therapy is etiotropic treatment, i.e., elimination of the root cause. First, the underlying disease must be treated (pneumonia, tuberculosis, rheumatism, SLE).
To relieve symptoms and reduce inflammation, pathogenetic and symptomatic agents are used—nonsteroidal anti-inflammatory drugs (NSAIDs) such as acetylsalicylic acid or phenylbutazone.
With significant effusion, thoracentesis (chest puncture) is resorted to. This invasive intervention serves two purposes: mechanical removal of inflammatory fluid to ease breathing and local administration of medications (e.g., antibiotics).
Briefly: answers to topical questions
What percussion signs are characteristic of exudative pleurisy?
Exudative pleurisy is characterized by the appearance of a dull percussion sound and specific topographic zones.
- Dullness — determined directly over the effusion area (shortening of the percussion sound, absolutely dull or femoral sound).
- Damoisseau's line (Ellis-Damoisseau-Sokolov line) — the oblique upper border of dullness, running from inferior-lateral to superior-medial with the highest point along the axillary lines.
- Garland's triangle — a zone of tympanites (dull-tympanic shade) above Damoisseau's line, caused by the compressed lung.
- Rauchfuss-Grocco triangle — an area of dullness on the healthy side near the spine, arising due to mediastinal shift.
There is also a significant limitation of the mobility of the lower lung margin.
What auscultatory changes are determined over the pleural effusion area?
Over the pleural effusion area, auscultation reveals significant weakening or complete absence of respiratory sounds.
The following changes are auscultated:
- Weakened or absent breath sounds — determined directly over the fluid accumulation zone / dullness zone.
- Bronchial breathing — may be auscultated above the fluid level, which is associated with compression atelectasis.
- Pleural friction rub — may be auscultated along the upper border of the effusion.
What laboratory tests and criteria are used for the differential diagnosis of exudate and transudate?
Analysis of the pleural fluid is used for the differential diagnosis of transudate and exudate.
| Parameter | Transudate | Exudate |
|---|---|---|
| Rivalta's test | Negative | Positive |
| Glucose | Normal | Decreased (in purulent conditions, tuberculosis, tumors) |
During differential diagnosis, the following pleural fluid criteria are also evaluated:
- Relative density (threshold value 1018).
- Protein (level 30 g/L).
- Pleural fluid protein / blood protein ratio (level 0.5).
- Pleural fluid LDH / blood LDH ratio (level 0.6).
- Cytosis (level 1000).
Additionally, cytologic examination, bacterioscopy, culture, and pH determination are performed.
Class and exam questions
What is the difference between transudate and exudate?
Exudate is a consequence of local pleural inflammation, while transudate accumulates due to systemic disorders (heart failure, protein deficiency) in which the pleural leaves themselves are not inflamed.
Why does a patient with dry pleurisy lie on the affected side?
This is a forced position. Lying on the affected side, the patient limits the mobility of the inflamed pleura (immobilizes the chest), which significantly reduces pain.
Why is thoracentesis performed in pleurisy?
The puncture is performed to drain excess fluid (relieve the lung from compression) and, if necessary, administer medications, such as antibiotics, directly into the focus of inflammation.
What type of respiratory failure is characteristic of pleural effusion?
Restrictive respiratory failure develops because the fluid limits the lung's ability to fully expand during inspiration.
What else to study on this topic
- Percussion and auscultatory phenomena during fluid accumulation
- Mechanism of compression atelectasis development
- The concept of polyserositis and its connection with systemic diseases
- Characteristics of pain syndrome and radiation in dry pleurisy
- Detailed algorithm for the differential diagnosis of transudate and exudate based on laboratory parameters
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