Pleural Effusion Nursing Guide

Definition & Types

A pleural effusion is an abnormal accumulation of fluid in the pleural space (between the visceral and parietal pleura). Normal pleural fluid volume: ~0.2 mL/kg (10–20 mL total). Effusions are classified as transudates or exudates based on fluid protein and LDH content.

Transudate

Low protein fluid from systemic pressure/osmotic disturbance.

Causes:

Heart failure ⭐ (most common)
Liver cirrhosis / hypoalbuminaemia
Nephrotic syndrome
Hypothyroidism
Constrictive pericarditis

Exudate

High protein fluid from pleural/lung inflammation or reduced drainage.

Causes:

Pneumonia / parapneumonic effusion ⭐
Malignancy (lung, breast, lymphoma, mesothelioma)
Tuberculosis (common in GCC expat populations)
Pulmonary embolism
Rheumatoid arthritis, SLE
Pancreatitis

Heart failure + bilateral effusions = transudate. Unilateral effusion = more likely exudate (malignancy, TB, pneumonia) — warrants thoracocentesis and cytology.

Clinical Features

Symptoms

Dyspnoea (proportional to effusion size)
Pleuritic chest pain (if inflammatory aetiology)
Dry cough
Reduced exercise tolerance

Examination Findings (CLASSIC TRIAD)

Dullness to percussion over the effusion
Reduced/absent breath sounds over the effusion
Reduced/absent vocal resonance (whispered pectoriloquy absent)
Tracheal deviation away from massive effusion (mediastinal shift)
Egophony ("E" to "A" change) at fluid level

Tracheal deviation TOWARD effusion = collapse. Deviation AWAY = tension pneumothorax or massive effusion.

Light's Criteria — Exudate vs Transudate

The definitive method to classify pleural fluid — analysed from fluid obtained by thoracocentesis. If ANY of the following 3 criteria are met, the fluid is an exudate.

Criterion 1

Pleural protein / Serum protein ratio > 0.5

Exudate: protein-rich from inflammation/malignancy

Criterion 2

Pleural LDH / Serum LDH ratio > 0.6

LDH reflects cellular damage and inflammation

Criterion 3

Pleural LDH > 2/3 upper normal serum LDH

Usually > 200 IU/L (institution-specific normal range)

Mnemonic — Light's: P-L-L (Protein, LDH ratio, LDH absolute)
If ANY one criterion is met → Exudate → investigate further (cytology, culture, adenosine deaminase for TB).

Additional Fluid Analysis

Test	Significance
pH < 7.20	Empyema or malignancy — drain required urgently
Glucose < 3.3 mmol/L	Empyema, malignancy, rheumatoid
Amylase elevated	Pancreatitis-related effusion, oesophageal rupture
Adenosine deaminase (ADA) > 40 IU/L	Tuberculosis effusion (sensitivity 90%+)
Cytology	Malignant cells — diagnoses malignant effusion
Culture and sensitivity	Parapneumonic/empyema — guide antibiotics
Triglycerides > 1.24 mmol/L	Chylothorax (thoracic duct injury)
Haematocrit > 50% of blood	Haemothorax

Investigations for Pleural Effusion

Investigation	Purpose / Findings
CXR (PA)	Detects effusions >200 mL; blunting of costophrenic angle; white-out; tracheal deviation
Ultrasound (bedside)	Most sensitive; confirms effusion, guides safe aspiration site; distinguishes free vs loculated
CT chest with contrast	Underlying malignancy, pleural thickening, empyema; guides thoracocentesis for complex effusions
Thoracocentesis (diagnostic)	Light's criteria; cytology; culture; ADA
BNP/NT-proBNP (serum)	High = cardiac cause (transudate from heart failure)
Echo (cardiac)	LV dysfunction, pericardial effusion, valvular disease

Management

Transudate — Treat Underlying Cause

Heart failure: diuretics (furosemide), optimise cardiac function
Hypoalbuminaemia: nutritional support; treat underlying liver/renal disease
Hypothyroidism: levothyroxine
Therapeutic drainage only if symptomatic and refractory to medical treatment

Exudate — Targeted Treatment + Drainage

Parapneumonic: antibiotics; drain if pH <7.2 or loculated
Empyema: chest drain (large bore) + IV antibiotics + fibrinolytics if loculated
Malignant: consider pleurodesis (talc) for recurrent symptomatic effusion; indwelling pleural catheter (IPC) for palliation
TB: antituberculous therapy; steroids may reduce pleural thickening

Thoracocentesis (Pleural Aspiration) — Nursing Role

Confirm consent and site with ultrasound before procedure
Position: sitting upright, leaning forward on pillow ("prayer position") — opens intercostal spaces
Baseline obs: SpO₂, BP, HR, RR
Needle inserted over upper border of rib (to avoid intercostal vessels and nerve which run along lower border — VAN: Vein Artery Nerve)
Maximum single aspiration: 1500 mL at one sitting (risk of re-expansion pulmonary oedema)
Post-procedure CXR to exclude pneumothorax
Monitor for complications: cough, dyspnoea, pain (pneumothorax), vasovagal episode

Re-expansion pulmonary oedema: If the lung re-expands rapidly after large volume drainage (especially if lung collapsed for >1 week), flash pulmonary oedema can occur. Maximum 1500 mL drainage at one sitting. Stop if patient develops cough, dyspnoea, or chest tightness.

Chest Drain Management (Intercostal Drain)

Position: lateral decubitus or sitting, axillary approach for large effusions
Water seal: ensure water seal bubbles with respiration (drainage patent)
Drain output: document hourly; rapid drainage >200 mL/hr suggests haemothorax — escalate
Never clamp drain in empyema (risk of tension)
Removal: when drainage <150 mL/24 hours and CXR confirms adequate drainage

GCC-Specific Pleural Effusion Context

Tuberculosis effusion — TB is a significant cause of exudative pleural effusion in GCC countries given the large expat workforce from high-TB-burden countries (South Asia, East Africa, Philippines). ADA >40 IU/L in pleural fluid strongly suggests TB. Nucleic acid amplification (NAAT/GeneXpert) of pleural biopsy has higher sensitivity than fluid alone.
Mesothelioma — historically seen in some GCC workers with occupational asbestos exposure (ship-building in Bahrain, construction). Unilateral exudative effusion in older male workers with occupational history warrants CT and pleural biopsy.
Cardiac failure effusions — high prevalence of hypertension, diabetes, and ischaemic heart disease in GCC patients means cardiac failure effusions are very common. Typically bilateral, respond to diuretics; BNP helpful for differentiation.
Lung cancer effusions — rising lung cancer rates in GCC (historically low due to lower smoking rates, but increasing with lifestyle change and shisha use). Malignant effusions are exudates; cytology positive in ~60% of malignant effusions.

MCQ Practice — Pleural Effusion

Q1. A pleural fluid analysis shows: pleural protein/serum protein ratio 0.6, pleural LDH/serum LDH ratio 0.7, pleural LDH 280 IU/L. How is this fluid classified?

A) Transudate — no further investigation needed

B) Exudate — all three Light's criteria are met

C) Chylothorax — send triglycerides

D) Haemothorax — send haematocrit

✅ B — All 3 Light's criteria met: protein ratio >0.5 ✓, LDH ratio >0.6 ✓, LDH >2/3 upper limit ✓. Any ONE criterion makes it an exudate. Causes: pneumonia, malignancy, TB, PE.

Q2. An adenosine deaminase (ADA) level >40 IU/L in pleural fluid most strongly suggests which aetiology?

A) Malignant pleural effusion

B) Cardiac failure

C) Tuberculous pleural effusion

D) Chylothorax

✅ C — ADA is produced by lymphocytes and is markedly elevated in TB pleural effusion (sensitivity ~90%). Particularly useful in GCC settings where TB is common in South Asian and East African expat populations. A negative ADA largely excludes TB effusion.

Q3. What is the maximum volume of pleural fluid that should be drained in a single thoracocentesis session to prevent re-expansion pulmonary oedema?

A) 500 mL

B) 1000 mL

C) 1500 mL

D) No limit if tolerated well

✅ C — Maximum single aspiration is 1500 mL to reduce the risk of re-expansion pulmonary oedema (flash pulmonary oedema). Stop if dyspnoea, chest pain, or persistent cough develops during drainage.

Q4. During thoracocentesis, the needle is inserted along which border of the rib and why?

A) Lower border — more accessible approach

B) Upper border — to avoid the intercostal neurovascular bundle (Vein, Artery, Nerve)

C) Middle of the intercostal space — equidistant from both structures

D) Lower border — the vein is protected by the rib inferiorly

✅ B — The intercostal neurovascular bundle (Vein, Artery, Nerve — VAN) runs along the inferior border of each rib. Needle insertion along the UPPER border of the rib below the targeted intercostal space avoids damaging these structures. This is a fundamental surgical anatomy principle.

Pleural Effusion — Nursing Guide