Thoracocentesis (Pleural Tap)

Indications

A. Diagnostic Thoracocentesis

Indications

• New pleural effusion of unknown etiology
• Effusion associated with:
• Fever
• Sepsis
• Respiratory deterioration
• Suspicion of:
• Tuberculosis
• Malignancy
• Parapneumonic effusion
• Empyema
• Chylothorax

Diagnostic thoracocentesis yields clinically useful information in >90% of cases. 

When Thoracocentesis May NOT Be Required

Small bilateral effusions with a classic congestive heart failure (CHF) picture responding rapidly to diuretics.

Persistent Undiagnosed Exudate

If exudative pleural effusion remains undiagnosed after thoracocentesis:

• Ultrasound-guided pleural biopsy
• Medical thoracoscopy/VATS
  may be required. Thoracoscopy has diagnostic yield >80%. 

B. Therapeutic Thoracocentesis

Performed to relieve symptoms or prevent complications.

Indications

• Moderate–large pleural effusion causing:
• Dyspnea
• Hypoxia
• Lung compression
• Tense pleural effusion
• Cardiac tamponade effect from massive effusion
• Empyema (initial decompression)
• Malignant pleural effusion
• Loculated pleural effusion
• Tension pneumothorax (needle decompression/catheter drainage) 

Contraindications

Absolute Contraindications

True Absolute Contraindication

• Uncooperative patient with inability to remain still
• Sudden movement may cause lung or vascular injury. 

Practically No Absolute Contraindication in Emergencies

Life-saving thoracocentesis should proceed in severe respiratory compromise.

Relative Contraindications

• Severe thrombocytopenia plt<20k
• Severe coagulopathy INR>3
• Local skin infection
• Chest wall malignancy at puncture site
• Bullous emphysema

Many previously considered contraindications are no longer absolute if ultrasound guidance is used. 

Coagulopathy Evidence

Large studies show no significantly increased bleeding risk in patients with:

• Coagulopathy
• Thrombocytopenia
  when ultrasound guidance is used. 

Classical Landmark Technique

Patient Position

• Sitting upright
• Leaning forward

Traditional Site

• 7th–9th intercostal space(never below it)
• Posterior axillary One or two intercostal spaces below upper fluid level

 Landmark-only thoracocentesis is obsolete in ICU practice where ultrasound is available. 

Preferred Ultrasound Probes

• Phased-array probe (3.5–5 MHz) → preferred
• Curvilinear probe → acceptable
• Linear probe → useful for superficial localization/intercostal vessels

Ultrasound Findings of Pleural Effusion

Basic Appearance

• Anechoic/hypoechoic dependent space

Dynamic Signs

• Floating atelectatic lung
• Respiratory movement
• Septations in complicated effusion
• Swirling echoes in hemothorax/empyema

Essential Structures to Identify

• Chest wall,Lung,Diaphragm,Liver/spleen,Kidney

 Failure to identify diaphragm may result in hepatic/splenic puncture.

Color Doppler Use

Useful to identify aberrant intercostal vessels and reduce hemothorax risk. 

Pre-Procedure Checklist 

Consent Explain Risks

• Pain
• Pneumothorax
• Bleeding
• Infection
• Vasovagal episode
• Re-expansion pulmonary edema (REPE)

Equipment

• 1–2% lignocaine
• 10–20 mL syringe
• 20–22 G needle
• 21G spinal needle in obese patients
• Catheter-over-needle kit (preferred for large drainage)
• 3-way stopcock
• Vacuum bottle or drainage tubing
• Pleural fluid bottles:
• EDTA
• Sterile culture bottle
• Plain container
• Pleural manometer (if available)

Standard Position

• Sitting upright
• Leaning forward over pillow/table

ICU Alternatives

• Semirecumbent
• Lateral decubitus
• Supine with ipsilateral arm abducted

Assistant should stabilize patient to avoid sudden movement. 

Pain occurs when parietal pleura is infiltrated.

Do NOT inject lignocaine into pleural fluid:

• It is bactericidal
• May interfere with microbiological diagnosis including TB. 

Step 4: Needle Insertion Just above rib

• Advance gradually while aspirating continuously
• Feel characteristic “give-way” when pleura breached

 Continuous aspiration helps avoid vascular puncture.

Diagnostic Thoracocentesis

• Usually 20–50 mL sufficient

Therapeutic Thoracocentesis

Recommended maximum:1–1.5 L per sitting

Stop Procedure If

• Persistent cough
• Chest pain
• Dyspnea
• Vasovagal symptoms
• Hypoxia
• Ipsilateral anterior chest discomfort
• Suggests non-expandable lung. 

Drainage Method-Manual syringe drainage preferred over vacuum suction because:

• Faster than gravity drainage
• Less discomfort than vacuum-assisted drainage 

Removal Technique

Remove during: Exhalation OR Humming/Valsalva maneuver

Pleural Fluid Analysis

Light’s Criteria

Exudate if ANY ONE present:

Additional Pleural Fluid Tests

Important Pleural Fluid Studies

• Cell count & differential
• Gram stain
• Culture
• AFB smear/culture
• Fungal culture
• Cytology
• Flow cytometry
• PCR/NAAT

Re-Expansion Pulmonary Edema (REPE)

Rapid lung re-expansion causes:

• Increased capillary permeability
• Pulmonary edema

Clinical Features

• Persistent cough
• Chest tightness
• Dyspnea
• Hypoxia
• Pink frothy sputum (rare)

Ultrasound Findings

• New unilateral B-lines
• Alveolar consolidation 

 Complications

Routine post-procedure CXR is NOT mandatory if:

• Ultrasound-guided
• Patient asymptomatic
• Lung sliding documented post-procedure