Thoracentesis

Thoracentesis /ˌθɔːrəsɪnˈtiːsɪs/, also known as thoracocentesis (from Greek θώραξ (thōrax, GEN thōrakos) 'chest, thorax', and κέντησις (kentēsis) 'pricking, puncture'), pleural tap, needle thoracostomy, or needle decompression (often used term), is an invasive medical procedure to remove fluid or air from the pleural space for diagnostic or therapeutic purposes. A cannula, or hollow needle, is carefully introduced into the thorax, generally after administration of local anesthesia. The procedure was first performed by Morrill Wyman in 1850 and then described by Henry Ingersoll Bowditch in 1852.^[1]

The recommended location varies depending upon the source. Some sources recommend the

Tension pneumothorax is a medical emergency that requires needle decompression before a chest tube is placed.^[6][7]

Indications

This procedure is indicated when unexplained fluid accumulates in the chest cavity outside the lung. In more than 90% of cases analysis of pleural fluid yields clinically useful information. If a large amount of fluid is present, then this procedure can also be used therapeutically to remove that fluid and improve patient comfort and lung function.

The most common causes of pleural

An uncooperative patient or a coagulation disorder that cannot be corrected are relative contraindications.^[9] Routine measurement of coagulation profiles is generally not indicated, however; when performed by an experienced operator "hemorrhagic complications are infrequent after ultrasound-guided thoracentesis, and attempting to correct an abnormal INR or platelet level before the procedure is unlikely to confer any benefit".^[10]

Relative contraindications include cases in which the site of insertion has known

Major complications are pneumothorax (3–30%), hemopneumothorax, hemorrhage, hypotension (low blood pressure due to a vasovagal response) and reexpansion pulmonary edema.

Minor complications include a dry tap (no fluid return), subcutaneous

The use of ultrasound for needle guidance can minimize the complication rate.^[3][4][5]

Follow-up imaging

While chest X-ray has traditionally been performed to assess for pneumothorax following the procedure, it may no longer be necessary to do so in asymptomatic, non-ventilated persons given the widespread use of ultrasound to guide this procedure.^[11]

Interpretation of pleural fluid analysis

Several diagnostic tools are available to determine the etiology of pleural fluid.

Transudate versus exudate

First the fluid is either transudate or exudate.

An exudate is defined as pleural fluid to serum total protein ratio of more than 0.5, pleural fluid to serum LDH ratio > 0.6, and absolute pleural fluid LDH > 200 IU or > 2⁄3 of the normal.

An exudate is defined as pleural fluid that filters from the circulatory system into lesions or areas of inflammation. Its composition varies but generally includes water and the dissolved solutes of the main circulatory fluid such as blood. In the case of blood it will contain some or all plasma proteins, white blood cells, platelets and (in the case of local vascular damage) red blood cells.

Exudate

• hemorrhage
• Infection
• Inflammation
• Malignancy
• Iatrogenic
• Connective tissue disease
• Endocrine disorders
• Lymphatic disorders vs Constrictive pericarditis

Transudate

• Congestive heart failure
• Nephrotic syndrome
• Hypoalbuminemia
• Cirrhosis
• Atelectasis
• Trapped lung
• Peritoneal dialysis
• Superior vena cava obstruction

Amylase

A high amylase level (twice the serum level or the absolute value is greater than 160 Somogy units) in the pleural fluid is indicative of either acute or chronic pancreatitis, pancreatic pseudocyst that has dissected or ruptured into the pleural space, cancer or esophageal rupture.

Glucose

Glucose is considered low if pleural fluid value is less than 50% of normal serum value. The differential diagnosis for this is:

• rheumatoid effusion. The levels are characteristically low (<15 mg/dL).
• lupus
  effusion
• bacterial empyema
• malignancy
• tuberculosis
• esophageal rupture (
  Boerhaave syndrome
  )

pH

Normal pleural fluid pH is approximately 7.60. A pleural fluid pH below 7.30 with normal arterial blood pH has the same differential diagnosis as low pleural fluid glucose.

Triglyceride and cholesterol

The main cause for chylothorax is rupture of the thoracic duct, most frequently as a result of trauma or malignancy (such as lymphoma).

Cell count and differential

The number of

Cultures and stains

If the effusion is caused by