What is Thoracentesis?

Thoracentesis Procedure Video

Thoracentesis is a procedure in which a needle is inserted into the pleural space to remove fluid or air, biopsy the pleura, or instill medications into the pleural space.

Pleural Effusion Causes

The pleural space, or pleural cavity, is the tiny area outside of the lungs and inside of the chest wall. It is between the visceral pleura (which covers the lungs) and the parietal pleura (which is attached to the chest wall). There is a lubricating fluid inside the pleural cavity that allows for smooth inhalation and exhalation of the lungs.

What causes pleural effusion, or the buildup of fluid in the pleural cavity, leading to the need for thoracentesis?

There could be conditions in which the body is not handling fluid properly, such as:

   Congestive heart failure - most common cause of pleural effusion.
Kidney or liver disease

Also, inflammation from:

Bacterial, viral, or fungal infections
Lupus and other autoimmune diseases

And there are other causes including:

Pulmonary embolism
Pulmonary hypertension

Procedure Steps

The procedure for a thoracentesis involves the following steps:
1. Explain the procedure & obtain a signed consent form. Emphasize the importance of not moving or coughing & breathing quietly during the procedure.

2. Assess patient’s respiratory status & vital signs, including pulse oximetry.

3. Position the patient upright with their arms & head resting on a bedside table with a pillow. If the patient is unable to sit, they may be placed in a side-lying position on the edge of the bed on the unaffected side. The thoracentesis needle is usually inserted in the back, over the diaphragm, but under the area of fluid.

4. Sterile technique is used, including gloves, antiseptic prep and drapes.

5. During the procedure, monitor vital signs & respiratory status. Monitor for increased shortness of breath, hypoxemia, tracheal deviation (signs of pneumothorax), hypotension, bloody sputum, & vasovagal reflex. Up to 1 L of fluid may be removed.

6. At the end of the procedure, a small sterile dressing should be placed over the puncture site. Vital signs should be monitored & a chest x-ray may be done to detect possible pneumothorax.

The primary risks of thoracentesis include:

Pneumothorax – This is an abnormal collection of air in the pleural space, which could be caused by air coming in through the needle, or the needle making a hole in the lung. If enough air gets into the pleural space, the lung can collapse, which may require a chest tube. To help prevent a pneumothorax, it is important that less than 1500 mL of fluid be removed at one time. If the fluid is completely drained at one time, needle laceration of the visceral pleura (& lung) is more likely to occur.

Hypovolemic shock (due to a lack of circulating fluid volume) can occur when more than 1,000 mL of fluid is withdrawn. This causes syncope (fainting) and shock, therefore, monitor the patient’s VS immediately after the procedure & every 15 minutes until readings are stable.

Another risk is Pulmonary edema (fluid in the lungs)

Pain, bruising, bleeding, or infection where the needle was inserted may occur.

Though a rare occurrence, liver or spleen injury can occur with needle insertion.

After the procedure, teach the patient to avoid strenuous activity for a few days and call their healthcare provider if they have any of the following:

    Fever of 100.4 F or higher
Needle site has redness or swelling, or has blood or
other fluid leaking from site.
Shortness of breath
Difficulty breathing
Chest pain


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by Mometrix Test Preparation | Last Updated: January 30, 2024