A chest tube is a flexible catheter inserted into the pleural space, the area between the lung and the chest wall. Its purpose is to restore normal lung function by draining unwanted air or fluid from this area. Removing these substances re-establishes the necessary negative pressure in the pleural space, allowing the lung to fully expand and function properly.
Conditions Requiring a Chest Tube
Normal breathing requires negative pressure in the pleural space to keep the lung inflated. This balance is disrupted when air or fluid accumulates, preventing the lung from expanding fully. A pneumothorax (collapsed lung) occurs when air enters the pleural space, compressing the lung tissue. Other conditions include hemothorax (buildup of blood, often from trauma) or pleural effusion (accumulation of other excess fluid). The chest tube removes these substances, relieving pressure and enabling the lung to re-inflate.
The Insertion Process
The procedure for placing a chest tube, known as a thoracostomy, is often performed at the patient’s bedside. It begins with administering a local anesthetic to numb the skin and deeper tissues between the ribs. A small incision is made, usually between the fourth or fifth ribs, and the clinician guides the tube into the pleural space. The tube’s position depends on what is being drained: superiorly for air, or inferiorly for fluid. Once placed, the tube is secured to the skin with sutures and covered with a sterile dressing to maintain an airtight seal.
The Drainage System Mechanism
The chest tube connects to a closed drainage system that operates on a series of chambers below the patient’s chest. The first component is the collection chamber, a calibrated compartment that receives and measures the air and fluid draining from the patient.
Following this is the water seal chamber, which contains sterile water and functions as a one-way valve. The submerged tube tip creates a seal, allowing air and fluid to exit the chest while preventing re-entry. This seal maintains the necessary negative pressure within the chest.
The third component is the suction control chamber, which regulates the negative pressure applied to the system. This chamber is often connected to an external suction source. In a wet suction system, the water level determines the maximum negative pressure, commonly set at -20 cm of water.
Monitoring and Removal
Continuous monitoring is necessary to ensure the chest tube is functioning correctly. A key observation is tidaling, the fluctuation of the water level in the water seal chamber with the patient’s breathing. Tidaling demonstrates that the tube remains patent and is influenced by the pressure changes in the chest cavity.
Bubbling in the water seal chamber indicates air is actively escaping from the chest, often signifying an air leak from the lung. While expected with a pneumothorax, continuous, excessive bubbling may point to a leak within the drainage system itself. The tube remains in place until the drainage volume is minimal, typically less than 200 to 300 milliliters over a 24-hour period, and no air leak is observed.
Once the lung is fully re-expanded and the drainage criteria are met, the chest tube can be removed rapidly. The patient is asked to exhale deeply to minimize the chance of air re-entering the pleural space. After the tube is withdrawn, the insertion site is immediately covered with an occlusive dressing to seal the wound and prevent a recurrent pneumothorax.