Principles of Pleural Drainage
The lungs reside within the chest cavity, surrounded by a double-layered membrane known as the pleura. A small amount of lubricating fluid normally exists between these two pleural layers, allowing the lungs to expand and contract smoothly during breathing. The space between these layers, called the pleural space, maintains a negative pressure relative to the atmosphere, which acts like a vacuum, keeping the lungs fully inflated and against the chest wall. This negative pressure is essential for effective respiration, as it helps draw air into the lungs when the diaphragm contracts.
When this delicate balance is disrupted, the negative pressure within the pleural space can be lost. Conditions such as a pneumothorax, where air enters the pleural space, or a hemothorax, where blood accumulates, can compromise the lung’s ability to expand. Similarly, an excessive buildup of fluid, known as a pleural effusion, can compress the lung, hindering its function. In these situations, the lung may partially or completely collapse, leading to significant respiratory distress and impaired oxygen exchange.
The fundamental principle of pleural drainage involves re-establishing this negative intrapleural pressure by removing unwanted air, fluid, or blood from the pleural space. A chest tube provides a conduit for these substances to exit the body, allowing the collapsed or compressed lung to re-expand. This process restores the physiological conditions necessary for the lung to resume its normal role in gas exchange, thereby alleviating the patient’s breathing difficulties.
Indications for Chest Tube Placement
Its purpose is to restore normal lung function by removing these unwanted substances. This procedure is performed for various medical conditions that compromise the integrity of the pleural space and subsequently, lung function.
One common indication is pneumothorax, a condition where air accumulates in the pleural space, causing the lung to collapse. This can occur spontaneously, due to trauma, or as a complication of medical procedures. Another significant reason for chest tube insertion is hemothorax, blood in the pleural space, often resulting from trauma.
Malignant pleural effusion, fluid buildup due to cancer, often necessitates chest tube placement. Empyema, pus in the pleural space, requires drainage to treat infection. Chylothorax, lymphatic fluid leakage, also requires drainage. Chest tubes are also used post-operatively following thoracic surgeries to drain residual air and fluid.
Components and Function of the Water Seal System
A standard chest drainage unit (CDU) has three chambers. The collection chamber connects to the patient’s chest tube. This chamber is calibrated with volume markings, allowing healthcare providers to accurately measure the amount of fluid, blood, or pus draining from the pleural space over time. Observing drainage volume, color, and consistency provides important patient information.
Adjacent to the collection chamber is the water seal chamber, which functions as a one-way valve. It contains sterile water, typically filled to a 2 cm level, through which air from the pleural space bubbles. The water barrier allows air to escape from the patient’s chest into the atmosphere, but prevents atmospheric air from re-entering the pleural space.
Tidaling, the fluctuation of the water level with respiration, is a key observation. During inhalation, the water level rises as intrapleural pressure becomes more negative, and during exhalation, it falls. Tidaling indicates tube patency and connection to the pleural space, showing the lung has not fully re-expanded. Bubbling in the water seal chamber signifies the presence of an air leak from the pleural space; continuous bubbling suggests an ongoing air leak, while intermittent bubbling indicates a resolving air leak or air escaping with exhalation.
The third chamber is the suction control chamber, which regulates negative pressure. This chamber can be a wet system (where the depth of a water column determines the suction level) or a dry system (which uses a dial to set the desired suction pressure). Controlled suction enhances air and fluid removal, promoting lung re-expansion. The suction level is prescribed by a physician.
Connecting a Chest Tube to the Water Seal System
Once a chest tube has been safely inserted into the patient’s pleural space, the next critical step involves securely connecting it to a water seal drainage system. Before initiating the connection, it is important to gather all necessary equipment, including a new, sterile chest drainage unit, sterile water or saline for the water seal and suction chambers, and appropriate connecting tubing. Preparing the drainage unit involves filling the water seal chamber with sterile water to the designated level, typically 2 cm, and filling the suction control chamber if it is a wet system, also to the prescribed level.
Maintaining strict sterile technique throughout the connection process is paramount to prevent the introduction of infection into the patient’s pleural space. This involves using sterile gloves and ensuring that all connection points remain aseptic. The patient’s chest tube, which is typically clamped during insertion and initial setup, is then carefully attached to the inlet port of the drainage unit’s collection chamber. This connection should be firm and secure to prevent dislodgement or air leaks.
After the primary connection is made, it is often necessary to secure the tubing connections with tape or specialized locking mechanisms to prevent accidental disconnection. The drainage unit must then be positioned upright and placed below the level of the patient’s chest. This gravity-dependent positioning is essential for effective drainage and prevents fluid from flowing back into the pleural space.
Upon connection, initial checks are performed to ensure the system is functional. Observing for tidaling in the water seal chamber confirms patency and connection to the pleural space. Any initial bubbling in the water seal chamber indicates the immediate evacuation of air from the pleural space. If suction has been ordered, it is then connected to the suction control port of the drainage unit and set to the prescribed level, ensuring the suction device is functioning correctly and consistently.
Patient Care and Troubleshooting with a Chest Tube
Ongoing assessment of the patient’s respiratory status is a continuous priority when a chest tube is in place. Regular monitoring of breathing patterns, respiratory rate, oxygen saturation, and lung sounds helps to identify improvements or any signs of respiratory distress promptly. Any changes in the patient’s condition, such as increased shortness of breath or decreased oxygen levels, warrant immediate investigation.
Monitoring the drainage from the chest tube is also an ongoing process. The volume, color, and consistency of the fluid in the collection chamber should be assessed at regular intervals, typically hourly initially and then less frequently as drainage subsides. A sudden increase in drainage volume or a change from serous to bloody drainage could indicate a new complication, while a decrease might signify resolving issues or a potential obstruction.
Observing the water seal chamber for tidaling and air leaks provides dynamic information about the pleural space. The presence of tidaling confirms the tube’s patency and lung movement, while its absence may suggest lung re-expansion, tube obstruction, or a disconnected system. Intermittent bubbling, often seen with coughing or exhalation, indicates air escaping from the pleural space, while continuous bubbling suggests a persistent air leak or a leak within the drainage system itself.
Ensuring the chest tube remains patent is crucial for effective drainage. The tubing should be free of kinks, loops, or clots that could impede flow. Troubleshooting common issues involves addressing these potential obstructions; for example, if there is no tidaling and the patient’s respiratory status is unchanged, checking for kinks in the tubing is a primary step. Excessive continuous bubbling might necessitate checking all connections for tightness, while a sudden increase in drainage could point to a new bleed. Signs such as subcutaneous emphysema, characterized by air under the skin around the insertion site, or dislodgement of the tube, require immediate medical attention.