A chest tube drainage system is a medical device designed to restore the normal functioning of the lungs by re-establishing negative pressure within the chest cavity. This system connects a tube inserted into the patient’s chest to a closed unit that manages the removal of unwanted air, fluid, or blood. The dry suction chest tube system is a modern advancement that replaces older water-based mechanisms for controlling vacuum pressure. This system uses a mechanical regulator to achieve precise, controlled suction without the need for constant water level monitoring. Understanding the components and mechanics of the dry suction model reveals how this device supports lung re-expansion and drainage.
Why Pleural Drainage is Necessary
The lungs are encased by two thin layers of tissue called the pleura, which form the pleural space. This space normally contains only a small amount of lubricating fluid and maintains a pressure that is slightly negative relative to the atmosphere. This negative pressure keeps the lungs fully expanded against the chest wall, allowing efficient breathing mechanics.
When the integrity of the chest wall or the lung surface is compromised, air or excess fluid can enter the pleural space, disrupting this negative pressure balance. The accumulation of air (pneumothorax) or blood and fluid (hemothorax or pleural effusion) compresses the lung, leading to partial or complete collapse. Pleural drainage is the procedure of inserting a chest tube to remove this unwanted material.
Immediate drainage is necessary to relieve pressure on the lung and heart, restoring the negative pressure gradient required for proper lung inflation. Without this intervention, the lung cannot fully expand, severely hindering oxygen exchange and potentially leading to respiratory distress. The chest drainage system serves as the controlled pathway for removal and prevents outside atmosphere from re-entering the chest cavity.
The Basic Components of a Chest Drainage System
A modern disposable chest drainage system integrates three distinct functional areas: the collection chamber, the water seal chamber, and the suction control chamber. The patient’s chest tube connects directly to the collection chamber, which is the first stop for any material draining from the pleural space. This chamber is calibrated to allow healthcare providers to accurately measure the volume and assess the type of output over time.
The water seal chamber follows the collection chamber and acts as a one-way valve, a design feature common to both wet and dry systems. This chamber is filled with a small amount of water, typically to the 2 cm mark, which creates a seal. Air or fluid leaving the patient can bubble out through the water, but the water column prevents atmospheric air from being drawn back into the chest during inhalation.
The water in the seal chamber also reflects the pressure changes within the pleural space, a phenomenon known as “tidaling.” As the patient inhales, the water level rises because the intrapleural pressure becomes more negative, and it falls during exhalation. The suction control chamber is the final compartment, where the external vacuum source connects and the prescribed level of negative pressure is regulated.
How Dry Suction Regulates Pressure
The dry suction system distinguishes itself by using a mechanical regulator to control the negative pressure applied to the patient, rather than relying on a water column. This regulator is a dial on the side of the unit that allows the user to set the desired level of suction, often standardized at -20 cm of water pressure (-20 cmH2O) for adults, though it can be adjusted from -10 to -40 cmH2O.
The internal mechanism uses a spring-loaded valve or a diaphragm to maintain the set pressure. When connected to a suction source, the mechanical regulator automatically adjusts the airflow to ensure the pressure reaching the patient does not exceed the dial setting. Fluctuations in the external vacuum source intensity do not affect the pressure applied to the chest.
A visual indicator, often an orange bellows or a float ball, confirms that the system is actively regulating the pressure. The bellows expands fully into a marked window when the wall suction provides enough flow to activate the internal mechanism. This mechanical control makes the dry system quieter and allows for a faster setup since no water is required in the suction control chamber.
Practical Assessment and Monitoring
Monitoring the dry suction chest drainage system involves observing specific visual cues across the chambers to confirm proper function and patient status. Tidaling in the water seal chamber is an expected sign, indicating the chest tube remains open and connected to the patient’s breathing pressure changes. If tidaling ceases, it may suggest the lung has fully re-expanded, or that the tubing is kinked or blocked.
A dry suction system should be silent; continuous bubbling in the water seal chamber is a sign of an air leak. Intermittent bubbling suggests an air leak from the patient’s lung that is still healing. Persistent, vigorous bubbling indicates an ongoing leak either from the patient or within the drainage system itself. The visual indicator, such as the expanded bellows, must be checked regularly to confirm the external suction source is adequate to maintain the set negative pressure.
The collection chamber requires frequent assessment to monitor the volume and character of the drainage. Output measurements are marked on the chamber at regular intervals to track the rate of fluid removal. Changes in the amount or appearance of the drainage, such as a sudden increase or a change in color, provide important information about the patient’s condition and the ongoing need for drainage.