A chest tube is a flexible, hollow device used to restore normal lung function. Its purpose is to drain air, fluid, or blood collected in the pleural space surrounding the lungs. Since this collection can cause the lung to collapse, the chest tube removes the excess volume, allowing the lung to fully re-expand and restoring necessary negative pressure. This process uses a carefully monitored closed drainage system.
The Mechanics of Chest Drainage Systems
The chest tube connects to a closed drainage system, typically a disposable unit with three main chambers. The first is the collection chamber, where fluid draining from the chest (such as blood or pleural fluid) is gathered and measured. This chamber is calibrated, allowing staff to track the amount of drainage over time.
The second section is the water seal chamber, which acts as a one-way valve. It allows air and fluid to exit the chest cavity while preventing atmospheric air from re-entering. This is achieved by submerging the tip of a tube in sterile water. The third component is the suction control chamber, used if constant negative pressure is needed to help pull air or fluid out of the chest.
Understanding Expected Bubbling in the Water Seal
Bubbling in the water seal chamber is the direct result of air escaping from the patient’s chest and passing through the water barrier. When a patient has a pneumothorax, intermittent or sporadic bubbling is considered a normal finding. This bubbling often correlates with changes in intrathoracic pressure, meaning it may increase when the patient coughs or exhales forcefully.
The movement of the water level, known as tidaling, is an expected observation that confirms the system is patent. Tidaling reflects changes in pressure within the chest. With each breath, the water level rises slightly with inhalation and falls with exhalation. This movement indicates the drainage system is working and the lung has not yet fully re-expanded. If the patient is on a mechanical ventilator, the direction of this fluctuation may be reversed.
When Bubbling Indicates a Concern
While intermittent bubbling is normal, vigorous, continuous bubbling suggests a significant air leak requiring immediate attention. This may indicate a large air leak from the patient’s lung that has suddenly worsened. More often, continuous bubbling signals an external leak within the drainage system, such as a loose connection.
A sudden, complete cessation of bubbling and tidaling is a cause for concern if the lung is not yet fully healed. This lack of movement may signal a kink in the tubing, a clot blockage, or tube compression. These issues prevent the removal of air or fluid, which could lead to a dangerous buildup of pressure in the chest. The tubing should be checked immediately for obstructions, and medical staff must be notified.
Signs of Lung Healing and Tube Removal Readiness
As the patient’s lung heals and begins to fully re-expand, the air leak into the pleural space gradually stops. This progression is visible in the water seal chamber as intermittent bubbling slows down and eventually ceases completely. The absence of bubbling indicates that air is no longer escaping from the lung tissue.
Tidaling, or fluctuation of the water level, will also disappear once the lung has fully re-expanded and sealed against the chest wall. The disappearance of both bubbling and tidaling indicates the chest tube has served its purpose and may be ready for removal. The medical team confirms this resolution with a chest X-ray to ensure the lung is fully inflated before removal.