From the Guidelines
A water seal is a crucial component in chest drainage systems, acting as a one-way valve to prevent air from entering the pleural space while allowing air and fluid to escape, and its use is supported by recent guidelines such as the British Thoracic Society guideline for pleural disease 1.
Key Components of a Water Seal
- A collection chamber for fluid from the chest
- A water seal chamber with sterile water, typically 2 cm deep
- Sometimes, a suction control chamber
Functionality
The water seal prevents atmospheric air from entering the pleural space, allowing air and fluid from the chest to escape. This is achieved because air bubbles can pass through water in one direction, but the water creates a barrier preventing backflow.
Clinical Indications
Water seals are commonly used in treating pneumothorax (collapsed lung) and following thoracic surgeries. The bubbling in the water seal chamber indicates air is being removed from the pleural space, while cessation of bubbling typically suggests the lung has re-expanded.
Importance in Clinical Practice
Water seals are vital for maintaining negative pressure in the pleural space, which helps re-expand the lung and restore normal respiratory function, as emphasized in guidelines for managing pleural infections and pneumothorax 1.
Practical Considerations
It is essential to keep the water seal device below the level of the patient’s chest at all times and to monitor for signs of air leak or blockage, such as continuous bubbling or lack of respiratory swing in the fluid in the chest tube 1.
Recommendation
The use of a water seal in chest drainage systems is recommended for its effectiveness in preventing air entry into the pleural space and facilitating lung re-expansion, as supported by the most recent and highest quality evidence 1.
From the Research
Definition of Water Seal
- Water seal is a method of chest drainage where the chest tube is connected to a water seal chamber, allowing air to escape but preventing air from entering the chest cavity 2.
- The water seal chamber acts as a one-way valve, allowing air to bubble out of the chamber as the patient exhales, but preventing air from entering the chamber as the patient inhales.
Comparison with Suction
- Studies have compared the effectiveness of water seal versus suction in managing air leaks after pulmonary surgery 2, 3, 4, 5, 6.
- The results suggest that water seal may be superior to suction in stopping air leaks, but suction may be beneficial in reducing the occurrence of postoperative pneumothorax 2, 3, 5.
- However, other studies have found no significant difference between water seal and suction in terms of air leak duration, length of hospital stay, or incidence of prolonged air leak 4, 6.
Indications and Contraindications
- Water seal may be indicated for patients with small to moderate air leaks, as it allows for the gradual resolution of the air leak without the need for suction 2.
- However, water seal may not be suitable for patients with large air leaks or those at risk of developing pneumothorax, as it may not provide sufficient drainage 2, 3, 5.
- Suction may be preferred in these cases, as it can provide more effective drainage and reduce the risk of pneumothorax 3, 5.
Clinical Implications
- The choice between water seal and suction should be based on individual patient factors, such as the size and location of the air leak, and the patient's overall clinical condition 2, 3, 4, 5, 6.
- Clinicians should carefully monitor patients with air leaks and adjust their management strategy as needed to minimize complications and optimize outcomes 2, 3, 4, 5, 6.