Water Seal Chest Tube System
A water seal chest tube is a drainage system that allows unidirectional flow of air or fluid out of the pleural space while preventing atmospheric air from entering the chest cavity. 1 This system is essential for treating conditions such as pneumothorax, hemothorax, pleural effusion, and post-surgical drainage.
Components and Function
The water seal chest tube system consists of:
- Chest tube: Inserted into the pleural space (typically 16F-22F for most patients, 24F-28F for large air leaks or bronchopleural fistulas) 1
- Collection chamber: Collects drained fluid
- Water seal chamber: Contains water with a tube submerged 1-2 cm deep 1
- Suction control chamber: Optional component for applying controlled negative pressure
How the Water Seal Works
The water seal functions as a one-way valve:
- Air can exit from the pleural space through the tube and bubble through the water
- The water prevents atmospheric air from flowing back into the pleural space
- Respiratory swing (fluctuation of fluid level with breathing) indicates tube patency 1
Clinical Applications
For Pneumothorax Management:
- Recommended as first-line drainage system for pneumothorax management with good consensus 1
- Initially used without suction, but suction should be applied if the lung fails to re-expand 1, 2
- Allows monitoring of air leaks - bubbling indicates continued air leak from the lung 1
For Pleural Effusion/Hemothorax:
- Enables controlled drainage of fluid
- Initial drainage should be limited to 10 ml/kg to prevent re-expansion pulmonary edema 1
- The drain should be clamped for 1 hour after initial drainage of this volume 1
Critical Safety Considerations
- The underwater seal bottle must always be kept below the level of the patient's chest to prevent backflow 1
- A bubbling chest drain should never be clamped as this can lead to tension pneumothorax 1, 2
- If a drain is clamped (e.g., during fibrinolytic therapy), it must be immediately unclamped if the patient develops breathlessness or chest pain 1
- Chest tubes should be removed in a staged manner after confirming resolution of pneumothorax and absence of air leak 1
Advantages and Disadvantages
Advantages:
- Provides visual confirmation of air leak and drainage
- Allows assessment of tube patency through respiratory swing
- Can be connected to suction if needed
Disadvantages:
- Requires inpatient management
- Limits patient mobility
- Risk of knocking over the collection system 1
- Requires careful positioning below patient's chest level at all times 1
Modern Alternatives
While the traditional water seal system remains standard, alternatives include:
- Electronic drainage systems that provide digital measurement of air leak 3
- Heimlich valve systems for ambulatory management of select patients 1
The water seal chest tube system remains a cornerstone of pleural space management, providing effective drainage while preventing complications such as tension pneumothorax through its simple but ingenious design.