Pleural Drainage Systems

Most commercially available pleural drainage systems use the three bottle model of closed drainage and suction. The most important bottle, the underwater seal, serves as a one-way valve that allows air and fluid to leave the pleural cavity without the risk of re-entry during inspiration. Bubbling in this bottle indicates an on-going air leak, either from the patient or from the system itself. The other two bottles typically contained in drainage systems are: the collection bottle, which is connected directly to the patient for accumulation of pleural fluid and/or debris, and a suction system that connects to wall suction but regulates the amount of suction actually delivered to the pleural space via a column of sterile water. The pleural drainage system must be kept approximately 40 inches (100cm) below the level of the patient in order to prevent retrograde flow of air or fluid back into the pleural space.


  1. Firmly connect the free end of the chest tube to the sterile drainage system and secure with tape to prevent accidental disconnection
  2. Unclamp the free end of the chest tube
  3. If pleural fluid is being drained, the fluid level in the drainage system will rise
  4. If a pneumothorax is being evacuated, air bubbles will appear in the underwater seal bottle. DO NOT re-clamp the chest tube while there is bubbling as this may lead to recollection of a pneumothorax and may induce a tension pneumothorax
  5. Suction may be applied if there is a persistent pneumothorax despite the underwater seal or if a viscous pleural collection is not draining effectively. Usually the suction level is set to 20cmH20 at the Pleurevac
  6. To avoid re-expansion pulmonary edema when evacuating chronic large pulmonary effusions, avoid collection of 1.5 L or more within a 30 minute period