Chest Tube 101

Respiratory mechanics

The thoracic cavity is limited by the chest wall and diaphragm. Thin, wet pleural membranes cover the thoracic cavity while the lungs are covered by visceral pleura. Normally, the two pleurae are flush against each other and the intrapleural space is only a potential space.

The intrapleural pressure (approximately -5cm H2O at rest) is always less than the intrapulmonary and atmospheric pressures; this is what prevents the lungs from collapse at any given time.

 During inspiration: chest wall and diaphragm expand, intrapleural space becomes a greater negative pressure (-10cm H2O), and intrapulmonary pressure becomes subatmospheric in order to pull air into the airways and alveoli.

During expiration: the chest wall and diaphragm return to baseline, the intrapleural pressure returns to baseline (-5cm H2O), the intrapulmonary pressure becomes greater than the atmospheric pressure in order to push air out.

When air, fluid, or blood accumulates in the potential pleural space, it causes the lung to partially or fully collapse and impedes on the normal respiratory mechanics. This requires chest tube placement and drainage.

Early drainage system

Up-to-date version

Water seal chamber

Fill water seal chamber to 2cm fill line (with ~45ml of sterile water that comes with drainage unit.) The depth (2cm) determines the hydrostatic pressure that needs to be overcome during expiration. Markings (1-5) allow graduated air leak monitoring (to objectively track improvement.)

Suction control

The suction regulator is preset at -20cm H2O. However, you must set wall suction to (at least) -80mmHg in order for the pleural space to experience -20cm H2O. Bellows will expand to or beyond the ∆ when suction is operating at -20cm H2O or higher.

When on suction: patient’s pleural pressure will equal suction control setting PLUS height of water in water seal column.

Tidaling

Tidaling is the fluctuating water level in the water seal column; it elevates with inspiration and returns to baseline (2cm) with expiration. No tidaling means either A) blockage in tubing (clot, kinking) or B) lungs have re-expanded.

Air leak

Continuous bubbling or bubbling with deep cough (seen in water seal chamber) means air is leaking into the pleural cavity from either A) around incision/insertion site of chest tube or B) tear in pulmonary pleura. Markings (1-5) allow graduated air leak monitoring (to objectively track improvement.)

Shannon Zielsdorf MD

General surgery PGY1

Rush University / JHS Cook County Hospitals