Define tidaling and explain what a normal tidaling pattern indicates.

• A. Tidaling is water level rising with gravity drainage.
• B. Tidaling is the fluctuation of the water level in the water-seal chamber with respiration; normal tidaling indicates an open pleural space and a patent system.
• C. Tidaling refers to color changes in drainage.
• D. Tidaling is the water level remaining completely still.

Answer: (B)

Tidaling is the fluctuation of the water level in the water-seal chamber that mirrors the patient’s breathing. As you breathe in, intrapleural pressure becomes more negative, pulling air from the pleural space through the chest tube into the water seal and causing the water level to rise; as you breathe out, the pressure becomes less negative and air is pushed back toward the pleural space, causing the water level to fall. A normal tidaling pattern means this rise and fall occur with respiration, indicating the pleural space is open and the chest drainage system is patent. This shows the lung and pleural space are communicating with the drainage system and that air or fluid can move as the patient breathes. If tidaling stops, or is absent, it can signal a blocked tube or a fully expanded lung; if tidaling is continuous or exaggerated, it may indicate an ongoing air leak.