A chest tube is a flexible, hollow device inserted into the pleural space—the area between the lung and the chest wall—to remove unwanted air, fluid, or blood. This procedure is necessary when conditions like a pneumothorax or a hemothorax disrupt the natural negative pressure required for lung expansion. Connecting the chest tube to a closed chest drainage system and then to wall suction maintains therapeutic negative pressure and ensures patient safety. Proper preparation of the drainage unit and verification of the suction mechanism are fundamental steps.
Preparing the Chest Drainage Unit
The first step in setting up a chest tube system is the preparation of the disposable chest drainage unit, completed before connecting to the patient. This unit collects drainage, acts as a one-way valve, and controls the level of suction applied. Preparation involves adding sterile fluid to the chambers that regulate the system’s function, primarily the water seal and the suction control chamber.
The Water Seal Chamber acts as a safety barrier, preventing air or fluid from being drawn back into the patient’s chest; it functions as a one-way valve. This chamber must be filled with sterile water or saline, typically to the 2-centimeter mark indicated on the unit. This fluid column allows air to escape from the pleural space but prevents atmospheric air from re-entering the system, preserving the necessary negative pressure.
A key difference in preparation lies between wet and dry suction systems, both designed to apply a consistent negative pressure, often -20 cm of water pressure. For a traditional wet suction unit, the Suction Control Chamber must be filled with sterile water precisely to the prescribed negative pressure level, such as the -20 cm H2O line. The depth of the water column determines the actual amount of suction delivered to the patient, regardless of the wall suction strength.
In contrast, a dry suction system simplifies setup by eliminating the need to fill the suction control chamber with fluid. The desired negative pressure, typically ranging from -10 to -40 cm H2O, is set by turning a dial directly on the drainage unit. This mechanical regulator controls the suction pressure applied to the patient, offering a faster setup and the benefit of being less susceptible to changes from water evaporation.
Connecting the Unit to the Patient and Wall Suction
Once the drainage unit is prepared, the next phase involves securely connecting the system to both the patient and the external vacuum source. Maintaining sterile technique is paramount to prevent the introduction of pathogens into the patient’s pleural space. The sterile tubing extending from the chest drainage unit must be connected directly to the chest tube inserted into the patient.
The connection point must be secured immediately to prevent accidental separation, which would compromise the closed system and expose the pleural space to atmospheric pressure. Health professionals often use specific connecting devices or apply tape in a secure, non-circular manner to ensure the junction remains airtight and stable. The tubing should hang straight down from the patient to the drainage unit, avoiding kinks or dependent loops that could impede the flow of fluid or air.
The final connection is made between the drainage unit’s suction port and the wall suction regulator using connecting tubing. This external vacuum source provides the power for the suction mechanism but does not control the pressure delivered to the patient. To ensure the drainage unit’s internal regulator functions correctly, the wall suction regulator must be set to a level significantly higher than the pressure prescribed for the patient.
For a patient prescribed -20 cm H2O, the wall regulator is typically set to a high level, often between -80 and -120 mmHg. This high external setting guarantees that the unit’s internal mechanism (the water column or the dial) has sufficient vacuum to precisely regulate and maintain the ordered negative pressure within the chest cavity. The high wall setting is merely the vacuum source; the drainage unit remains the true controller of the therapeutic suction level.
Activating and Verifying Suction Function
After all connections are secured, the wall suction source is activated to begin drainage. The immediate priority is to verify that the system is functioning correctly and applying the intended negative pressure. This verification process differs depending on whether a wet or dry suction system is in use.
In a wet suction system, the correct application of wall suction is confirmed by observing the suction control chamber for gentle, continuous bubbling. This bubbling occurs as the wall suction pulls air through the water column, confirming the external vacuum is sufficient to overcome the water-level resistance. Vigorous or turbulent bubbling is inefficient, causing excessive water evaporation and unnecessary noise. If this occurs, the wall suction is set too high and requires reduction at the wall regulator until the bubbling is gentle.
For a dry suction system, verification is achieved by observing a specific visual indicator, such as an orange bellows or a float, which expands or appears in a designated window. The full expansion of this indicator confirms that the wall suction is providing enough vacuum for the internal regulator to maintain the dialed-in negative pressure. If the indicator is not fully expanded, the wall suction pressure must be increased until visual confirmation is achieved.
The Water Seal Chamber must be immediately assessed for two distinct signs: tidaling and air leaks. Tidaling is the normal fluctuation of the water level corresponding with the patient’s breathing, confirming the system is patent and connected to intrapleural pressure changes. Continuous, vigorous bubbling in the water seal chamber signals a persistent air leak, requiring a systematic check of all connections and the chest tube insertion site to locate the source. Finally, the initial amount, color, and consistency of the fluid draining into the collection chamber must be documented to establish a baseline.