A chest tube is a flexible, hollow tube inserted into the pleural space (the area between the lungs and the chest wall). Its primary function is to remove unwanted accumulations of air, fluid, or blood. When these substances build up, they create pressure that prevents the lung from fully expanding, leading to conditions like pneumothorax or pleural effusion. External mechanical assistance, known as wall suction, is often used to facilitate this drainage process and promote rapid lung re-expansion. This mechanism creates a controlled negative pressure gradient to steadily pull contents from the chest cavity.
Understanding the Drainage System Components
Modern chest drainage systems are engineered units that manage the output from the chest tube while safely maintaining the necessary negative pressure. These systems typically incorporate three functional chambers. The collection chamber is a calibrated reservoir that receives and measures the volume of fluid or blood draining from the patient’s chest. This allows healthcare providers to accurately track the drainage rate and total output over time.
The second chamber is the water seal, which acts as a one-way valve, allowing air and fluid to exit the chest but preventing atmospheric air from re-entering the pleural space. This seal requires sterile water, often 2 centimeters, to function correctly. Maintaining a closed system is important to prevent tension pneumothorax, a complication where air accumulates rapidly in the pleural space.
The third component is the suction control chamber, which regulates the amount of negative pressure applied to the system by the external wall suction source. Suction control can be managed through a water-based system (using a column of water) or a dry suction system (using a self-regulating valve and a dial). The suction control chamber is the physical interface where the controlled negative pressure from the wall unit is introduced.
Preparing the Patient and Equipment
Before connecting the drainage system, several preparatory steps must be completed. Equipment gathering involves collecting the sterile chest drainage unit, appropriate tubing, a wall suction regulator, and sterile water or saline. Check the expiration date and integrity of the sterile components before opening the packaging.
The patient should be positioned in a semi-Fowler’s position (30 to 45-degree angle), unless medically contraindicated. This position promotes comfort and facilitates maximum drainage by gravity.
Next, the drainage unit itself must be prepared according to the manufacturer’s instructions. If using a wet suction system, sterile water must be added to the water seal chamber, usually up to the 2 cm mark, to establish the barrier. If the unit uses a water column for suction control, sterile water is added to that chamber to the predetermined level, often corresponding to negative 20 centimeters of water pressure (-20 cm H2O). This preparation ensures the system is ready to receive the tube connection and the external suction source.
Step-by-Step Connection to Wall Suction
The process of connecting the chest tube to the wall suction begins by securing the patient’s chest tube to the inlet port of the drainage unit with a firm, twist-locking motion. This connection must be tight and sealed to prevent air leaks that would compromise the negative pressure within the system. Once connected, the entire unit should be placed upright below the level of the patient’s chest to promote drainage via gravity.
Attention shifts to the suction control mechanism on the drainage unit itself. For most applications, the drainage unit is internally set to a standard negative pressure, typically negative 20 centimeters of water (-20 cm H2O). On a dry suction system, this setting is achieved by rotating a dial until the indicator displays the desired pressure level. This dial limits the maximum suction applied to the patient’s chest, regardless of the wall suction setting.
For a water-based system, the negative 20 cm H2O setting is established by the height of the water column in the suction control chamber. After setting the internal limit, connect the dedicated suction tubing from the drainage unit’s suction port to the wall suction regulator. This regulator is the interface between the unit and the hospital’s vacuum source, which provides the power for the suction.
The wall suction regulator must be activated and then adjusted to generate the required vacuum. The wall regulator’s dial does not determine the pressure applied to the patient; instead, it determines the vacuum needed to activate the unit’s internal regulator. The wall vacuum must be set high enough to overcome the resistance of the drainage system and activate the unit’s internal pressure control.
In a water-based suction system, the wall regulator is turned up until a gentle, continuous bubbling is observed in the water column of the suction control chamber. This gentle bubbling confirms that the wall vacuum is sufficient to maintain the set negative pressure. Excessive, vigorous bubbling is unnecessary and causes rapid water evaporation and distracting noise.
With a dry suction system, the wall regulator is adjusted until a float ball, bellows, or indicator window on the unit enters the “set” or “active” range. This visual confirmation indicates that the wall vacuum is successfully engaging the unit’s internal pressure-regulating valve. The adjusted wall pressure is often 80 to 120 millimeters of mercury (mmHg), but the pressure transmitted to the patient remains the lower, controlled setting of the drainage unit.
Verification and Initial Patient Monitoring
Once the system is fully connected and the wall suction is activated, immediate verification of the system’s function is required. The water seal chamber must be observed for “tidaling,” which is the normal fluctuation of the water level corresponding with the patient’s respiratory cycle. The water level rises during inspiration and falls during expiration, reflecting changes in intrapleural pressure. The absence of tidaling suggests either the lung is fully re-expanded or the tubing is kinked or blocked, requiring further assessment.
Observation of the water seal chamber for continuous or intermittent bubbling indicates an air leak. Intermittent bubbling corresponding with coughing or expiration suggests air is still leaking from the lung, which is expected with a resolving pneumothorax. Continuous bubbling that persists throughout the respiratory cycle suggests a persistent leak, such as a loose connection, requiring immediate investigation.
The appropriate level of suction activity must be confirmed by checking the suction control chamber, either via gentle bubbling in a wet system or the indicator status in a dry one. After confirming system integrity, focus shifts to the patient. A rapid assessment of vital signs, respiratory rate, and effort establishes a new baseline after the procedure. Any sudden changes in oxygen saturation, increased difficulty breathing, or severe chest pain warrant immediate intervention and re-evaluation of the entire setup.