Although small amounts of air and fluid in the pleural space are generally well tolerated, pneumothorax, hemothorax, chylothorax, etc. necessitates chest tube placement. For large air collections, smaller bore tubes can often be utilized and placed more apically as air rises. Viscous fluid collections (complicated effusions, hemothorax, empyema, etc.) often require large bore tubes in the dependent lung base(s) since gravity pulls fluid to these regions.
After a chest tube is placed, it’s connected to a drainage system like an Atrium (which I’ll be referencing in this post). This closed system consists of three chambers: collection, water-seal, and suction control.
This chamber collects and measures output which can be marked at regular time intervals. The characteristics of the output can also be visually assessed (ie, milky chylothorax after initiation of nutrition may suggest thoracic duct injury). Remember that a drop of blood in a bucket of water will tint the entire thing red, so not all “red drainage” is considered “sanguineous.” Always ensure an airtight seal between tubing interfaces with adapters, tape, and zip ties.
Remember that during a normal, spontaneous inspiratory breath, the diaphragm contracts downward increasing intrathoracic volume while simultaneously creating a “negative pressure” relative to the outside world. Airflow is directed into the lungs from the environment down a pressure gradient. What’s to say that air can’t be pulled back into the chest via a tube sitting in the pleural space? The water-seal!
The water-seal chamber serves as a one-way valve – air can escape from the pleural space but cannot reenter. This is accomplished by maintaining a column of sterile water at 2 cm in the Oasis systems. Remember that normal tidaling (water level rises with inspiration and falls with expiration if spontaneously ventilating, opposite if receiving positive pressure ventilation) means that this chamber can “see” the pleural space pressure changes suggesting the chest tube is indeed patent. Vigorous, constant bubbling in this chamber suggests a persistent air leak (bronchopleural fistula, persistent pneumothorax, etc.)
SUCTION CONTROL CHAMBER
Suction is applied via the suction port, and on drainage systems like the Atrium, suction strength can be directly toggled (typically -20 cm H2O ). Bellows will also expand confirming the integrity of the suction system.
When we “water seal” a patient, suction is removed and drainage is monitored to gravity along with signs of air reaccumulation (repeat chest x-ray in a few hours, symptoms of dyspnea, etc.) Depending on the physician’s preference and clinical circumstances, this is often a good test prior to removing the chest tube.
Here are things I look for as an intensivist when examining patients with chest tubes connected to Atrium drainage systems.
- How does the site look? Is it oozing? Does another stitch need to be placed? Does the dressing need to be changed or reinforced? Are the tube’s outermost drainage holes still within the pleural space on chest x-ray? Is there a chance that the drain is not well situated WITHIN the fluid collection?
- Let’s follow the tube to the drain: are there any clamps, large clots, tube kinks, etc. that will limit drainage? Although I’ve seen countless colleagues “milk” chest tubes to remove debris, there really hasn’t been any evidence supporting this practice. In fact, one can create negative pressure within the tube transmitted back to the pleural space.
- Is the Atrium BELOW the site of drainage? Remember, gravity is your friend! Is it stabilized against something like a bed frame or IV pole?
- Is the water seal chamber appropriately filled to 2 cm? Remember, less water = less suction pressure. Do I see tidaling or a persistent air leak?
- Is the suction tubing connected (or not connected) appropriately? For safety, in post-pneumonectomy patients, I make sure the suction port is broken off or taped over. Inadvertently applying suction can result in significant mediastinal shift with possible cardiopulmonary consequences.
- Are there clamps available nearby?
Now let’s talk about accidents/emergencies surrounding chest tubes:
- If the tube is disconnected from the drainage system, immediately clamp it! Depending on hospital policy, the entire chest tube may need to be replaced or the ends of the tube and drainage system sterilized prior to reconnection. This is why I’m paranoid about properly securing tubes to the drainage systems with zip ties!
- If the tube falls out entirely from the chest, immediately apply an occlusive dressing like Xeroform gauze at end expiration. If this is done after inspiration, air entrained in the pleural space through the chest wall defect may now become trapped (pneumothorax).
- Acute increase in bright red blood suggests an active bleed. In the immediate post-operative period, this can sometimes be managed by fixing coagulopathy but often time requires re-exploration of the chest.
As far as clamping the chest tube, if I see an air leak that just doesn’t make sense, sometimes I’ll briefly clamp the tube at the exit point of the chest. If the leak persists, the leak is somewhere in the system itself. Chest tubes are also briefly clamped as the drainage system is changed.
Hopefully this post addresses some basic points surrounding chest tube drainage systems! Drop me a comment with questions! 🙂