The pleural cavity is a closed, potential space located between the visceral pleura, which covers the lungs, and the parietal pleura, which lines the inner chest wall. Normally, this space contains only a few milliliters of serous fluid that acts as a lubricant, allowing the lung membranes to glide smoothly during respiration. Under physiological conditions, the pressure within the pleural space is negative relative to atmospheric pressure. This constant negative pressure acts like a suction force that keeps the elastic lungs expanded against the chest wall.
When air, blood, or fluid enters this potential space, the normal negative pressure is lost. The expanding pressure pushes against lung tissue, causing it to collapse partially or completely. Midwives and nurses caring for obstetric and general surgical patients must recognize that any disruption to this delicate pressure balance impairs gas exchange and requires rapid intervention to restore normal respiratory mechanics.
A chest tube is inserted into the pleural cavity to drain abnormal accumulations of air, fluid, or blood, thereby re-establishing negative pressure and allowing the lung to re-expand. Common clinical scenarios requiring this intervention include:
Traditional chest drainage systems utilize a three-chamber setup to manage air and fluid removal safely. Understanding these chambers helps prevent common errors in clinical practice.
| Chamber Name | Primary Function | Normal Observation |
|---|---|---|
| Collection Chamber | Receives fluid and air from the patient's pleural cavity | Gradual accumulation of drainage; measured hourly or daily |
| Water Seal Chamber | Acts as a one-way valve allowing air to exit while preventing backflow | Tidalling (water level rises and falls with breathing) |
| Suction Control Chamber | Regulates the amount of negative suction applied to the system | Continuous gentle bubbling (wet system) or a float indicator (dry system) |
The under-water seal is the critical safety feature. It allows air to bubble out of the patient's chest when they exhale or cough, but the water barrier prevents outside air from being sucked back in when the patient inhales.
Maintaining a closed, functioning chest drainage system requires consistent vigilance. The entire apparatus must remain below the level of the patient's chest at all times to prevent gravity-driven backflow of fluid or water seal liquid into the pleural space.
Check all connection sites frequently to ensure they are securely taped and leak-free. Tubing should be coiled loosely on the bed or floor; avoid dependent loops or kinks that can trap drainage and obstruct airflow. Stripping or milking chest tubes is generally discouraged because it creates dangerously high negative pressures that can damage fragile lung tissue. Always keep two rubber-tipped hemostats, sterile water, and extra sterile dressings at the bedside for emergency use.
Effective monitoring involves assessing both the patient and the drainage equipment. Observe the character and amount of drainage regularly; a sudden surge of bright red blood exceeding 100 mL per hour should be reported immediately as potential hemorrhage.
Assess for tidalling in the water seal chamber. If tidalling stops unexpectedly, it usually means either the lung has fully re-expanded and the pleural space is healed, or there is an obstruction like a blood clot or a kink in the tubing. Continuous bubbling in the water seal chamber indicates an air leak, which must be tracked down systematically. Finally, always monitor the patient's vital signs, oxygen saturation, and respiratory effort to evaluate clinical recovery.
Chest tube complications can escalate rapidly into life-threatening emergencies if staff do not act with clear protocols.
Chest tubes are removed when the underlying pathology has resolved. Standard criteria include minimal fluid drainage (typically less than 50 to 100 mL per 24 hours), absence of bubbling in the water seal chamber during coughing, improved breath sounds, and full lung re-expansion confirmed on a chest X-ray.
The removal procedure is a sterile, coordinated task. Explain the procedure clearly to the patient. Pre-medicate for pain about 30 minutes beforehand as ordered. Gather suture removal kits, petroleum gauze, and occlusive tape. Instruct the patient to take a deep breath, hold it, and bear down (Valsalva maneuver) while the clinician swiftly pulls the tube out. This maneuver increases thoracic pressure and prevents air from entering the pleural space during removal. Immediately apply the airtight dressing, and obtain a follow-up chest X-ray to verify lung stability.