An open pneumothorax is a life-threatening medical emergency caused by a penetrating injury to the chest wall. Often called a “sucking chest wound,” this condition results in a collapsed lung that has a direct pathway to the outside air. The severity depends on the size of the wound, which allows outside air to rush into the chest cavity with every breath. Immediate recognition and action are necessary for survival as this injury rapidly impairs the body’s ability to breathe.
Mechanism and Causes of an Open Pneumothorax
The chest cavity normally maintains a negative pressure relative to the outside atmosphere, which is essential for the lungs to inflate during inhalation. An open pneumothorax occurs when a defect in the chest wall, such as a large wound, compromises this sealed system. Air from the outside environment then enters the pleural space, neutralizing the necessary negative pressure. This equalization prevents the lung on the injured side from fully expanding, leading to a partial or complete collapse.
The primary causes are traumatic, involving a penetrating force that breaches the rib cage and surrounding tissue. Common incidents include stab wounds, gunshot injuries, impalement from accidents, or severe blunt trauma resulting in a jagged open wound. When the chest wall opening is sufficiently large, air preferentially enters through the wound rather than the trachea, severely limiting the oxygen that can reach the blood.
Recognizing the Symptoms
Recognizing the signs of an open pneumothorax is time-sensitive. The most characteristic symptom is the physical sound of air moving through the wound, often described as a distinct “sucking” or “hissing” sound as air rushes in and out of the chest cavity. The patient will exhibit severe shortness of breath (dyspnea) and visible distress as they struggle to take effective breaths.
Bubbling or frothing may also be observed at the wound site, caused by air mixing with blood or fluid. In severe cases, a bluish tint to the skin, lips, or nail beds, known as cyanosis, may develop due to low blood oxygen levels.
Immediate Pre-Hospital Action
The first step in managing an open pneumothorax is immediately calling for emergency medical services. While waiting for professional help, the goal is to seal the wound to prevent more air from entering, while still allowing trapped air to escape. This is accomplished by applying a three-sided occlusive dressing, which can be a commercial chest seal or a makeshift seal using sterile plastic or waterproof material.
The dressing should be secured to the skin on three of its four sides, leaving the fourth side unsealed and pointing downward. This design creates a flutter valve effect, permitting air that has already entered the pleural space to exit during exhalation, but preventing outside air from being sucked in during inhalation. If a foreign object is impaled in the chest, it must not be removed; instead, stabilize the object with bulky dressings. Positioning the patient, ideally in a sitting or semi-sitting position, can also help ease breathing.
Definitive Medical Treatment
Definitive medical treatment begins once the patient is in the care of professionals. The primary procedure is the re-establishment of negative pressure within the pleural space, which is necessary for the lung to fully re-inflate. This is most commonly achieved through the insertion of a chest tube, known as tube thoracostomy. The tube is placed into the chest cavity to continuously drain accumulated air and fluid, allowing the collapsed lung to expand.
The chest tube is connected to a one-way valve system that maintains negative pressure and prevents the re-entry of atmospheric air. Once the chest wall injury is sealed and the lung has re-inflated, the wound itself is closed and surgically repaired. If the initial injury is extensive, or if there are persistent air leaks or significant internal bleeding, a more extensive surgical procedure called a thoracotomy may be necessary to directly repair the lung tissue or chest wall.