|Classification and external resources|
Flail chest is a life-threatening medical condition that occurs when a segment of the rib cage breaks under extreme stress and becomes detached from the rest of the chest wall. It occurs when multiple adjacent ribs are broken in multiple places, separating a segment, so a part of the chest wall moves independently. The number of ribs that must be broken varies by differing definitions: some sources say at least two adjacent ribs are broken in at least two places, some require three or more ribs in two or more places. The flail segment moves in the opposite direction as the rest of the chest wall: because of the ambient pressure in comparison to the pressure inside the lungs, it goes in while the rest of the chest is moving out, and vice versa. This so-called "paradoxical breathing" can increase the work and pain involved in breathing. Studies have found that up to half of people with flail chest die.
Flail chest is invariably accompanied by pulmonary contusion, a bruise of the lung tissue that can interfere with blood oxygenation. Often, it is the contusion, not the flail segment, that is the main cause of respiratory failure in patients with both injuries.
Signs and symptoms
The characteristic paradoxical motion of the flail segment occurs due to pressure changes associated with respiration that the rib cage normally resists:
- During normal inspiration, the diaphragm contracts and intercostal muscles pull the rib cage out. Pressure in the thorax decreases below atmospheric pressure, and air rushes in through the trachea. The flail segment will be pulled in with the decrease in pressure while the rest of the rib cage expands.
- During normal expiration, the diaphragm and intercostal muscles relax increasing internal pressure, allowing the abdominal organs to push air upwards and out of the thorax. However, a flail segment will also be pushed out while the rest of the rib cage contracts.
The constant motion of the ribs in the flail segment at the site of the fracture is extremely painful, and, untreated, the sharp broken edges of the ribs are likely to eventually puncture the pleural sac and lung, possibly causing a pneumothorax. The concern about "mediastinal flutter" (the shift of the mediastinum with paradoxical diaphragm movement) does not appear to be merited. Pulmonary contusions are commonly associated with flail chest and that can lead to respiratory failure. This is due to the paradoxical motions of the chest wall from the fragments interrupting normal breathing and chest movement. Typical paradoxical motion is associated with stiff lungs, which requires extra work for normal breathing, and increased lung resistance, which makes air flow difficult. The respiratory failure from the flail chest requires mechanical ventilation and a longer stay in an intensive care unit. It is the damage to the lungs from the flail segments that are life-threatening.
The death rate of patients with flail chest depends on the severity of their conditions ranging from 10-25%.
The most common reason for flail chest injuries are vehicle accidents, which account for 76% of flail chest injuries. Another main cause of flail chest injuries results from falling which is mainly elderly related. The elderly are more impacted by the falls as a result of their weak and frail bones, unlike their younger counterparts who can fall without being impacted as severely. Falls account for 14% of flail chest injuries.
This typically occurs when three or more adjacent ribs are fractured in two or more places, allowing that segment of the thoracic wall to displace and move independently of the rest of the chest wall. Flail chest can also occur when ribs are fractured proximally in conjunction with disarticulation of costal cartilages distally. For the condition to occur, generally there must be a significant force applied over a large surface of the thorax to create the multiple anterior and posterior rib fractures. Rollover and crushing injuries most commonly break ribs at only one point– for flail chest to occur a significant impact is required, breaking the ribs in two or more places. This can be caused by a significant fall, car accident or other forceful accidents. In the elderly, it can be caused by deterioration of bone, although rare. In children, the majority of flail chest injuries can be a result of the common blunt force traumas or metabolic bone diseases, one known as osteogenesis imperfecta.
Treatment of the flail chest initially follows the principles of advanced trauma life support. Further treatment includes:
- Good analgesia including intercostal blocks, avoiding narcotic analgesics as much as possible. This allows much better ventilation, with improved tidal volume, and increased blood oxygenation.
- Positive pressure ventilation, meticulously adjusting the ventilator settings to avoid pulmonary barotrauma.
- Chest tubes as required.
- Adjustment of position to make the patient most comfortable and provide relief of pain.
- Aggressive pulmonary toilet
Surgical fixation can help in significantly reducing the duration of ventilatory support and in conserving the pulmonary function.
A patient may be intubated with a double lumen tracheal tube. In a double lumen endotracheal tube, each lumen may be connected to a different ventilator. Usually one side of the chest is affected more than the other, so each lung may require drastically different pressures and flows to adequately ventilate.
In order to begin a rehab program for a recovery patient with flail chest it is important to treat the patient for pain so the patient is able to perform the proper exercises for recovery. Due the underlying conditions that the flail segment has caused onto the respiratory system, chest physiotherapy is important to reduce further complications. Proper positioning of the body is key, including postural alignment for proper drainage of mucous secretions. The therapy will consist of a variety of postural positioning and changes in order to increase normal breathing. Along with postural repositioning, a variety of breathing exercises are also very important in order to allow the chest wall to reposition itself back to normal conditions. Breathing exercises will also include coughing procedures. Furthermore, range of motion exercises are given to reduce the atrophy of the musculature. With progression, resistance exercises are added to the regimen to the shoulder and arm of the side containing the injury. Moreover, trunk exercises will be introduced while sitting and will progress to during standing. Hip flexion exercises can be done to expand the thorax. This is done by lying supine on a flat surface, flexing the knees and hips and bringing them in toward the chest. The knees should come in toward the chest while the patient inhales, and exhale when the knees are lowered. This exercise can be done in 3 sets of 6-8 repetitions with a pause in between sets. The patient should always make sure to maintain controlled breaths.
Eventually, the patient will be progressed to walking and posture correction while walking. Before, the patient is discharged from the hospital the patient should be able to perform mobility exercises to the core and should have attained good posture.
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