Take a deep breath and notice that your chest expands as you fill your lungs with air. Paradoxical breathing describes an abnormal chest movement, with your chest moving inward during inhalation rather than outward. This abnormal movement impairs the ability to effectively inhale, limiting the amount of oxygen you can take in. Blood oxygen levels drop and carbon dioxide levels increase, because this metabolic byproduct cannot be exhaled adequately. Various types of medical problems can lead to paradoxical breathing by disrupting different aspects of the mechanics of normal breathing.
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If your airway is partially or fully obstructed, it is difficult for your lungs to move air in and out. When you attempt to breathe in, your diaphragm -- the main muscle of breathing -- lowers, attempting to inflate your lungs. If air cannot pass by a blockage in your airway, your chest wall moves inward rather than outward. This can occur in obstructive sleep apnea, when the soft tissues of the throat block your airway. The same mechanics occur with a blockage due to a foreign object. This paradoxical movement is also common in end-stage chronic obstructive pulmonary disease due to poor airflow and weakness of the respiratory muscles.
Mechanical Disruption of Chest Wall
Paradoxical breathing may also be related to trauma, such as a motor vehicle accident. Flail chest results when a section of the ribs separate from the rest of your chest wall, as occurs when several ribs are broken. The separated section does not expand with the rest of the chest when inhaling. Instead, it is pulled inward, which negatively affects your ability to breathe normally. A pneumothorax, or a collapsed lung, also often occurs as a result of injury or trauma. Air leaks into the area between the chest wall and your lung, causing collapse of the affected portion of your lung. A paradoxical breathing pattern often results.
Your diaphragm is below your lungs and separates your chest cavity from your abdomen. The muscular contractions of the diaphragm are controlled by the phrenic nerve. Normally, the diaphragm contracts and flattens on inhalation. This causes the abdomen to expand outward as your lungs fill with air. When the phrenic nerve is damaged or fails to work properly because of a medical condition, the diaphragm is paralyzed and paradoxical breathing results. With a paralyzed diaphragm, your abdomen retracts inward during inhalation. Possible causes of a paralyzed diaphragm include spinal cord injuries, lung cancer, multiple sclerosis and muscular dystrophy.
Seeking Medical Attention
The disruption of normal breathing patterns caused by paradoxical respiration can be life threatening. If you experience paradoxical breathing or suspect you may have obstructive sleep apnea, see your doctor right away. Emergency attention is needed if you believe you have flail chest or a pneumothorax. If a foreign object is obstructing the airway, call 911 and have someone try the Heimlich maneuver to dislodge the blockage.