A cause of paradoxical breathing that can be either traumatically or medically induced is paralysis of the diaphragm.
In this very rare condition, the diaphragm could be paralyzed or weakened by damage to the spinal cord or by a medical cause directly affecting the muscle or the nerves running from the brain to the diaphragm.
The diaphragm is a domed muscle at the base of the chest cavity that separates it from the abdominal cavity. The diaphragm is extremely important in breathing. It’s the muscle most involved in expanding and contracting the chest cavity to change volume with inhalation or exhalation.
When the diaphragm is sufficiently weak, the muscles of the chest wall—the intercostal muscles—must do all the work of breathing. Even when these muscles are engaged during periods of exercise or shortness of breath, the diaphragm is a stabilizing force and assists with movement of the chest cavity.
If the diaphragm is too weak to stabilize the base of the chest cavity, chest movement can pull abdominal organs toward the chest when you inhale and push them away from the chest when you exhale.
As the chest expands, abdominal organs move up and seemingly behind the sternum, causing the abdominal wall to contract. When the chest contracts for exhalation, the organs are pushed away and the abdominal wall expands.
Paradoxical breathing from a weak or paralyzed diaphragm often gets worse when you lie flat on your back (supine) and appears to resolve when you stand up.