The respiratory system, also known as the pulmonary system, is used for breathing. The windpipe and lungs are the two main parts of the respiratory system. When you inhale, or breathe air in through your mouth or nose, oxygen travels down your windpipe and into your lungs. Your lungs then filter the oxygen and send it through your blood stream to all of your body parts. When you breathe out, or exhale, you send the leftover carbon dioxide out of your body, through your windpipe and out of your mouth or nose.
When you exhale, it does not require any effort from the body’s muscles. However, you normally use a combination of four respiratory muscle groups to breathe air into your body. The diaphragm, a strong, dome-shaped muscle that separates the abdominal and chest cavities, is normally the main muscle that you use when you inhale. The intercostal muscles are located between the ribs. These muscles help to expand your ribs as you inhale. The neck muscles normally work to expand your upper chest when inhaling. The abdominal muscles work with these other muscle groups to help you breathe deeply and cough.
The brain normally sends signals through nerves in the spinal cord to control the four respiratory muscle groups. When everything is working properly, the pulmonary system and respiratory muscles work together allowing you to breathe in and out without much effort. In fact, most people breathe without ever thinking about it.
The windpipe and lungs are not typically affected by a spinal cord injury. However, respiratory problems may occur when the signals sent from the brain can no longer flow through the spinal cord to control the respiratory muscles. The amount of muscle control that is lost after a spinal cord injury depends on the level of the injury, along with the completeness of the injury.
Individuals with injuries below the T12 level do not usually lose any control of the four respiratory muscle groups needed for breathing. This means the respiratory system is not usually affected by injuries in the lumbar or sacral regions of the spinal cord. Individuals with complete thoracic or cervical injuries do experience a loss of their respiratory muscle control. The higher the level of injury, the greater the loss of respiratory muscle control.
Complete injuries in the thoracic or cervical regions usually result in the permanent loss of respiratory muscle function below the level of injury. However, if that injury is incomplete, it is impossible to predict whether individuals will regain some or all of their respiratory function below the level of injury. Injuries in the thoracic area (T1-T12) of the spinal cord affect the control of the intercostal and abdominal muscles. A lower level of injury, such as a T10, results in the individual losing a small amount of muscle control. With a higher level of injury, such as a T2, individuals will lose most of their intercostal and abdominal muscle control. Complete injuries in the cervical region usually result in a total loss of intercostal and abdominal muscle control.
Again, the higher the level of injury, the greater the loss of additional muscle controls. For example, a complete injury between levels C3 and C5 loses all control of the diaphragm muscles. With a complete injury at level C3 and higher, the individual loses control of all four muscle groups that are needed for breathing. A ventilator is then needed to assist in breathing. The ventilator does the work of the absent muscles and forces air into the lungs. Many people with a C4 level of injury, and even some people with a C3 level of injury, can eventually breathe without the aid of a ventilator or may only need it for part-time assistance. Those individuals with complete injuries above C3 need a ventilator for full-time assistance.
Individuals with a spinal cord injury are at increased risk for developing respiratory complications. Any loss of respiratory muscle control weakens the pulmonary system, decreases one’s lung capacity, and increases respiratory congestion. It does not matter what the level of injury is or if the injury is complete or incomplete. However, the risk for complications is greater for individuals with a complete injury and for persons with tetraplegia.For persons with high level tetraplegia (C5-C1), ventilatory failure is a common complication after injury. The person typically lacks the ability to breathe without assistance.
Another common problem is atelectasis. This is when the lungs partially collapse because not enough air is getting into them.
Persons with all levels of injury are at risk for pulmonary embolism. Pulmonary embolism is a blockage in the blood vessels of the lungs by a blood clot, and it is the second leading cause of death for persons with SCI within the first year after their injury. In addition, individuals with high tetraplegia (C1-C4) are about 100 times more likely to die from diseases of pulmonary circulation, regardless of time after injury, when compared to the general population. Those individuals with paraplegia (T1-S5) are almost 50 times more likely to die from pulmonary embolism. Ventilatory failure, atelectasis and pulmonary embolism are all very serious, life-threatening respiratory complications.
However, pneumonia is the leading cause of death for all persons with spinal cord injury. This is true regardless of your level of injury or how long you have been injured. Be aware of the symptoms for pneumonia. They include shortness of breath, having pale skin, a fever, along with a feeling of heavy chest, coughing, and an increase in congestion. If you have symptoms of pneumonia, call a doctor immediately for advice on treatment.
PREVENTION OF RESPIRATORY COMPLICATIONS
- Because persons with SCI are more likely to develop respiratory complications within the first year after injury, it is very important to take steps to prevent complications during the acute care and rehabilitation stays.
- Treat all symptoms of respiratory complication aggressively to help prevent further complications from developing.
- Individuals with SCI should receive a yearly vaccination for (pneumococcal) pneumonia and influenza.
- Avoid the buildup of secretion in the lungs. It can be helpful for persons with high level tetraplegia to receive regular treatments with a cough assist machine. Individuals with tracheotomies who are on a ventilator need to have secretions suctioned from their lungs on a regular basis