The first priorities for the person with spinal cord injury are to maintain life and stabilize the spine and to treat any coexisting injuries or medical problems. After these priorities have been addressed, a number of other medical interventions and treatments come into play. Some are necessary only in the early days of hospitalization, while others are required either continuously or periodically.
The diaphragm is the main muscle for inhaling air: contraction of the diaphragm sucks air in but does not push it out. The chest is elastic and springs back into place when we stop breathing in, and as the chest springs back, air is naturally pushed out of the nose and mouth. The muscles of the chest and abdomen allow us to exhale air forcefully, as in coughing, shouting, or clearing the throat.
The diaphragm receives its nerve supply primarily from the C4 level of the spinal cord via the phrenic nerve. Spinal cord injury affecting the C4 level or above can cause permanent weakness or paralysis of the diaphragm, so that the injured person cannot breathe. A mechanical ventilator is then needed to pump air into the lungs, substituting for the diaphragm.
An endotracheal (breathing) tube carries the air from the ventilator into the lungs, and a tracheal suction tube is used to clear phlegm from the windpipe. The endotracheal tube temporarily makes speaking impossible, and if left in place too long it can damage the larynx (voice box). Damage to the larynx can be prevented by a minor operation called a tracheostomy, the formation of a small opening in the front of the neck that allows air to enter the windpipe directly. The tracheostomy is usually held open with a small plastic tube.
Several different types of tracheostomy tubes are available. Some include a small plastic cuff in the windpipe that directs air into the lungs and prevents it from leaking out of the nose and mouth. This is important to provide adequate airflow to the lungs, especially during surgery when the patient may be unconscious. The problem with this cuffed tracheostomy tube is that it generally makes speech impossible. When the individual exhales, all the air flows out through the tracheostomy tube and none through the larynx. If a cuffless tracheostomy tube is inserted, airflow through the larynx is possible. Individuals who require long-term use of a tracheostomy tube or a mechanical ventilator can usually learn to speak with a cuffless tracheostomy tube and special techniques for breathing and speaking. This often requires the use of a tracheostomy speaking valve, which helps to direct airflow through the larynx. If the strength of breathing muscles improves, the tracheostomy is easily reversed by simply removing the tube and allowing the opening to heal.
After use of a mechanical ventilator for more than a day or two, the resumption of independent breathing may be difficult. This problem is handled by a process called ventilator weaning. During the weaning process, the amount of respiratory support provided by the ventilator is gradually reduced, and the individual is permitted to have short periods of time off the ventilator. These periods are gradually increased until the ventilator is no longer necessary.
People with permanently paralyzed breathing muscles must use a ventilator for the rest of their lives. This is especially common in cervical spinal cord injuries. (Some people with lower spinal cord injuries also need a ventilator, if only temporarily.) Thus breathing is a focal point of treatment for many people with spinal cord injury. Long-term dependence on a ventilator has a significant effect on mobility and can require attendant care, and it may affect psychological adjustment.