Respiratory complications in spinal cord injury
In acute and chronic spinal cord injury there are several respiratory complications to be aware of, but before we look at what can go wrong let us first look at the functioning of a normal tract.
The normal respiratory tract
The respiratory system comprises the upper and lower airways. The upper airways comprising the nose are important for humidification while the lower respiratory system (the airways and lungs) are important for the oxygenation of the blood. In a body functioning normally, the air is drawn into the lungs by a combined effort of the small muscles between the ribs (12 intercostal muscles) that expand the rib cage and the downward movement of the diaphragm, the large muscle at the bottom of the lungs. This draws air into the lungs and allows for the blood to be oxygenated. When excessive phlegm builds up, a cough is generated by a combined contraction of the intercostals, diaphragm and abdominal muscles to expel the phlegm.
Problems with neurological compromise
In the acute spinal cord injured person who has an injury above T12, there will always be some compromise of the normal functioning of the respiratory system. The muscular diaphragm derives its nerve supply from nerves which exit the spinal cord at C3, C4 and C5. Any injury at this level or higher compromises the normal functioning of the diaphragm and athere may be need for a permanent ventilator, as was the case with the actor Christopher Reeves (Superman). The intercostal muscles each receive a nerve supply from the corresponding thoracic spinal nerves T1 to T12. Therefore, any injury at any of these levels will cause paralysis of the muscles below. For example if a spinal cord injury is at T2, then all the intercostal muscles below T2 are non-functional. The only muscles of respiration that work effectively are the T1 intercostal and possibly T2 and, of course, the diaphragm. After spinal cord injury the greatest problem is the effectiveness of breathing. For tetraplegic and paraplegics with a very high lesion, the only muscle supporting respiration is the diaphragm. In the acute stage this muscle may become fatigued and this leads to respiratory failure and the need for short-term ventilation. Complicating this fatigue is the inability to expel phlegm effectively leading to retained secretions and possible infections. Aggressive respiratory support is necessary in the acute stage. For lower lesions, this becomes less significant as some of the intercostals still assist with breathing.
The greatest problem in both acute injuries and chronic injuries is a poor, or weak cough due not only to intercostal muscle paralysis, but often the loss of the abdominal muscles. Therefore, it is therefore important to effectively manage secretion build-up and often assisted coughing is required. An assistant would need to help with effective coughing by placing pressure over the diaphragm and assisting with the expulsion of retained secretions. These techniques are normally taught to care givers in the acute rehabilitation phase and should be used whenever needed. This will assist with the expelling of phlegm and deceasing the risk of infection.
Another common complaint amongst tetraplegics is a blocked nose – this occurs especially in the acute phase. The phenomenon is due to the dilation of the small vessels in the nose (known as Guttmann’s sign). It responds well to vasoconstrictors such as Iliadin nasal spray, but this should be used sparingly as overuse can cause other problems.
Because the spinal cord injured person is susceptible to secretion build up, infections can occur more commonly. I would advise patients at high risk to get a flu injection every year. It will at least immunise you against the common flu strains around. However, if you do get flu, antibiotics are not necessarily the answer. Flu germs are normally viruses which do not respond to antibiotics. Remember to get frequent help to cough out secretions and use a good expectorant syrup and bronchodilator if you are wheezing. Chest physiotherapy is important if you develop a chesty cough. One should only resort to antibiotics if it is a bacterial infection diagnosed by your doctor.
The best advice I can give to anyone, especially spinal cord injured persons is do not further compromise your lungs by smoking. If you do smoke, try to reduce the amount of cigarettes per day, and as this will not only help in preventing spinal-related complications but also life-threatening cancers.