ate their secondary disabilities. In individuals with chronic spinal cord injuries, as in the able-bodied population, the common causes of morbidity and mortality are pulmonary and cardiovascular diseases. For example, Gale Whiteneck has found that, similar to the able-bodied population, cardiovascular disease is a leading cause of death in those with spinal cord injuries (Whiteneck et al., 1992). He and his colleagues have reported that among individuals who survive more than 30 years after their injury, 46 percent of all deaths are the result of a fatal cardiovascular event; among those older than 60 years, cardiovascular disease is responsible for 35 percent of all deaths. Heart and lung diseases may not be an immediate cause of death, but they potentially cause further functional impairment and require additional expenditures of resources in those with greater disabilities.
Individuals with spinal cord injuries are classically described as having restrictive ventilatory dysfunction, although in those with higher cord lesions, there is also evidence of airflow obstruction. The higher the spinal cord lesion that an individual has, the greater compromise of the muscles of respiration and the more difficult it is to breathe and cough effectively. If cough is reduced or absent, the clearance of secretions is impaired, which, in turn, can lead to atelectasis and, possibly, pneumonia. Those individuals who have lesions that are at thoracic level 4 or higher have been reported to have an ability to forcibly exhale that falls below the normal range, as evidenced by a forced vital capacity below 80 percent of the levels predicted for able-bodied subjects matched for age, gender, race, and height (Figure M-1).