1996 OPEN FORUM Abstracts
Cervical Spinal Cord Injury
Charles G. Durbin, Jr., MD Monday, November 4, 1996
Respiratory difficulties and failure often follow cervical cord injury. Identification of the patient at risk and provision of early supportive treatment may improve outcome, shorten hospital stay, and allow earlier entry into rehabilitation. The respiratory effects of spinal cord injury vary with the level of the injury, the severity of the injury (complete versus incomplete), associated physical injuries, and the presence of underlying pulmonary diseases.
Breathing difficulty at the time of injury is not generally seen if the level of injury is C-5 or lower, as the phrenic nerve originates from the third through fifth cervical roots. 70% of the predicted vital capacity is usually present with a C-5 level cervical injury. If acute respiratory failure occurs at the time of injury, there may be a higher cervical injury or another cause of failure. Pulmonary contusion, pneumothorax, flail chest, or pre-existing chronic lung disease may be the cause of respiratory distress. Apnea will occur if a complete cord injury occurs at C-3 or above. These patients will rapidly succumb if artificial ventilation is not provided at the time of the injury. Patients with injuries between C-5 and C-3 will have some respiratory embarrassment and may require ventilatory support early in their treatment. A falling vital capacity, negative inspiratory pressure and increasing respiratory rate may signal the need for intubation on non-invasive ventilation.
If a patient with a cervical cord injury avoids intubation early in their course, they are still at risk for respiratory failure. Airway clearance requires a good cough. Although exhalation is passive, cough is active. Most of the pressure generated during a cough comes from active contraction of the abdominal muscles. These muscle groups are lost in cervical cord injuries. Cough is ineffective. "Quad-coughing" is a technique that can be used to help mobilize secretions in these patients.
Patients with a smoking history are especially at risk of respiratory failure after a cervical cord injury. This is because of increased secretions leading to atelectasis and pneumonia. Secretions coupled with a poor or absent cough is a bad combination. Patients with other pulmonary diseases may also experience respiratory failure after less significant cord injuries. Patients with asthma and COPD fall into this risk category.
The functional level of the cord injury may rise after the initial event. This may be due to a hematoma or cord edema. Steroids have been used to reduce edema and may result in a better functional outcome. Immobilization is essential to prevent further trauma at the injury site. Traction is used to realign a fracture.
Intubation is complicated by the need to maintain spinal immobility during laryngoscopy. Inline traction provided by a second person is the preferred method. Nasal intubation may require less neck movement than the oral route, however, there is probably a higher incidence of sinusitis over time. Two other problems with quadriplegia are GI bleeding and venous thromboembolism. Prophylactic measures for each of these should be taken. Nutritional support must be addressed early in the course of the injury.
The best respiratory outcome can be achieved by identifying the high risk patients, taking preventive measures, initiating respiratory support early in respiratory failure, optimizing nutrition, and preventing complications.