Study Design.
A retrospective study of 36 patients with mid- to lower cervical spinal cord injury (CSCI) divided into two groups based on whether delayed apnea developed.
Objectives.
To determine nonpulmonary risk factors associated with the development of delayed apnea in mid- to lower cervical spinal cord injury.
Summary of Background Data.
Patients with mid- to lower cervical spinal cord injury are generally at lower risk of developing respiratory failure than those with high cervical spinal cord injury. Respiratory failure manifesting as sudden apnea may occur days or even weeks after injury without any pulmonary complications in such patients.
Methods.
An index group of eight patients with complete mid- to lower cervical spinal cord injury in whom delayed catastrophic apnea occurred were reviewed. Another group of 28 patients with cervical spinal cord injury of identical magnitude and presentation but without respiratory failure served as the control group. Six parameters presumed to be related to the delayed apnea were analyzed.
Results.
The extent of cord lesions was significantly different, being diffuse in most of the index patients, but focal in the majority of the control patients (P < 0.001). Involvement of the C4 segment of cord appeared to be more frequent in the index group; however, the difference was not statistically significant (P = 0.091). The incidence of transient bradycardia (P < 0.01) and dyspnea (P < 0.001) in the index group was significantly higher than in the control group. Paralytic ileus was a much rarer event and found to be unrelated to the occurrence of apnea. In five of the eight index patients, the apnea occurred during sleep. Six of the eight index patients died of it.
Conclusions.
Delayed but devastating apnea may develop in patients with mid- to lower cervical cervical spinal cord injury, even when they are clinically stable and free from any pulmonary complications. The presence of diffuse, extensive cord lesions, respiratory distress, or bradycardia with or without associated hypotension, however transient and self-limited, should be regarded as warning signs. Sleep was found to be a risky period of time.
