[Transport of severely injured trauma patients in an ambulance with and without a rigid neck orthosis: comparative biomechanical measurements].

Background: The actual significance of prehospital immobilization of the cervical spine in severely injured trauma patients remains unclear. In view of possible negative implications, such as an increase in intracranial pressure due to the application of a rigid cervical spine orthosis, the long-term use must be critically questioned. Further studies are required to justify the long-term use of a rigid cervical spine orthosis in the prehospital setting.

Objective: Comparative measurements of the mobility of the cervical spine during immobilization using a vacuum mattress with or without the additional application of a rigid cervical spine orthosis after positioning on the stretcher were carried out.

Material and methods: Biomechanical measurements of the movement of the cervical spine were carried out by attaching inertial measurement units to a test person during the loading and unloading process in a modern ambulance and during the journey along a predefined parkour. The test person on whom the measurements were carried out was immobilized on a vacuum mattress with the option of lateral fixation of the head and chin and forehead strap on an electrohydraulic stretcher. The complete standard monitoring was set up to simulate as realistic a transport of a severely injured patient as possible. A total of 30 test runs were realized. In one half of the tests, the cervical spine was additionally immobilized using a rigid orthosis and in the other half a cervical spine orthosis was not used. For each of the 30 tests, the angles, axial rotation, lateral bending and flexion/extension as well as the first and second derivatives were considered for loading, transport and unloading and the parameters mean deviation from the zero position, size of the swept angle range and maximum were calculated for each test run.

Results: Statistically significant differences were only found for some biomechanical parameters in the sagittal plane (flexion and extension). No significant differences were found for the measured parameters in the other directions of movement (axial rotation, lateral flexion). In general, only very small angular deflections were measured both in the tests with the cervical spine orthosis and without the cervical spine orthosis (on average in the range of 1-2° for axial rotation and flexion/extension and up to 3° for lateral flexion).

Conclusion: If immobilization is carried out correctly using a vacuum mattress with the option of lateral stabilization of the head and chin and a forehead strap on an electrohydraulic stretcher with a loading system, there are no relevant advantages with respect to the restriction of movement of the cervical spine by the additional use of a rigid cervical spine orthosis for the loading and unloading process or during the transport in a modern ambulance. It could therefore be advantageous to remove the rigid cervical spine orthosis initially applied for the rescue of the patient at the scene after the patient has been positioned on the vacuum mattress and stretcher to avoid potential negative effects of the rigid cervical spine orthosis for the period of transportation to the hospital.