Final answer:
A cervical spine collar should never be used as the only immobilization device for a known spinal injury patient.
Step-by-step explanation:
When dealing with a known spinal injury patient, it is never appropriate to use a cervical spine collar as the only immobilization device. This is because a cervical spine collar alone does not provide adequate immobilization and protection for the spine. Instead, it is necessary to keep the person very still, place heavy towels on both sides of the neck or hold the head and neck, and prevent any movement until emergency care arrives.