What serious respiratory issue can arise from injuries at or above C3-C4?

Injuries at or above the C3-C4 vertebrae can severely impact respiratory function due to the involvement of the phrenic nerve, which is responsible for diaphragmatic movement. The diaphragm is the primary muscle used for breathing, and injury at these levels can lead to paralysis of this muscle, resulting in inadequate ventilation and respiratory failure.

Individuals with such high cervical spine injuries may not be able to initiate breaths on their own, leading to a critical lack of oxygenation. This requires immediate medical intervention, often including assisted ventilation or intubation to sustain respiratory function. In this context, the term "respiratory issues" accurately encompasses the range of complications that can arise from such injuries, including inadequate breathing, reliance on mechanical ventilation, and an increased risk of further respiratory complications.

While aspiration and pneumonia are indeed significant concerns in patients with severe respiratory compromise, they are typically secondary issues related to the primary failure of respiratory function. Cardiac arrest, although a possible event due to profound hypoxia or other causes, is not a direct respiratory issue stemming from the spinal injury itself. Therefore, the focus on broad respiratory issues is most representative of the critical consequences of injuries occurring at or above the C3-C4 level.