Injury to the spinal cord or brain stem may damage the nerve cells that stimulate the phrenic nerve, which facilitates contraction of the diaphragm necessary for breathing. Phrenic nerve pacing, which uses and electrode implanted in the chest to stimulate the phrenic nerve, may benefit certain patients who are dependent on a respirator. If your doctor believes that you may be a good candidate for this procedure, he or she may order tests called phrenic nerve EMGs. These tests will usually indicate if phrenic nerve pacing is possible for you. The equipment required for phrenic nerve pacing is much smaller and more portable than a mechanical ventilator.

Phrenic nerve pacers improve respiratory physiology because air is drawn into the lungs naturally by diaphragmatic contractions, rather than air forced into the lungs under pressure form a mechanical ventilator.