Diaphragm pacing with a spinal cord stimulator

Background: Diaphragm pacing with electrical stimulation of the phrenic nerve is an established treatment for central hypoventilation syndrome. The device, however, is not readily available. We used the spinal cord stimulator for pain control for phrenic nerve stimulation. Methods: We implanted a stimulator for spinal cord stimulation (Itrel 3 or X-trel, Medtronic, MN) in 6 patients with chronic hypoventilation because of brainstem or high cervical cord dysfunction of various origins. The stimulation electrode was placed along the right phrenic nerve in the neck, and the device was implanted in the anterior chest. We used the cyclic mode, and set the parameters at 1 s ramp up, 2 s on, 3 s off. The pulse width and the frequency were set at 150 mu s and 21 Hz, respectively. The amplitude of the output was adjusted to obtain sufficient tidal volume and to maintain PaCO2 at around 40 mmHg. Results: During the follow-up period up to three years, stable and sufficient ventilation were observed in all patients without complications. One patient with sleep apnea syndrome used the device only at night and became free from a respirator. Three patients who had been completely respirator-dependent became ambulatory during the daytime. Conclusion: Though longer follow-up is necessary, diaphragm pacing with the spinal cord stimulator is feasible for a treatment of central hypoventilation syndrome.