Phrenic nerve stimulation for diaphragm pacing with a spinal cord stimulator: technical note

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, at least in Japan. We used the spinal cord stimulator for pain control for phrenic nerve stimulation. The purpose of this study is to evaluate the efficacy and feasibility of phrenic pacing with the compromise method. METHODS: We implanted a stimulator for spinal cord stimulation (Itrel 3 or X-trel, Medtronic, MN) in 4 patients with chronic hypoventilation because of brainstem 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 second ramp up, 2 seconds on, 3 seconds off. The pulse width and the frequency were set at 150 microsec and 21 Hz, respectively. The amplitude of the output was adjusted to obtain sufficient tidal volume and to maintain PaCO(2) at around 40 mm Hg. RESULTS: During the follow-up period from 6 to 19 months (mean 8.3 months), 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 were completely respirator-dependent became ambulatory during the daytime. CONCLUSION: Though longer follow-up is necessary, diaphragm pacing by stimulation of the phrenic nerve with the spinal cord stimulator is feasible for a treatment of central hypoventilation syndrome.