Stage 2 of the study is being conducted at one of the participating sites to determine the initial safety of chronic stimulation of the phrenic nerve in a limited number of patients with sleep disordered breathing. It is anticipated that data obtained in this feasibility study will show that the proposed intervention can modify respiration with a low incidence of adverse effects. The results of this trial are intended to be used to develop a subsequent protocol for a multi-center study of chronic phrenic nerve pacing.