Response to Diaphragmatic Pacing in Subjects With Pompe Disease

Subjects with Pompe disease who are scheduled to receive a NeuRx Diaphragm pacer (DPS) will
be invited to participate in this study. The following tests will be performed during
participation in the study:

1. Forced expiratory tests

2. Maximal Inspiratory Pressure (MIP)

3. Resting Breathing Pattern

4. Phrenic Nerve Function Evaluation with EMG

5. Severe Respiratory Insufficiency Questionnaire

6. Magnetic stimulation

7. Diaphragm conditioning consisting of:

1. The external stimulator settings

2. The duration of diaphragm stimulation

3. Off-ventilator spontaneous breathing (SB)

Inclusion Criteria:

- Diagnosis of Pompe disease as defined by mutational analysis, GAA enzyme activity
assay in blood spot, and/or fibroblast culture less than 40% of control value

- Medically and functionally eligible for NeuRx DPS implantation, as determined by a
clinical surgical evaluation. The surgeon will determine eligibility through pulmonary
function tests, ability to stimulate your diaphragm, and arterial blood gas levels.
Eligibility may also be determined by your response to traditional respiratory
strengthening exercises without a pacemaker.

- History of mechanical ventilation dependence (six or more hours of invasive or
non-invasive mechanical ventilation support daily for at least 21 days in duration

Exclusion Criteria:

- Current participation in another treatment study (other than enzyme replacement
therapy) directed at improving diaphragm function

- Unable to complete pulmonary function testing