I see it's being prescribed, and to a small-ish number of people (400), so perhaps it's in a trial phase? FDA has 5 phases for medical device development (googled below):

    Step 1: Device Discovery and Concept.
    Step 2: Preclinical Research-Prototype.
    Step 3: Pathway to Approval.
    Step 4: FDA Device Review.
    Step 5: FDA Post-Market Device Safety Monitoring.

They could be on step 3, where they do clinical trials. Maybe working with the VA, or perhaps they advertised at VA hospitals or veteran's groups. I would imagine that's the easiest group to find and recruit into your trial.