I've played with a hospital grade oxygen mask, very similar to the pic, on the Volcano Digit with a very small bag maybe 100-200ml capacity. It was good, I can see it being of real benefit to immobile patients and I think it would do a lot for credibility and public acceptance of vaporization in a medical scenario.
The sound of the Volcano bag is starting to shit me that's the main reason I had a play with it. It's good, but I think you really need an inline bag or resevoir with enough volume depending on rate of airflow and pressure - probably should be custom designed to take into account your vape's capabilities, and yeah my ghetto rig was very unstable and top-heavy so you had to hold the valve down on the Volcano or it would tip over.
I reckon it's worth pursuing for patients and the elderly, but yeah it would need to be properly designed. A vape with variable airflow would be ideal, the Digit's pump seemed way too fast without having a huge bag and then what's the point really. Fun though