Check out the recent review paper from Northwestern University on the effects of Blood Flow Restriction for muscle mass and strength. The paper is open access and includes a video on the application of BFR. Here is the conclusion from the publication.

"Blood flow restriction training is an effective alternative to high-load resistance training for patients requiring musculoskeletal rehabilitation for multiple disease processes as well as in the perioperative setting. Blood flow restriction has been shown to be a safe training modality when managed by properly trained physical therapists and athletic trainers."

The full text and the video can be found at the publication site.