Edgelow - it's named after a PT guy (Peter Edgelow) that used it as a main focus of his PT protocol. He's retired now.
I haven't done or studied his specific plan, but I believe it is very similar to diaphragmatic breathing also called belly breathing.
Probably easiest to get the details by watching some you tube videos that show how to do it.
The basic idea is that when stressed, or in pain, we limit our breathing to the upper lungs - which limits oxygen intake as well as making for a shallow exhale breath, which is when the "air type toxins" are expelled from the body.
diaphragmatic breathing -
https://www.google.com/search?q=diap...-a&channel=rcs
http://www.youtube.com/results?q=dia...-8&sa=N&tab=w1