Too much or too little is problematic.

http://www.angio.org/understanding/disease.php

Also....I remember a while back I did some checking into hyperbaric oxygen for a bladder problem John had from his chemo. This was the whole body chamber. Subsequently, I came across hyperbaric treatments for limbs. Never did anything with it but came close to trying the latter for a wound from his hickman port. Pulling the port and surgery fixed it though. Wonder if that has any application for PN?