hypoxia preconditioned plasma hypoxia preconditioned plasma hypoxia preconditioned plasma or hypoxia pre-conditioned plasma (abbreviated as hpp) is the (cell-free) plasma obtained after extracorporeal conditioning (i.e. culturing) of anticoagulated blood under physiological temperature (37 °c) and physiological hypoxia (1–5 %o2). blood conditioning is typically carried out over 2 to 4 days. image of a prototype bioreactor device for one-step preparation and sampling of hypoxia preconditioned plasma (hpp) no high quality evidence supports its use for any medical purpose as of 2016.