A medical device having a permeable bag connected by a non-permeable cannula to a discharge sac is described along with a manufacturing process and surgical implantation method. The permeable portions of the device have pores that are sized to be permeable to a predetermined class of small molecules, such as oxygen, nitrous oxide, or other therapeutic agents. Once absorbed inside the device, the small molecules are then passively transported, by a concentration gradient of the small molecules, to the discharge sac to be disbursed. A metal tube or other strip can be included in the cannula to assist a surgeon in orienting the device within the body.