A Portable Oxygen Concentrator for Wound Healing Applications

Abstract

Wound healing is a complex biological process that involves an organized cell assembly leading to tissue regeneration and repair, a process that requires oxygen. As has been reported in many studies, hypoxia delays wound healing; oxygen modulates the inflammatory response of the tissues and it serves as an infection control agent by enhancing the ability of leukocytes to kill bacteria when supplied in adequate amounts. In addition, it promotes collagen synthesis and stimulates angiogenesis. Most importantly, continuous oxygen application leads to wound closure, as has been shown in a number of clinical studies where closure rates as high as 80% have been observed for non-healing recalcitrant wounds. EPIFLO® (Ogenix, Beachwood, OH). (Figure 1) is a commercially available device that can deliver Transdermal Continuous Oxygen therapy and represents an inexpensive alternative to systemic hyperbaric oxygen therapy without the side effects of vasoconstriction, toxicity, and tissue destruction associated with the latter. EPIFLO is a light-weight (~100 g) electrochemical oxygen concentrator with no moving parts and silent operation. It generates continuously 3 mL/hour oxygen (98+% purity) and delivers to the wound site through a cannula tubing. It employs leading-edge oxygen ‘fuel cell’ concentration technology to stimulate tissue regenerative processes driving closure of delayed-healing acute or chronic wounds. This product is US FDA approved for a broad range of indications as a Class II Medical Device; prescribed on order of a physician. It is also CE, ISO 13485:2003 and CMDCAS (Canadian Medical Devices Conformity Assessment Scheme) Health Canada Certified The heart of the device is a Membrane Electrode Assembly (MEA) consisting of a perfluorosulfonic acid cation exchange membrane, such as NafionR, interposed between two high area electrodes made of finely divided Pt based metal catalysts (Figure 2). Atmospheric air composed mostly of ~ 21 % oxygen, 78 % nitrogen is exposed to the device through the slots in the seam formed between the lid and the bottom part of the enclosure, where when activated using a small battery, it promotes the reduction of dioxygen at the cathode and the oxidation of water at the anode to produce oxygen delivered through a suitable tubing to the wound. Since the cation exchange membrane has overall very low gas permeability, gases cannot permeate through the membrane, thus ensuring a higher than 98% purity of the product oxygen. This presentation will describe the critical steps involved in the bench-to-shelf process, invention to product, as well as the highly promising results found from its use in recalcitrant patients.