| Background:Negative pressure Wound therapy (NPWT) is a efficacious wound treatment that applies negative pressure to the wound bed to promote healing in acute and chronic wounds. In practice, NPWT technique involves using a polyurethane (PU) or polyvinyl alcohol(PVA) foam dressing as a wound interface layer, placing multi-side hole drainage tube, and covering it with a semipermeable membrane to create an air-tight seal. On formation of an efficient drainage system, multi-side hole drainage tube was connected to vacuum pump. All of these studies demonstrated that NPWT early closured wound, maintained vacuum state, and reduced the bacterial burden of wounds. NPWT promotes maximum tissue in growth and facilitates the extraction of fluid from the wound. The open cell design allows all pores in the foam to communicate. NPWT applied to a wound surface has been demonstrated to have the following micro and macro-mechanisms of action:increases local blood flow to wounds; reduces edema; stimulates formation of granulation tissue; stimulates cell proliferation; reduces cytokines and matrix metalloproteinases; reduces bacterial load; draws wound edges together. Effect of disinfection and sterilization of ozone can occur in an instant, and use widely in clinical experience, such as air disinfection, uterine infections treatment, dental infections treatment, etc. But because of toxic effects of ozone in human, especially respiratory toxin when exposed repeatedly, closure system should be developed in order to avoid toxic effects. Professor CAI Jinfang propose innovative concept of ozone negative pressure wound therapy (ONPWT):NPWT can be short-term alternative to soft tissue's coverage; be isolated from air; reduce opportunities for cross-infection; accelerate shedding of necrotic tissue of infection wound; reduce secretions; effective control of infection; promote growth of granulation and wound healing. At the same time, ozone can be used as a fungicide to kill harmful micro-organisms to prevent wound infections; improve wound oxygen pressure and promote wound healing. Ozone has strong oxidizing and corrosive effect, and almost has a corrosive effect on all metals, in addition to gold and platinum. Foam and semipermeable membrane also can be eroded. So we have to select anti-ozone oxidation and histocompatibility good material, used to design ONPWT.Purpose:To studies ozone oxidant Effect on medical foam and semipermeable membrane, in order to find appropriate antioxidant foam and membrane.Methods:the study included three parts.Part I:Selected medical PU foam (Shanghai Ying Lang Science&Technology Co., Ltd.) and medical PVA foam (Wuhan VSD Medical Science&Technology Co., Ltd.). Establishment of ozone water rinse vacuum model in vitro:placing foam on the glass, indwelling rinse tube and suction tube on both sides, sealing and fixing foam on the glass by using semipermeable membrane, connecting rinse tube to ozone water generator, connecting suction tube to suction device, irrigation through rinse tube using different concentrations of ozone water at 5min,20min, and 40min. And then we tested physical properties of foam before and after irrigation according to GB/T 6344-2008 standard, using WDW-10 electronic universal testing machine (including the maximum load of the drawing process, the instantaneous distance when sample torn), and tested the chemical structure of foam before and after irrigation using of laser Raman spectroscopy.Partâ…¡:Selected semipermeable membrane (Smith&nephew). Establishment of ozone water rinse vacuum model in vitro:placing foam on the glass, indwelling rinse tube and suction tube on both sides, sealing and fixing foam on the glass by using semipermeable membrane, connecting rinse tube to ozone water generator, connecting suction tube to suction device, irrigation through rinse tube using different concentrations of ozone water at different time. And then we tested physical properties of semipermeable membrane before and after irrigation according to GB/T 16578-1996 standard, using WDW-10 electronic universal testing machine, and tested the chemical structure of semipermeable membrane before and after irrigation using of laser Raman spectroscopy.Partâ…¢:Establishment of ozone water rinse vacuum model in vitro, irrigation with 4mg/L ozone water, sucking out the ozone water after 5min, 10min, and 15min, and measuring the concentration of it.Results:Part I:Part I:When using 4mg/L of ozone water rinse 20min or 10mg/L rinse 5min, the physical properties of PU foam medical unchanged. When 4mg/L rinse 40min; 10mg/L rinse 20min; 30mg/L rinse 5min, the physical properties of PVA foam(including the maximum load of the drawing process, the instantaneous distance when sample torn) has not changed. Laser Raman spectroscopy of two kinds of foam before and after irrigation showed that their chemical structures were not changed.Part II:according to GB/T 16578-1996 standard, load-displacement curve of semipermeable membrane had no significant changes. Laser Raman spectroscopy of membrane before and after irrigation showed that chemical structures were not changed.Part III:ozone water concentration will be reduced accordingly in ONPWT systems, which however still has bactericidal ability.Conclusions:Medical polyurethane foam, polyvinyl alcohol foam, as well as medical semi-permeable membrane can endure oxidant effect of ozone, which can be applied to ONPWT. The performance of PVA foam is better than PU foam. Tear resistance was not changed before and after irrigation. However, with the irrigation time extending, porous aperture of semi-permeable membrane increases, which reduce its function of isolating bacteria from the outside.
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