Letter to the Editor regarding: Negative pressure wound therapy Re: Wang X, Zhang Y, Han C: Topical negative pressure improves autograft take by altering nutrient diffusion: A hypothesis.
I read the article of Wang et al. [1] entitled "Topical negative pressure improves autograft take by altering nutrient diffu sion: A hypothesis" with great interest. Negative pressure wound therapy (NPWT) is generally used in a two step surgi cal procedure to treat surgical site infections. At the time the wound is sterile and wound granulation has been initiated, the wound can be secondary surgically closed using different available techniques, such as direct sternal closure, pectora lis muscle flap, rectal muscle flap, omentum plasty or latissi mus dorsi plasty.Today, NPWT is also used to prevent surgical site infections after surgery, due to the unique positive applied mechanical forces as a permutation of Wolff's law. Additionally it is also used to support more superficial full thickness skin defects where mobilization of the surrounding tissue is not possible or limited and extensions are needed by different substitutes. The current study is important in patients who are treated for acute full thickness skin defects with this hypothesized one step closure method, using a commercial dermal substitute. The authors report that it takes approximately three weeks for these substitutes to become completely vascularized. Up till this time period, the functionality of the material is not com parable with native skin tissue, which forms a natural barri er against microbial invasion. The hypothesis of the authors was concentrated only on rapid balance of nutrient supply and angiogenesis due to NPWT, but by reading the literature care fully, NPWT seems to be even more innovative [2].Previous studies have shown that NPWT can significantly de crease the tissue bacterial count as early as four days after implementing this therapy compared with controls in a ran domized trial. Therefore NPWT is not only an active barrier for microbes to enter the skin, but also the number of microbes is actively reduced after starting this therapy. Furthermore the sub atmospheric pressure will prevent the progressive tissue damage of the surrounding tissue at the initial injury, start ing hours after insertion. Additionally wound oedema is re duced, as well as proteolytic enzymes and cytokines deriving from cell necrosis will be transported away from the granu lation tissue, which will improve wound healing. On the oth er hand it is also conceivable that supporting mediators for wound healing are transported away from the wound by in stalling NPWT. Further studies will be needed to identify and analyse these factors and evaluate potential possibilities to administer these mediators to the patients or better synthe tises them and apply them locally.It would be desirable to receive more experimental and clini cal data on this one step procedure, to better understand all single supportive developments to improved results of dermal substitutes to close theses full thickness skin defects.