title: Negative pressure wound therapy reduces the ischaemia/reperfusion-associated inflammatory response in free muscle flaps.
abstract: BACKGROUND
  We recently established negative pressure wound therapy (NPWT) as a safe postoperative care concept for free muscle flaps; however, the molecular effects of NPWT on free muscle flaps remain elusive. Here we investigated the effects of NPWT on pathological changes associated with ischaemia/reperfusion injury in free flap tissue.
  
  
  METHODS
  From July 2008 to September 2010, 30 patients receiving skin-grafted free muscle transfer for defect coverage were randomly assigned to two treatment groups: In one group the skin-grafted free flap was covered by a vacuum dressing (NPWT); in the second group, flaps were covered by conventional petroleum gauze dressings (conv). Biopsies were taken intra-operatively prior to clipping of the pedicle and on postoperative day 5. Samples were analysed by immunohistochemistry for infiltration of inflammatory cells, real-time polymerase chain reaction (RT-PCR) for the analysis of expression levels of interleukin-1β (IL-1β) and tumour necrosis factor (TNF)-alpha as markers of inflammation. Histological samples were also examined for interstitial oedema formation, and apoptosis was detected by a terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) assay.
  
  
  RESULTS
  NPWT leads to a significantly reduced tissue infiltration of CD68 + macrophages and reduced expression of the inflammatory cytokines IL-1β and TNFα. None of these parameters was significantly elevated in the pre-ischaemic biopsies. Furthermore, NPWT reduced the interstitial oedema formation and the number of apoptotic cells in free flap tissue.
  
  
  CONCLUSIONS
  NPWT of skin-grafted free muscle flaps leads to a reduced inflammatory response following ischaemia/reperfusion, resulting in reduced oedema formation improving the microcirculation and ultimately reduced tissue damage. We thereby deliver new insight into the effects of NPWT.
authors.affiliation: Department of Plastic and Hand Surgery, University of Freiburg Medical Centre, Hugstetter Strasse 55, 79106 Freiburg, Germany. steffen.eisenhardt@uniklinik-freiburg.de
authors.forename: S U
authors.initials: SU
authors.lastname: Eisenhardt
authors.forename: Y
authors.initials: Y
authors.lastname: Schmidt
authors.forename: J R
authors.initials: JR
authors.lastname: Thiele
authors.forename: N
authors.initials: N
authors.lastname: Iblher
authors.forename: V
authors.initials: V
authors.lastname: Penna
authors.forename: N
authors.initials: N
authors.lastname: Torio-Padron
authors.forename: G B
authors.initials: GB
authors.lastname: Stark
authors.forename: H
authors.initials: H
authors.lastname: Bannasch
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis; D001458:Bandages; D001706:Biopsy; D004487:Edema / Q000378:metabolism / Q000628:therapy; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D053583:Interleukin-1beta / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000637:transplantation*; D054843:Negative-Pressure Wound Therapy; D010577:Petrolatum; D060888:Real-Time Polymerase Chain Reaction; D015427:Reperfusion Injury / Q000378:metabolism / Q000628:therapy*; D016038:Skin Transplantation / Q000379:methods*; D013524:Surgical Flaps; D016896:Treatment Outcome; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D053583:Interleukin-1beta; D014409:Tumor Necrosis Factor-alpha; D010577:Petrolatum