title: Ischaemic time and fat necrosis in breast reconstruction with a free deep inferior epigastric perforator flap.
abstract: OBJECTIVE
  Fat tissue can be injured by ischaemia in free flap surgeries, leading to the development of fat necrosis. The aim of this study was to evaluate the association between ischaemic time and fat necrosis in microsurgical breast reconstruction using a deep inferior epigastric perforator (DIEP) flap.
  
  
  METHODS
  A retrospective chart review was performed for patients who underwent breast reconstruction with free DIEP flaps between June 2009 and November 2011. Data regarding patient demographics, potential risk factors and fat necrosis were collected. Fat necrosis was diagnosed with ultrasound imaging between 3 and 6 months postoperatively. Univariate and multivariate analyses were used to assess the correlation between ischaemic time and fat necrosis rate. Receiver operating characteristic curve analysis was used to determine a cut-off value for the ischaemic time at which differential fat necrosis rates were maximal.
  
  
  RESULTS
  A total of 86 patients were included in this study. The mean ischaemic time was 89 min, and fat necrosis was diagnosed in 15 patients (17.4%). A significant association was found between ischaemic time and fat necrosis rate on univariate (p-value=0.001) and multivariate analyses (p-value=0.017). The trend analysis of ischaemic time as a categorical variable relative to fat necrosis rate was also significant (p-value<0.001). A threshold value was found whereby patients with an ischaemic time longer than 99.5 min appeared to experience a significantly higher fat necrosis rate than patients with shorter times (p-value=0.005, odds ratio=9.449).
  
  
  CONCLUSIONS
  Ischaemic time appears to be significantly associated with increased fat necrosis rate in breast reconstruction using DIEP flaps. A long ischaemia time may be a risk factor for the development of fat necrosis.
authors.affiliation: Department of Plastic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Irwon-dong 50, Gangnam-gu, Seoul 135-710, South Korea.
authors.forename: Kyeong-Tae
authors.initials: KT
authors.lastname: Lee
authors.forename: Jeong Eon
authors.initials: JE
authors.lastname: Lee
authors.forename: Seok Jin
authors.initials: SJ
authors.lastname: Nam
authors.forename: Goo-Hyun
authors.initials: GH
authors.lastname: Mun
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001943:Breast Neoplasms / Q000473:pathology / Q000601:surgery; D015331:Cohort Studies; D050377:Cold Ischemia / Q000009:adverse effects*; D019074:Epigastric Arteries / Q000601:surgery; D005218:Fat Necrosis / Q000209:etiology* / Q000503:physiopathology; D005260:Female; D005500:Follow-Up Studies; D006084:Graft Rejection; D006085:Graft Survival; D006801:Humans; D007431:Intraoperative Complications / Q000503:physiopathology; D016462:Mammaplasty / Q000009:adverse effects* / Q000379:methods; D008408:Mastectomy / Q000379:methods; D008866:Microsurgery / Q000009:adverse effects / Q000379:methods; D008875:Middle Aged; D015999:Multivariate Analysis; D061525:Perforator Flap / Q000098:blood supply*; D012372:ROC Curve; D017568:Rectus Abdominis / Q000098:blood supply / Q000637:transplantation*; D012189:Retrospective Studies; D016896:Treatment Outcome; D014945:Wound Healing / Q000502:physiology