title: Advanced Microcirculatory Parameters of Lower Extremity Free Flaps during Dangling and Their Influencing Factors.
abstract: BACKGROUND
  Dangling of the leg to habituate a free flap to the lower extremity is common practice. However, little is known about the microcirculatory changes in free flaps and the influence of comorbidities.
  
  
  METHODS
  Tissue oxygen saturation (StO2) and hemoglobin content (tissue hemoglobin index [THI]) of 39 lower extremity free flaps was measured during dangling on postoperative days (PODs) 6 to 9. We assessed the maximal desaturation during dangling and re-elevation and the maximal increase in THI as well as the time required to reach a stable plateau during dangling, among others.
  
  
  RESULTS
  All parameters showed significant changes during dangling (desaturation during dangling: 0.23 ± 10.7 vs. - 4.66 ± 12.6%, p = 0.001 for POD 6 vs. 7; further desaturation after re-elevation: - 11.1 ± 7.4 versus - 14.5 ± 7.8%, p = 0.001 for POD 6 vs. 9; THI increase during dangling: from 3.4 ± 1.6 to 4.2 ± 1.8 AU, p = 0.008, time to THI plateau: 1.7 ± 1.2 vs. 2.5 ± 1.7 minutes, p = 0.004 for POD 6 vs. 7). Age, gender, and smoking did not influence the mentioned parameters. Nondiabetic patients showed a significant increase of baseline StO2, whereas diabetic patients did not (p = 0.009 vs. 0.11). For THI, both diabetic and hypertensive patients showed a lower increase in THI on the first day of dangling (p = 0.056; p = 0.009) and significantly lower baseline values on the last day (0.046 for both).
  
  
  CONCLUSIONS
  Duration of dependency seems to have the greatest impact on microcirculation during dangling, although comorbidities may interfere with the adaptive processes. An earlier start of dangling could safely be applied in most patients. Special care needs to be taken in diabetic and hypertensive patients.
authors.affiliation: Department of Plastic Surgery, Burn Center, Sarcoma Center, BG University Hospital, Ruhr University, Bochum, Germany.
authors.forename: Jonas
authors.initials: J
authors.lastname: Kolbenschlag
authors.affiliation: Department of Plastic Surgery, Burn Center, Sarcoma Center, BG University Hospital, Ruhr University, Bochum, Germany.
authors.forename: Pascal
authors.initials: P
authors.lastname: Bredenbroeker
authors.affiliation: Department of Plastic Surgery, Burn Center, Sarcoma Center, BG University Hospital, Ruhr University, Bochum, Germany.
authors.forename: Marcus
authors.initials: M
authors.lastname: Lehnhardt
authors.affiliation: Department of Plastic Surgery, Burn Center, Sarcoma Center, BG University Hospital, Ruhr University, Bochum, Germany.
authors.forename: Adrien
authors.initials: A
authors.lastname: Daigeler
authors.affiliation: Department of Hand, Plastic and Reconstructive Surgery, Burn Trauma Center, BG Trauma Center Ludwigshafen, University of Heidelberg, Ludwigshafen, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Fischer
authors.affiliation: Department of Plastic Surgery, Burn Center, Sarcoma Center, BG University Hospital, Ruhr University, Bochum, Germany.
authors.forename: Kamran
authors.initials: K
authors.lastname: Harati
authors.affiliation: Department of Plastic Surgery, Burn Center, Sarcoma Center, BG University Hospital, Ruhr University, Bochum, Germany.
authors.forename: Andrej
authors.initials: A
authors.lastname: Ring
authors.affiliation: Department of Plastic Surgery, Burn Center, Sarcoma Center, BG University Hospital, Ruhr University, Bochum, Germany.
authors.forename: Ole
authors.initials: O
authors.lastname: Goertz
mesh_terms: D015897:Comorbidity; D005260:Female; D058752:Free Tissue Flaps / Q000098:blood supply*; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D035002:Lower Extremity / Q000098:blood supply*; D008297:Male; D008833:Microcirculation / Q000502:physiology*; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D056888:Patient Positioning; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology
chemical_list: D006454:Hemoglobins; D010100:Oxygen