title: Perfusion dynamics in lower limb reconstruction: Investigating postoperative recovery and training using combined white light photospectroscopy and laser Doppler (O2C(®)).
abstract: BACKGROUND
  Postoperative regimes designed to acclimatise lower limb free flaps to the changing flow dynamics of standing (flap training exercises) are widely employed despite a paucity of evidence for their use. This study utilises non-invasive monitoring of perfusion parameters to investigate flap training at the microcirculatory level.
  
  
  METHODS
  Eight prospective patients undergoing lower limb reconstruction with anterolateral thigh fasciocutaneous free flaps were enrolled. Combined tissue photospectroscopy and laser Doppler (O2C, LEA, Germany) was used to assess perfusion during five days of postoperative limb elevation and a subsequent three day flap training regime. Superficial Oxygen saturation (SO2), Haemoglobin concentration (rHb) and Flow measurements were taken. Readings were compared to pre-training control measurements.
  
  
  RESULTS
  In the first five postoperative days of limb elevation, there were no significant changes in perfusion parameters. On commencement of flap training, 5 min of leg dependency resulted in mean decreases in SO2 of 45% on day 1 (p = 0.05) and 56% on day 2 (p = 0.02). Haemoglobin concentrations increased by 20% on day 1 (p = 0.01) and 26% on day 2 (p = 0.02). Flow decreased by 67% on day 1 (p = 0.19) and 78% day 2 (p = 0.03). On day 3 changes were observed to a lesser degree and only rHb increases remained statistically significant (p = 0.01).
  
  
  CONCLUSIONS
  Prior to flap training, lower limb dependency causes reduced oxygenation, increased venous pooling and decreased flow consistent with venous congestion. Following a three day training regime, flap perfusion begins to accommodate for these changes. These findings provide a rationale for flap training, although further work is required to explain the mechanisms.
authors.affiliation: Imperial College Healthcare NHS Trust, London, England, United Kingdom.
authors.forename: John M D
authors.initials: JM
authors.lastname: Henton
authors.affiliation: Imperial College Healthcare NHS Trust, London, England, United Kingdom.
authors.forename: Jonathan M H
authors.initials: JM
authors.lastname: Simmons
authors.affiliation: Imperial College Healthcare NHS Trust, London, England, United Kingdom.
authors.forename: Shehan
authors.initials: S
authors.lastname: Hettiaratchy
authors.affiliation: Imperial College Healthcare NHS Trust, London, England, United Kingdom; Kennedy Institute of Rheumatology, University of Oxford, Oxford, England, United Kingdom. Electronic address: abhilash.jain@kennedy.ox.ac.uk.
authors.forename: Abhilash
authors.initials: A
authors.lastname: Jain
mesh_terms: D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology; D015331:Cohort Studies; D005500:Follow-Up Studies; D005592:Fracture Fixation / Q000379:methods; D005597:Fractures, Open / Q000000981:diagnostic imaging / Q000601:surgery; D005858:Germany; D006085:Graft Survival; D006801:Humans; D017078:Laser-Doppler Flowmetry; D007869:Leg Injuries / Q000175:diagnosis / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D010100:Oxygen / Q000097:blood; D011859:Radiography; D019651:Plastic Surgery Procedures / Q000379:methods*; D012039:Regional Blood Flow / Q000502:physiology*; D012189:Retrospective Studies; D018570:Risk Assessment; D013053:Spectrophotometry; D013524:Surgical Flaps / Q000098:blood supply* / Q000637:transplantation; D013978:Tibial Fractures / Q000000981:diagnostic imaging / Q000601:surgery; D014945:Wound Healing / Q000502:physiology; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: Flap perfusion; Flap training; Laser Doppler; Lower limb reconstruction; Open tibial fracture; Tissue photospectroscopy