Impact of active thermoregulation on the microcirculation of free flaps.
BACKGROUND
While it is a known fact that warming increases blood flow in healthy tissue, little is known about the impact of active thermoregulation on the altered microcirculation of free flaps. The objective of the study was to identify the impact of postoperative active thermoregulation on free flap microcirculation.


METHODS
Tissue temperature was assessed in 25 free perforator flaps using an implanted probe. Active thermoregulation was achieved using a water circulation based system. Changes in microcirculation were evaluated at the day of surgery and throughout the first three postoperative days after passive cooling (room temperature), passive warming (wound dressing), active warming (38 °C) and active cooling (15 °C) using laser Doppler flowmetry and remission spectroscopy.


RESULTS
Active warming increased flap temperature by 7.7% to 36.4 °C ± 0.5 °C in comparison to the initial values of flaps without dressing (P < 0.001). As a result, the blood flow increased by 77.7% of the base value (P < 0.001). A significant correlation between all microcirculation parameters and tissue temperature was observed with a 5.52 AU blood flow increase per degree temperature increase (r = 0.7; P < 0.001). All microcirculation parameters showed a statistically significant increase after both passive and active warming, whereby active warming showed significantly higher values than passive warming.


CONCLUSIONS
Active thermoregulation using water-based circulation is an effective and safe procedure to improve microcirculation in free flaps and is superior to conventional passive warming strategies.
Department of Plastic, Reconstructive, Hand and Burn Surgery, Bogenhausen Academic Hospital, Technische Universität München, Munich, 81925, Germany.
Ulf
U
Dornseifer
Department of Oral and Maxillofacial Surgery, Technische Universität München, Klinikum rechts der Isar, Munich, 81675, Germany.
Andreas Max
AM
Fichter
Department of Plastic, Reconstructive, Hand and Burn Surgery, Bogenhausen Academic Hospital, Technische Universität München, Munich, 81925, Germany.
Sarah
S
Von Isenburg
Department of Plastic, Reconstructive, Hand and Burn Surgery, Bogenhausen Academic Hospital, Technische Universität München, Munich, 81925, Germany.
Sofia
S
Stergioula
Institute of Medical Statistics and Epidemiology, Technische Universität München, Munich, 81675, Germany.
Ina-Christine
IC
Rondak
Department of Plastic, Reconstructive, Hand and Burn Surgery, Bogenhausen Academic Hospital, Technische Universität München, Munich, 81925, Germany.
Milomir
M
Ninkovic
D000293:Adolescent; D000328:Adult; D001831:Body Temperature; D001833:Body Temperature Regulation / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D058752:Free Tissue Flaps / Q000098:blood supply* / Q000502:physiology; D006358:Hot Temperature / Q000627:therapeutic use*; D006801:Humans; D006875:Hydrotherapy / Q000379:methods*; D017078:Laser-Doppler Flowmetry; D008297:Male; D008833:Microcirculation / Q000502:physiology*; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D011182:Postoperative Care / Q000379:methods*; D011446:Prospective Studies; D019651:Plastic Surgery Procedures; D055815:Young Adult