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Real-time Assessment Of Capillary Circulation Of Free Flap Using Video-capillaroscopy: A Technological Renaissance?
Arbab Mohammad, MBBS1, Joseph M. Escandón, MD2, Daniela Duarte Bateman, MD3, Oscar J. Manrique, MD, FACS2, Eba Baig, MBBS1, Chihiro Matsui, MD4, Takakuni Tanaka, MD5, Yoshie Toyota, MD6.
1Aarupadai Veedu Medical College and Hospital, Puducherry, India, 2University of Rochester Medical Center, Rochester, NY, USA, 3Cleveland Clinic Lerner Research Institute, Cleveland, OH, USA, 4Juntendo University School of Medicine, Tokyo, Japan, 5Toyooka Hospital, Hyogo, Japan, 6Okinawa central hospital, Okinawa, Japan.

PURPOSE: Many clinical assessment methods including flap color monitoring and capillary refill time are commonly used to assess the microcirculation of the flap; yet there is no objective tool available that can clearly visualize in real-time flap microcirculation. The purpose of this study was to use video-capillaroscopy (VC) to evaluate the circulation changes on free flap skin surfaces while purposely clamping pedicle vessels.
METHODS: Ten free flaps for reconstruction of head and neck defects were used. All flaps were elevated with room temperatures between 22-25°C. VC (Bscan-Z, No.EV-80Z, GOKO Imaging Devices Co., Ltd., Japan) enabled the observation of tissue with a depth of about 1-mm from the skin surface. Measurements of the visual field were performed with ImageJ analysis software. The size of the camera field was 0.35 mm2/point (Observed with a zoom about 145x to 590x). We measured the total blood vessel area (pixels) as a percentage of the total area of the visual field (pixels). Changes in blood flow velocity were measured using GOKO-VIP Software (GOKO-Imaging Devices Co.Ltd.,Japan). The main perforator was located at least 1cm towards the proximal point from the center line. One proximal and one distal observation point were defined for each flap, each 1cm from the border of the flap. We observed the flap skin condition in situ with VC before transection of the pedicle. The area of capillary density (capillary number/0.35mm2) and average blood flow velocity (μm/s) were measured for 10 seconds. Then, to simulate flap ischemia and flap congestion, we observed the flap skin capillary changes in each of the four situations: Normal condition to arterial clamping (NC-AC), Arterial declamping to normal condition (AC-NC), Normal condition to venous clamping (NC-VC), and Venous declamping to normal condition (VC-NC).
RESULTS: Two chimeric scapular flaps, six anterolateral thigh flaps, and two rectus abdominis flaps were included. The clamp experiment did not affect the circulation of the flap after anastomosis. There were no cases of postoperative flap loss or vascular occlusion. The average blood flow was slower at the distal versus the distal point, both before and after vascular anastomosis. Within 1 minute during NC-AC, the entire flap exhibited minimal presence of red blood cells. During AC-NC, the blood vessels showed immediate vasodilation. During NC-VC, the distal point of the flap showed a significantly higher vasodilation rate at 30-sec (11.9% versus 11.1%) and 60-sec (16.1% versus 13.5%) after clamping (p <0.05). During VC-NC, capillary congestion immediately disappeared after declamping followed by a decrease in vasodilation rate. The movement of red blood cells stopped in most blood vessels after 60 seconds of clamping. During both AC-NC and VC-NC, the change in blood flow velocity (μm/s) was faster in the proximal point than the distal point at 60 seconds (p <0.001).
CONCLUSION: Video-capillaroscopy can be utilized for objective real-time flap monitoring by directly visualizing flap skin capillary microcirculation.


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