Prompt, Objective, and Accurate Measurement of Rat Abdominal Flap Blood Flow Using Laser Speckle Flowgraphy

The indications for free flap procedures have expanded, with recent technical advances enhancing procedural safety. However, few objective indicators exist to monitor flap status during and after the operation. This experimental study assessed laser speckle flowgraphy (LSFG) as a prompt and accurate indicator of free flap blood flow. After elevating bilateral lower abdomen flaps with superficial inferior epigastric artery (SIEA) and superficial inferior epigastric vein vasculature in Wistar rats, the right flap with the SIEA was cut (ischemic group) or the superficial inferior epigastric vein was cut (congestive group), and the unaltered left flaps were monitored using LSFG every 5 minutes for a 30-minute period. Flap survival or necrosis was assessed after 7 days. In the ischemic group, LSFG measurements were significantly lower after cutting the SIEA than beforehand (74% at 5 minutes and 72% at 30 minutes). Similar findings were seen in the congestive group (63% at 5 minutes and 55% at 30 minutes). LSFG measurements were significantly lower in the congestive group than in the ischemic group. Seven days afterward, whereas all right-side flaps with cut vessels were necrotic, all unaltered left-side flaps had survived. Our preliminary results demonstrated that LSFG could objectively identify abnormal blood flow in skin flaps as early as 5 minutes into surgery and predict graft survival. LSFG may potentially enable quick and objective assessment of flap blood flow and reduce the risk of complications and flap loss.