Monitoring of Partial and Full Venous Outflow Obstruction in a Porcine Flap Model using Laser Speckle Contrast Imaging

• Published in: Journal of plastic, reconstructive & aesthetic surgery Vol. 69; no. 7; pp. 936 - 943
• Main Authors: Zötterman, Johan, Bergkvist, Max, Iredahl, Fredrik, Tesselaar, Erik, Farnebo, Simon
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 01-07-2016
• Subjects: Animals; Arterial occlusion; Arterial Occlusive Diseases - diagnosis; Arterial Occlusive Diseases - physiopathology; Arteries - diagnostic imaging; Arteries - physiopathology; Blood Flow Velocity; Free flaps; Free Tissue Flaps - adverse effects; Free Tissue Flaps - blood supply; Hemodynamics; Laser Doppler; Laser speckle contrast imaging; Laser-Doppler Flowmetry - methods; Microsurgery - adverse effects; Microsurgery - methods; Models, Anatomic; Plastic Surgery; Postoperative Complications - diagnosis; Postoperative Complications - physiopathology; Postoperative Complications - prevention & control; Reconstructive Surgical Procedures - adverse effects; Reconstructive Surgical Procedures - methods; Regional Blood Flow; Reproducibility of Results; Swine; Vascular Patency; Veins - diagnostic imaging; Veins - physiopathology; Venous occlusion; laser speckle contrast imaging; free flaps; laser Doppler; arterial occlusion; venous occlusion; Laser Doppler; Laser speckle contrast imaging; Free flaps; Venous occlusion; Arterial occlusion
• ISSN: 1748-6815; 1878-0539; 1878-0539
• DOI: 10.1016/j.bjps.2016.02.015

Abstract Background In microsurgery, there is a demand for more reliable methods of postoperative monitoring of free flaps, especially with regard to tissue threatening obstructions of the feeding arteries and draining veins. In this study, we evaluated laser speckle contrast imaging and laser Doppler flowmetry to assess their possibilities to detect partial and full venous outflow obstruction, as well as full arterial occlusion, in a porcine flap model. Methods Cranial gluteal artery perforator flaps (CGAP) were raised and arterial and venous blood flow to and from the flaps was monitored using ultrasonic flow probes. The venous flow was altered with an inflatable cuff to simulate partial and full (50% and 100%) venous obstruction and arterial flow was completely obstructed using clamps. The flap microcirculation was monitored using Laser Speckle Contrast Imaging (LSCI) and Laser Doppler Flowmetry (LDF). Results Both LDF and the LSCI detected significant changes in flap perfusion. After partial (50%) venous occlusion, perfusion decreased from baseline, LSCI: 63.5 ± 12.9 PU (p = 0.01), LDF 31.3 ± 15.7 (p = 0.64). After 100% venous occlusion, a further decrease in perfusion was observed: LSCI 54.6 ± 14.2 PU (p < 0.001) and LDF 16.7 ± 12.8 PU (p < 0.001). After release of the venous cuff, LSCI detected a return of the perfusion to a level slightly, but not significantly, below baseline level 70.1 ± 11.5 PU (p = 0.39) while the LDF signal returned to a level not significant from baseline 36.1 ± 17.9 PU (p > 0.99). Perfusion during 100% arterial occlusion decreased significantly as measured with both methods, LSCI: 48.3 ± 7.7 (PU, p < 0.001) and LDF: 8.5 ± 4.0 PU (p < 0.001). During 50% and 100% venous occlusion, LSCI showed a 20% and 26% intersubject variability (CV %), respectively, compared to 50% and 77% for LDF. Conclusions LSCI offers sensitive and reproducible measurements of flap microcirculation and seems more reliable in detecting decreases in blood perfusion caused by venous obstruction. Also, it allows for perfusion measurements in a relatively large area of flap tissue. This may be useful in identifying areas of the flap with compromised microcirculation during and after surgery.