Laser Speckle Contrast Imaging is a Promising Tool for Monitoring of Partial and Full Venous Outflow Obstruction - An Experimental Study in a Porcine Flap Model
Johan Zötterman, MD PhD, Fredrik Iredahl, MD PhD, Max Bergkvist, MD PhD, Erik Tesselaar, PhD, Simon Farnebo, MD PhD.
Linkoping University, Linkoping, Sweden.
In microsurgery, there is a demand for more reliable methods for flap monitoring. We used laser speckle contrast imaging and laser Doppler flowmetry to assess partial and full venous outflow obstruction in a porcine flap model.
Cranial gluteal artery perforator flaps were raised and arterial and venous blood flow 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. The flap microcirculation was monitored using Laser Speckle Contrast Imaging (LSCI) and Laser Doppler Flowmetry (LDF).
After partial (50%) venous occlusion, perfusion decreased from baseline (LSCI: p = 0.007, LDF: p = 0.07). After 100% venous occlusion, a further decrease in perfusion was observed (LSCI: p = 0.01, LDF: p = 0.05). After release of the venous cuff, LSCI detected a return of the perfusion to a level slightly below baseline level (p = 0.001) while the LDF signal returned to a level not significant from baseline (p = 0.99). During 50% and 100% venous occlusion, LSCI showed a 20% and 26% intersubject variability (CV %), respectively, compared to 50% and 77% for LDF.
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 large area of flap tissue. This may be useful in identifying areas of the flap with compromised microcirculation during and after surgery.
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