Miniature implantable laser Doppler probe monitoring of free tissue transfer

A 2.5-mm fiber-optic laser Doppler flowmetry probe has been applied in an experimental dog model as well as in 5 clinical cases to provide continuous readout of deep tissue perfusion. The rectus abdominis muscle in the dog was used for the experimental verification of the probe, which has a linear correlation with flow rate and a rapid response (6 seconds) to arterial occlusion and venous occlusion (20 seconds). Four of the 5 free tissue transfers survived with the laser Doppler instrument correctly identifying the lack of flow, both intraoperatively and postoperatively, in the failed flap. This probe greatly extends the versatility of laser Doppler flow measurement in the clinical setting and may be nearly an ideal probe for monitoring free tissue transfer, particularly muscle.