Laser speckle contrast imaging accurately measures blood flow over moving skin surfaces

Cutaneous blood flow (CBF) can be assessed non-invasively with lasers. Unfortunately, movement artefacts in the laser skin signal (LS_sk) might sometimes compromise the interpretation of the data. To date, no method is available to remove movement artefacts point-by-point. Using a laser speckle contrast imager, we simultaneously recorded LS_sk and the signal backscattered from an adjacent opaque surface (LS_os). The completion of a first protocol allowed a definition of a simple equation to calculate the CBF from movement artefact-affected traces of LS_sk and LS_os. We then recorded LS_sk and LS_os before, during and for 5 min after the tourniquet ischemia, both when subjects (n = 8) were immobile or submitted to external passive movements of random intensity throughout the test. The typical post-occlusive reactive hyperemia trace was not identifiable within the LS_sk recordings, with LS_sk being 2 to 3 times higher during movements than in the immobile situation. After the calculation of CBF, traces in the immobile versus movement conditions were comparable, with the “r” cross-correlation coefficient being 0.930+/−0.010. Our method might facilitate future investigations in microvascular physiology and pathophysiology, specifically in subjects who have frequent or continuous involuntary movements.