Differentiation between arterial and venous vessel occlusion by simultaneous measurement with laser Doppler flowmetry and photoplethysmography.

In abdominal cutaneous island flaps of rats (n = 16), either the artery or the vein was clamped, while flap perfusion was simultaneously monitored with laser Doppler flowmetry (LDF) and photoplethysmography (PPG) to identify the occluded vessel responsible for insufficient perfusion. The LDF signal decreased promptly after arterial clamping. After venous clamping, only a slow decrease was noted. The LDF amplitude differed statistically significantly between arterial and venous clamping only up to 90 sec after onset but not thereafter, allowing no further distinction between the two types of vessel occlusion. Power spectral analysis of the LDF signal did not show clear differences in frequency ranges between arterial and venous occlusion. In contrast, PPG measurements demonstrated significant differences between both perfusion disorders throughout the entire observation period. These results suggest that dependable differentiation between prolonged arterial and venous vessel occlusion is not possible based on the amplitude or power spectral analysis of the LDF signal alone. PPG may be reliably used to differentiate between arterial and venous perfusion disorders.