Laser Doppler flowmetry of hepatic microcirculation during Pringle's maneuver: determination of spatial and temporal liver tissue perfusion heterogeneity.

BACKGROUND

Laser Doppler flowmetry (LDF) is frequently used for non-invasive microvascular perfusion measurements. The aim of the present study was to analyze liver blood flow heterogeneity in detail using LDF devices under normal and low-flow conditions.

MATERIALS AND

METHODS

In 5 anesthetized and laparotomized Suabian-Hall strain pigs, systemic hemodynamics and hepatic arterial/portal venous blood flow were constantly recorded. Hepatic microcirculation was assessed by 2 different LDF devices, analyzing microvascular flow and velocity before, during and after inducing a Pringle's maneuver for hepatic inflow occlusion. Offline data analysis comprised differentiation between the two LDF devices used as well as calculation of temporal and spatial heterogeneity of liver perfusion.

RESULTS

Pringle's maneuver induced complete inflow occlusion, confirmed by hepatic arterial/portal venous blood flow measurement. Laser Doppler signals showed a significant decrease during Pringle's maneuver. Spatial heterogeneity of flow and velocity increased more than temporal heterogeneity during Pringle's maneuver.

CONCLUSION

Both LDF devices proved suitable for assessing hepatic microvascular perfusion during normal perfusion and low-flow conditions. Reduced microvascular perfusion induces a significant increase in temporal and spatial perfusion heterogeneity. In particular, the pronounced spatial heterogeneity requires measurements at different places when assessing hepatic microcirculation by LDF during impaired perfusion conditions.