Red blood cell velocity and volumetric flow assessment by enhanced high-resolution laser Doppler imaging in separate vessels of the hamster cheek pouch microcirculation

An enhanced high-resolution laser Doppler imager (EHR-LDI), configured to f it the demands of a measurement area containing separate microvessels, was evaluated for perfusion measurements in hamster cheek pouch preparations du ring ischemia, reperfusion, and pharmacologically induced vasodilation and vasoconstriction. Measurements in separate microvessels where the laser bea m was smaller than the vessel diameter were referred to as red blood cell ( RBC) velocity estimates, as previously validated in vitro, whereas a relati ve how index, RFI (mean RBC velocity/tissue area), was introduced as a volu metric dow measure. Microvessel diameter and RBC velocity changes during is chemia, reperfusion, as well as during vasoconstriction and vasodilation co rrelated to the data obtained from the microscope. Correspondingly, during the described provocations anticipated volumetric dow changes were register ed as changes in the RFI. When data on intravessel RBC velocity profiles ar e presented they reflect a parabolic flow profile usually seen in this size microvessel. The EHR-LDI appears a promising tool for investigation of the microvasculature, as it almost simultaneously provides information on rela tive changes of both in vivo RBC velocity and volumetric flow (RFI), althou gh the latter estimate needs to be further refined. (C) 1999 Academic Press .