With novel model-based analysis algorithms, it is now possible to measure the tissue blood perfusion in absolute units divided into different speeds, i.e. tissue fraction of red blood cells (RBC) multiplied with speed – % RBC × mm/s – divided in blood flowing with speed below 1 mm/s, 1-10 mm/s, and above 10 mm/s. Compared to conventional perfusion, measured in perfusion units PU, the speed resolved perfusion facilitates discrimination between different flow compartments, for example nutritive flow from shunt flow.
By combining measurements of tissue oxygen saturation and speed resolved perfusion, a comprehensive view of the microcirculation and the tissue metabolism can be achieved. We offer the PeriFlux 6000 EPOS instrument to measure these microvascular parameters in the same sampling volume using an integrated fiber-optic probe and advanced model-based signal analysis. The parameters from the EPOS are:
Oxygenized and reduced hemoglobin tissue concentration (µM)
Speed-resolved perfusion: gram RBC / 100 gram tissue × mm/seconds (% RBC × mm/second). Three different speed regions: < 1 mm/second, 1 to 10 mm/second, and > 10 mm/second
Measurement depth (mm)
Various provocations protocols, such as local heating or brachial occlusion, are preferably used in combination with these microcircular measurements, in order to reveal more information about the microvascular function. There is built-in automatic support for those provocations in the EPOS instrument.
Figure caption: 15 second speed-resolved perfusion recording on fingertip.