An alternative index for monitoring microcirculatory blood flow: The beat-to-beat microcirculatory blood flow variability

Objective: Cardiovascular variability analysis, such heart rate variability or blood pressure variability, provides important information about activities of various regulatory mechanisms for the cardiovascular system. Aim of the present study is to use the laser Doppler flowmetry (LDF) measurement to study the correspondent changes between the beat-to-beat microcirculatory blood flow (MBF) and its variation (MBFV). Methods: 17 trials were performed on 5 male healthy volunteers. For each experiment, we applied local heating (LH) stimulation and recorded a 20-minute heating-effect data sequence. For each pulse, DCflux (average LDF flux) was calculated, and CV (coefficient of variation) of DCflux (DCCV) was then calculated to evaluate the beat-to-beat MBFV. Results: The slope between DCCV and DCflux was negative with R² >0.7 (p<0.01 by F-test). Conclusion: Our results suggest that by providing an alternative solution to overcome the major drawback for LDF measurement of lacking quantitative evaluation, MBFV parameters calculated from the beat-to-beat LDF waveform may have meaning in improving the evaluation for the LH response of the MBF perfusion.