Measurement of cerebral blood flow and oxygen saturation using laser Doppler flowmetry anal near infrared spectroscopy in ischemic stroke rats

Near infrared spectroscopy (NIRS) has been recently developed as a noninvasive technique to assess cerebral oxygenation, hemodynamics and neuronal activity in animals and humans. In the present study, we applied laser Doppler flowmetry (LDF) and NIRS to compare the changes in cerebral blood flow (CBF) with changes of NIRS parameters including concentrations of de/oxygenated hemoglobin (Hb and HbO₂), total hemoglobin (HbT) and cerebral oxygen saturation (StO₂) in rats subject to transient (60-mins) middle cerebral artery occlusion (MCAO). In addition, NIRS parameters were recorded from the initial ischemic events up to the fourth day after permanent ischemia. Ischemic changes, averaged over the 60 minutes of occlusion, were as follows: ΔCBF = -54.58 ± 6.38%, ΔStO₂ = -14.49 ± 2.82%, ΔHbT = -11.66 ± 10.23 μM, ΔHbO₂ = -28.47 ± 9.10 μM, ΔHb = 16.82 ± 4.63 μM. Our results revealed good correlation between the changes in laser Doppler flow and StO₂. Mismatch between cerebral blood flow and volume was also found. The results of time course monitoring in rats with permanent MCAO showed that the changes in [HbO₂] and in StO₂ were similar to the behavioral recovery. Our study suggested that NIRS might be a practical tool for noninvasive and continuous monitoring of the hemodynamic condition of ischemic stroke during recovery or for therapeutic schemes.