Wearable fiber-free optical sensor for continuous monitoring of cerebral blood flow (CBF) responses to intracranial pressure (ICP) elevations in rats (Conference Presentation)

We developed an innovative, wearable, fiber-free, diffuse speckle contrast flowmetry (DSCF) probe for continuous CBF monitoring in rats with gradiently elevated intracranial pressure (ICP). A miniaturized DSCF probe was glued to the left skull of an adult rat (4-5 months old) under 2% Isoflurane anesthesia. A commercial solid-state ICP sensor (iWorx RA Recorder) was inserted into the right lateral ventricle, through which saline was injected gradiently with increased speeds by a syringe pump. The gradient injection of saline resulted in gradient ICP elevations, leading to progressive reductions in CBF. Importantly, CBF and ICP variations are correlated (R2 = 0.86, p <0.001, slope = -0.82). When using a fast sampling of 47 Hz, DSCF captured pulsatile CBF, respiration, and heartbeat signals. Importantly, the observed correlation between rCBF and ICP suggests the potential of DSCF to be used for extracting ICP information from the measured pulsatile CBF waveform changes.