Cerebral monitoring during carotid endarterectomy using near-infrared diffuse optical spectroscopies and electroencephalogram

Abstract

Intraoperative monitoring of cerebral hemodynamics during carotid endarterectomy (CEA) provides essential information for detecting cerebral hypoperfusion induced by temporary internal carotid artery (ICA) clamping and post-CEA hyperperfusion syndrome. This study tests the feasibility and sensitivity of a novel dual-wavelength near-infrared diffuse correlation spectroscopy technique in detecting cerebral blood flow (CBF) and cerebral oxygenation in patients undergoing CEA. Two fiber-optic probes were taped on both sides of the forehead for cerebral hemodynamic measurements, and the instantaneous decreases in CBF and electroencephalogram (EEG) alpha-band power during ICA clamping were compared to test the measurement sensitivities of the two techniques. The ICA clamps resulted in significant CBF decreases (-24.7 ± 7.3%) accompanied with cerebral deoxygenation at the surgical sides (n = 12). The post-CEA CBF were significantly higher (+43.2 ± 16.9%) than the pre-CEA CBF. The CBF responses to ICA clamping were significantly faster, larger and more sensitive than EEG responses. Simultaneous monitoring of CBF, cerebral oxygenation and EEG power provides a comprehensive evaluation of cerebral physiological status, thus showing potential for the adoption of acute interventions (e.g., shunting, medications) during CEA to reduce the risks of severe cerebral ischemia and cerebral hyperperfusion syndrome.

Near-infrared diffuse optical monitoring of cerebral blood flow and oxygenation for the prediction of vasovagal syncope

“…The details about the DCS flow-oximeter can be found elsewhere. [19][20][21] Briefly, long-coherence length (>5m) NIR lights generated by two continuous-wave laser diodes (785 and 854 nm, 100 mW, CrystaLaser Inc., Reno, Nevada) were delivered alternately to tissues via two multimode source fibers (core diameter of each fiber ¼ 200 μm, emission area ¼ 0.13 mm 2 ) bundled tightly together. Each laser was switched on for 450 ms with a 50-ms interval for the transition between the two lasers.…”

“…This separation allowed for the detection of cerebral hemodynamics in the adult prefrontal cortex. 12,20 The blood flow measurement was achieved by monitoring the light intensity fluctuations in a single speckle area covered by the single-mode fiber in the tissue surface. Fluctuations detected by the APDs resulted from the motion of moving scatterers, primarily RBCs in tissue microvasculature.…”

“…[19][20][21] DCS for blood flow measurement has been extensively validated against other techniques in various organs/tissues, including Doppler ultrasound in premature infant brain, 22 power spectral Doppler ultrasound in murine tumors, 23 laser Doppler flowmetry in mouse brains, 21 fluorescent microsphere measurement of CBF in piglet brain, 24 ASL-MRI in human muscle, 25 and Xenon computed tomography in traumatic brain, 26 while DCS flow-oximeter for oxygenation measurement has been validated against commercial NIRS oximeter (Imagent, ISS Inc., Champaign, Illinois). 19 In this study, we used a finger plethysmograph and a custom-designed DCS flow-oximeter to concurrently monitor the blood pressure and dynamic changes of CBF, concentrations of HbO 2 (½HbO 2 ), Hb ([Hb]) and total hemoglobin (THC) in healthy subjects during 70 deg HUT tests.…”

Application of full field optical studies for pulsatile flow in a carotid artery phantom

“…For the case of a strong diffuser a different speckle pattern is observed compared to a weak diffuser. Another similar technique is diffusion correlation spectroscopy [20]. This is an extension of single-scattering dynamic light scattering, which non-invasively measures local blood flow.…”

Near-infrared diffuse correlation spectroscopy in cancer diagnosis and therapy monitoring

“…[25][26][27] DCS can be easily and continually applied at the bedside in clinical rooms. [28][29][30][31][32][33][34] 35 and has been used less in the "cancer" context than in other scenarios such as brain and muscle. Therefore, a review of potential for cancer applications of DCS is valuable at this time for both optical and cancer communities.…”