Abstract SNACC-27

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Cerebral blood flow measurement by near infrared spectroscopy in carotid endarterectomy

Kato S, Yoshitani K, Ohnishi Y
National cerebral and cardiovascular center, Suita, Osaka, Japan

To evaluate cerebral blood flow(CBF) during carotid endarterectomy(CEA) is very crucial. However, it is difficult to measure CBF in the operating room. Recently, near infrared spectroscopy(NIRS) with high accuracy has developed, which enables to measure regional cerebral blood flow by injection of indocyanine green. Kubler et al. reported that regional cerebral blood flow derived from NIRS correlated well with values assessed by radioactive microspheres in pigs.(Kubler WM, et al. J cereb Blood Flow Metab 1998; 18: 445-56) We have demonstrated preliminary data that BFI as regional cerebral blood flow of the diseased side significantly decreased during clamping the common carotid artery in American Society of Anesthesiologists Annual Meeting 2013. We analyzed the change of the cerebral blood flow by clump the carotid artery in carotid endarterectomy with an increased number of cases.
After approval of institutional ethical board, patients undergoing elective carotid endarterectomy were enrolled in this study. After induction of general anesthesia, NIRS sensor was placed bilaterally 1cm above eyebrow on the scalp. The dye indocyanine green(0.5 mg/kg) was injected pre carotid cross clamping, during carotid cross clamping and after carotid unclamping. After obtaining hemodynamics stability, we injected indocyanine green via cubital vein. The kinetics of an intravenous bolus of indocyanine green was monitored by NIRS(NIRO 200NX, Hamamatsu Photonics, Hamamatsu, Japan). Blood flow index(BFI) was calculated using slope of the concentration of indocyanine green. The impact of the carotid cross clamping on BFI was evaluated.
We studied 45 patients(43 male, 2 female; aged 71±7). Figure depicted BFI of diseased side significantly decreased during carotid cross clumping compared to the level of pre carotid cross clamping.(from 0.14± 0.14 μmol/l/s to 0.087± 0.045 μmol/l/s)(p <0.01) After unclamping the carotid artery, BFI increased significantly.(from 0.087± 0.045 μmol/l/s to 0.12± 0.064 μmol/l/s)(p <0.01) BFI of healthy did not show significant change during the surgery.(pre clamping: 0.12± 0.069 μmol/l/s; during clamping: 0.11± 0.064 μmol/l/s, p = 0.30)(Figure) We maintained significantly high blood pressure during carotid cross clamping.
BFI as regional cerebral blood flow of the diseased side significantly decreased during clamping the common carotid artery, even if high blood pressure was maintained. However, BFI of the healthy side did not show the significant change. By using the BFI derived from NIRS, it is possible to measure the regional cerebral flow during the operation.

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