title: Continuous monitoring of absolute cerebral blood flow by near-infrared spectroscopy during global and focal temporary vessel occlusion.
abstract: Treatment of intracranial aneurysms by surgical clipping carries a risk of intraoperative ischemia, caused mainly by prolonged temporary occlusion of cerebral arteries. The objective of this study was to develop a near-infrared spectroscopy (NIRS) technique for continuous monitoring of cerebral blood flow (CBF) during surgery. With this approach, cerebral hemodynamics prior to clipping are measured by a bolus-tracking method that uses indocyanine green as an intravascular contrast agent. The baseline hemodynamic measurements are then used to convert the continuous Hb difference (HbD) signal (HbD = oxyhemoglobin - deoxyhemoglobin) acquired during vessel occlusion to units of CBF. To validate the approach, HbD signal changes, along with the corresponding CBF changes, were measured in pigs following occlusion of the common carotid arteries or a middle cerebral artery. For both occlusion models, the predicted CBF change derived from the HbD signal strongly correlated with the measured change in CBF. Linear regression of the predicted and measured CBF changes resulted in a slope of 0.962 (R(2) = 0.909) following carotid occlusion and 0.939 (R(2) = 0.907) following middle cerebral artery occlusion. These results suggest that calibrating the HbD signal by baseline hemodynamic measurements provides a clinically feasible method of monitoring CBF changes during neurosurgery.
authors: Imaging Division, Lawson Health Research Institute, 268 Grosvenor St., London, ON, Canada N6A 4V2.
authors: Joel A
authors: JA
authors: Cooper
authors: Kenneth M
authors: KM
authors: Tichauer
authors: Melfort
authors: M
authors: Boulton
authors: Jonathan
authors: J
authors: Elliott
authors: Mamadou
authors: M
authors: Diop
authors: Miguel
authors: M
authors: Arango
authors: Ting-Yim
authors: TY
authors: Lee
authors: Keith
authors: K
authors: St Lawrence
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D015415:Biomarkers / Q000097:blood; D001783:Blood Flow Velocity; D017536:Carotid Artery, Common / Q000503:physiopathology* / Q000601:surgery; D016893:Carotid Stenosis / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D002560:Cerebrovascular Circulation; D004396:Coloring Agents; D004195:Disease Models, Animal; D006454:Hemoglobins / Q000378:metabolism; D007208:Indocyanine Green; D020244:Infarction, Middle Cerebral Artery / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D008026:Ligation; D016014:Linear Models; D020768:Middle Cerebral Artery / Q000503:physiopathology* / Q000601:surgery; D008955:Models, Cardiovascular; D016343:Monitoring, Intraoperative / Q000379:methods*; D010108:Oxyhemoglobins / Q000378:metabolism; D011237:Predictive Value of Tests; D012039:Regional Blood Flow; D015203:Reproducibility of Results; D019265:Spectroscopy, Near-Infrared; D013552:Swine; D013997:Time Factors; D014886:Weaning
chemical_list: D015415:Biomarkers; D004396:Coloring Agents; D006454:Hemoglobins; D010108:Oxyhemoglobins; C100003:deoxyhemoglobin; D007208:Indocyanine Green