title: Cerebral blood flow assessment with indocyanine green bolus transit detection by near-infrared spectroscopy in the rat.
abstract: In this study we evaluated the feasibility of measuring cerebral blood flow in rats by monitoring the transit of an indocyanine green bolus through the brain with multiwavelength near-infrared spectroscopy. Different volumes of a 1 mg/ml indocyanine green solution (5, 15, 25, 50 microl) were injected intravenously in the search for an optimal dose. Clear transit curves were obtained with all doses and a blood flow index could easily be determined. The indocyanine green signal obtained with the bolus of 5 microl rapidly returned to baseline and interfered minimally with the haemoglobin and cytochrome oxidase signals. This dose was used in a second study to evaluate the reproducibility of the signal and the effect of hypercapnia. Two groups of rats received 7 repetitive boli of indocyanine green. In one group, 7% CO(2) was added to the gas mixture before the second, fourth and sixth indocyanine green injection. Hypercapnia consistently caused a significant increase in blood flow index, cerebral haemoglobin concentration and O(2)-saturation. In the control group these variables remained stable in time. We conclude that monitoring of the transit of an indocyanine green bolus with multiwavelength near-infrared spectroscopy can be used to assess cerebral blood flow qualitatively in rats in combination with continuous monitoring of brain oxygenation.
authors.affiliation: Department of Physiology, CARIM, University of Maastricht, Maastricht, The Netherlands. gdvissch@janbe.jnj.com
authors.forename: Geofrey
authors.initials: G
authors.lastname: De Visscher
authors.forename: Koen
authors.initials: K
authors.lastname: van Rossem
authors.forename: Jos
authors.initials: J
authors.lastname: Van Reempts
authors.forename: Marcel
authors.initials: M
authors.lastname: Borgers
authors.forename: Willem
authors.initials: W
authors.lastname: Flameng
authors.forename: Robert S
authors.initials: RS
authors.lastname: Reneman
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity; D002560:Cerebrovascular Circulation; D006935:Hypercapnia / Q000503:physiopathology; D007208:Indocyanine Green / Q000008:administration & dosage; D008297:Male; D008991:Monitoring, Physiologic; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D013687:Telencephalon / Q000098:blood supply*; D013997:Time Factors
chemical_list: D007208:Indocyanine Green