Cerebral blood flow assessment with indocyanine green bolus transit detection by near-infrared spectroscopy in the rat.
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.
De Visscher
Geofrey
G
Department of Physiology, CARIM, University of Maastricht, Maastricht, The Netherlands. gdvissch@janbe.jnj.com
van Rossem
Koen
K
Van Reempts
Jos
J
Borgers
Marcel
M
Flameng
Willem
W
Reneman
Robert S
RS
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
D007208:Indocyanine Green