Measurement of regional cerebrovascular haemoglobin oxygen saturation in cats using optical spectroscopy.
We describe the use of optical spectroscopy in the near infra-red light range to non-invasively measure regional cerebral haemoglobin oxygen saturation (rSHbO2) in cats during progressive cerebral hypoxia. This technique differs from spectroscopic techniques previously described in that the concentration ratio--percentage haemoglobin: oxygen saturation--is quantified. This saturation is the weighted summation of saturation in the cerebrovascular system: arterial, venous, and capillary beds. In a cat model of progressive cerebral hypoxia, a positive linear correlation between this regional measurement of cerebral saturation and actual saturation, calculated from cerebral arterial and mixed venous blood, was noted (n = 20, r = 0.88, p less than 0.01). The spectroscopic measurement rSHbO2 is also used to index cerebral oxygen extraction. During hypoxia spectroscopic indexed oxygen extraction (iOE) and cerebral arterial-venous difference in oxygen content were simultaneously measured. A least-squares positive linear correlation between these two parameters was noted [AVDO2 = iOE (0.05) + 4.4] (n = 40, r = 0.6, s = 1.2). Objective measurement of 'regional cerebrovascular haemoglobin saturation' and an index of cerebral oxygen extraction are possible using optical spectroscopy.
Henry Ford Neurosurgical Institute, Henry Ford Hospital, Detroit, MI 48202.
P W
PW
McCormick
M
M
Stewart
P
P
Ray
G
G
Lewis
M
M
Dujovny
J I
JI
Ausman
D000465:Algorithms; D000818:Animals; D001923:Brain Chemistry; D001931:Brain Mapping; D002415:Cats; D002560:Cerebrovascular Circulation; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption; D010108:Oxyhemoglobins / Q000032:analysis*; D013055:Spectrophotometry, Infrared
D010108:Oxyhemoglobins; D010100:Oxygen