Abstract
Spectrophotometric methods (IRM) of measuring cerebral blood volume (CBV) provide qualitative estimates of this variable, but to date the method has not been validated. In this study we evaluate IRM with a double-indicator method of CBV measurement. Regional cerebral blood flow (rCBF) was measured by the microsphere method in four pentobarbital dogs. Light at 775, 815 and 905 nm was presented to the brain and changes in relative CBV computed from the reflectance signals. Absolute CBV was calculated from the equation CBV = rCBF/60 × t, where t is the mean transit time of cardiogreen dye injected into a carotid artery monitored via the 815 wavelength. Mild hypercapnia (PaCO2; 34 ± 2 to 54 ± 3 mmHg) increased rCBF from 29 ± 4 to 95 ± 33 ml/min/100gm and shortened t (8.2 ± 1.8 to 6.0 ± 2 sec). CBV increased from 3.7 ± .4 to 8.7 ± 3.6 ml/100gm. Moderate hypercapnia (PaCO2 = 72 ± 4 mmHg) further increased rCBF to 244 ± 69 ml/min/100gm and shortened t to 4.4 ± 2.2 sec. CBV was 14.1 ± 3.8 ml/100gm. In each study a significant correlation was found between the change in relative and absolute CBV measurements. The overall correlation was r = .961. We conclude that IRM is a potentially useful technique for obtaining qualitative, continuous changes in CBV. Supported by NS∼20020.
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Stiff, J., Wilson, D., Hanley, D. et al. 218 VALIDATION OF THE NEAR INFRARED SPECTROPHOTOMETRY METHODOLOGY FOR MEASURING CEREBRAL BLOOD VOLUME CHANGES. Pediatr Res 19, 147 (1985). https://doi.org/10.1203/00006450-198504000-00248
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DOI: https://doi.org/10.1203/00006450-198504000-00248
