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7125795 
Journal Article 
Impact of Extracranial Contamination on Regional Cerebral Oxygen Saturation A Comparison of Three Cerebral Oximetty Technologies 
Davie, SN; Grocott, HP; , 
2012 
1 
Anesthesiology
ISSN: 0003-3022
EISSN: 1528-1175 
LIPPINCOTT WILLIAMS & WILKINS 
PHILADELPHIA 
116 
4 
834-840 
English 
22343469 
WOS:000301997900013 
Background: Cerebral oximetry is a noninvasive technology using near-infrared spectroscopy (NIRS) to estimate regional cerebral oxygen saturation. Although NIRS cerebral oximetry is being increasingly used in many clinical settings, inter-device technologic differences suggest potential variation in the ability to accurately acquire brain oxygenation signals. The primary objective of this study was to determine if NIRS-derived regional cerebral oxygen saturation measurements accurately account for oxygen saturation contamination from extracranial tissue.Methods: Twelve healthy volunteers had each of three NIRS devices (FORE-SIGHT [CAS Medical Systems Inc; Brand-ford, CT], INVOS 5100C-PB [Covidien; Boulder, CO], and EQUANOX Classic 7600 [Nonin Medical Inc; Plymouth, MN]) randomly applied to the forehead. After this, a circumferential pneumatic head cuff was positioned such that when inflated, hypoxia-ischemia would be produced in the extracranial scalp tissue beneath the NIRS cerebral oximeters. Comparisons among the three devices were made of the NIRS measurements before and following hypoxia-ischemia produced in the scalp tissue with inflation of the head cuff.Results: The induction of extracranial hypoxia-ischemia resulted in a significant reduction in regional cerebral oxygen saturation measurements in all three NIRS devices studied. At 5 min postinflation of the pneumatic head cuff, the INVOS demonstrated a 16.6 +/- 9.6% (mean +/- SD) decrease from its baseline (P = 0.0001), the FORE-SIGHT an 11.8 +/- 5.3% decrease from its baseline (P < 0.0001), and the EQUANOX a 6.8 +/- 6.0% reduction from baseline (P = 0.0025).Conclusions: Extracranial contamination appears to significantly affect NIRS measurements of cerebral oxygen saturation. Although the clinical implications of these apparent inaccuracies require further study, they suggest that the oxygen saturation measurements provided by cerebral oximetry do not solely reflect that of the brain alone.