Light-reflective cerebral oximetry and jugular bulb venous oxygen saturation during carotid endarterectomy

Abstract

A novel instrument using reflected near-infra-red light spectroscopy to measure cerebral oxygen saturation non-invasively was evaluated during carotid endarterectomy; cerebral perfusion was compared with jugular bulb venous oxygen saturation and transcranial Doppler ultrasonographic measurements. Initially, oximetry sensors with light source-detector separation distances of 10 and 27 mm were positioned over the frontal area, while a cannula positioned in the jugular bulb permitted sampling for jugular bulb venous oxygen saturation. To increase cerebral oxygen saturation sensitivity, modified sensors with light source-detector separation distances of 30 and 40 mm were relocated over the middle cerebral artery territory. The changes in cerebral and jugular bulb venous oxygen saturation, and in peak blood flow velocity before and 30 s after carotid clamping and declamping were recorded. The modified cerebral perfusion system achieved improved correlations between cerebral and jugular bulb venous oxygen saturation changes during carotid clamping and declamping (r = 0.92, P < 0.001). The correlation between change in cerebral oxygen saturation and the percentage change in peak flow velocity on both cross-clamping and declamping was equally strong (r = 0.90, P < 0.001). Near-infra-red cerebral spectroscopy reliably detects changes in cerebral oxygen saturation during carotid endarterectomy and may have wide applications in monitoring brain perfusion during neurosurgery and cardiopulmonary bypass surgery, and in closed head injury.

Tissue Oxygen Index

“…In adults, normal TOI values have been reported to range from 65% to 85%. 14,36 -41 Although a number of authors have compared NIRS with other techniques such as jugular bulb oxygen saturation (SjO 2 ), transcranial Doppler ultrasonography and somatosensory-evoked potential 15,37,[42][43][44][45][46][47][48][49][50][51][52][53][54][55][56] or with neurologic events, few have attempted to define an absolute threshold for ischemia. 13,14,16,17,46,[57][58][59] Most studies of this type using NIRS make no attempt to correct for extracranial contributions to signal changes.…”

Comparison of Near-Infrared Spectroscopy and Somatosensory Evoked Potentials for the Detection of Cerebral Ischemia During Carotid Endarterectomy

“…However, previous studies failed to demonstrate the clinical usefulness of the cerebral oximeter INVOS 3100A in carotid surgery. One reason was the use of reference methods, such as jugularvenous oximetry, 10 that are well recognized as unreliable for detection of focal ischemia. 17 Furthermore, because of the limited number of patients studied, comparison of the NIRS results with individual neurological outcome did not provide conclusive evidence for the usefulness of this device.…”

“…Previous studies provided evidence that changes in cerebral oxygenation caused by cross-clamping of the ICA can be monitored by means of near-infrared spectroscopy (NIRS). [7][8][9][10] Since no "gold standard" with which to test the sensitivity and specificity of cerebral oximetry exists, the results of NIRS need to be compared with other validated forms of neuromonitoring. 11 A loss of cortical SEP is a good indicator of cerebral hypoperfusion and is able to identify patients at risk for intraoperative stroke.…”

Detection of cerebral ischemia in neurovascular surgery using quantitative frequency-domain near-infrared spectroscopy

“…Data from previous studies demonstrated that absolute numbers of regional SO 2 are of little value in interpreting results obtained by semiquantitative NIRS. 6,8,26,28,32,40,41 Recently, Q-NIRS measurements were introduced, which enabled accurate quantification of brain tissue oxygenation. Quantitative frequency-domain NIRS has two major advantages compared with CW-NIRS: it provides quantitative values of hemoglobin concentrations (HbO 2 , HHb, tHb), and it directly monitors brain tissue oxygenation independently from oxygenation of the skin and scalp.…”