Impact of Extracranial Contamination on Regional Cerebral Oxygen Saturation

Abstract

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.

Extracranial contamination in the INVOS 5100C versus the FORE-SIGHT ELITE cerebral oximeter: a prospective observational crossover study in volunteers

“…We chose these endpoints as they were similar to those of a previous study focusing on extracranial contamination. 1 The study coordinator manually transcribed all data from both NIRS monitors and from the Phillips monitor on a case report form.…”

“…Patients undergoing cardiac surgery and various operations in the beach chair position may be at risk for cerebral ischemia and subsequent neurologic injury. [1][2][3] Early detection of any cerebral ischemia may allow clinicians to institute therapies that prevent permanent injury to the central nervous system (CNS). Several technologies have been applied in the perioperative setting that may permit real-time detection of cerebral ischemia.…”

“…4 In contrast, near-infrared spectroscopy (NIRS)-based cerebral oximetry is a noninvasive technology that is relatively easy to use and specifically developed to allow clinicians to detect and treat cerebral ischemia in the operating room. [1][2][3][4][5] The degree of oxygen saturation in cerebral tissue (SctO 2 ) can be determined through the use of multi-wavelength light emitters and detectors,. 6 Derived SctO 2 signals represent a mixture of venous and arterial blood (approximately 70% and 30%, respectively) in the cerebral frontal cortex.…”

“…Nevertheless, previous studies suggest that extracranial contamination can influence the measurement of SctO 2 and result in measured values that do not entirely reflect the status of oxygenation in the brain. 1,13 The aim of the present investigation was to compare the effect of extracranial contamination on SctO 2 values as measured by the FORE-SIGHT ELITE vs the INVOS 5100C monitor. We hypothesized that the SctO 2 values measured by the second-generation FORE-SIGHT ELITE would be significantly less affected by extracranial contamination from superficial tissue ischemia than those measured by the first-generation INVOS 5100C monitor.…”

Inter-device differences in monitoring for goal-directed fluid therapy

“…The main disadvantages of NIRS technology are cost and the inability to distinguish between arterial and venous blood, i.e., assuming an arterial to venous ratio of 30:70 may lead to erroneous measurements. Published data on cerebral oximetry devices suggest they suffer from some extracranial contamination of their signals 109 and interdevice differences (which complicate interpretation). 110 …”