Near-Infrared Spectroscopy for the Evaluation of Anesthetic Depth

Abstract

The standard-of-care guidelines published by the American Society of Anesthesiologists (ASA) recommend monitoring of pulse oximetry, blood pressure, heart rate, and end tidal CO2 during the use of anesthesia and sedation. This information can help to identify adverse events that may occur during procedures. However, these parameters are not specific to the effects of anesthetics or sedatives, and therefore they offer little, to no, real time information regarding the effects of those agents and do not give the clinician the lead-time necessary to prevent patient “awareness.” Since no “gold-standard” method is available to continuously, reliably, and effectively monitor the effects of sedatives and anesthetics, such a method is greatly needed. Investigation of the use of functional near-infrared spectroscopy (fNIRS) as a method for anesthesia or sedation monitoring and for the assessment of the effects of various anesthetic drugs on cerebral oxygenation has started to be conducted. The objective of this paper is to provide a thorough review of the currently available published scientific studies regarding the use of fNIRS in the fields of anesthesia and sedation monitoring, comment on their findings, and discuss the future work required for the translation of this technology to the clinical setting.

Design of multichannel functional near-infrared spectroscopy system with application to propofol and sevoflurane anesthesia monitoring

“…Also, the CTHR index changed in both the induction and awakening processes. The relative HbO 2 fluctuation had a similar trend, 28 while the trend is opposite in the case of Hb. 28 Interestingly, the Hb indices have similar trends in induction phase with another study, 48 which used propofol induction.…”

“…53,54 Hemandez-Meza et al had used the NIRS to measure the prefrontal activity during the induction and recovery states of GA, as well as compare the Hb value with BIS in outpatient elective colonoscopy and coloproctology surgery. 21,28,33 The results showed that the fNIRS have potential in assessing the DoA. However, there are still many problems.…”

“…The design principle of the device is based on the principle of frequency-division multiplexing, which is widely adopted in the field, such as CW5, Braininsight NIRS, ETG-7100, and CW6. 28,47 Compared to these existing commercial instruments, there are several advantages of our system: i. Higher sampling rate (100 kHz) and smaller size (using FPGA as the main processor).…”

“…25,26 The food and drug administration has approved four cerebral oximeter devices for clinical monitoring: the CerOx (Ornim, Foxboro, Massachusetts), Equanox (Nonin Medical,However, the oximetry of FORE-SIGHT and INVOS can only supply physiological changes rather than changes with cognitive activity. 28 Further, quantities measured by these devices may be altered by many factors, such as cardiac output, hypo/hypercapnia, temperature, and local blood flow. Additionally, indices must be interpreted in the context of available clinical information if they are supposed to be used to track anesthesia process.…”

“…It was found that oxygen saturation is sensitive to inspire oxygen and subject position. 34,35 Hernandez-Meza et al 28 provided a thorough review of the use of fNIRS in the fields of anesthesia and sedation monitoring. It is clear that there are still many problems to be solved in using fNIRS to monitor brain states under GA in clinic.…”