Near-Infrared Spectroscopy for the Evaluation of Anesthetic Depth

Table 1

Findings on the effect of anesthetics on cerebral hemodynamics.

Study		Anesthetics tested	Aim	Main findings
Lovell et al. [34]	36	Propofol, thiopental, and etomidate	To study the ability of NIRS to detect changes in cerebral oxygenation associated with the induction of anesthesia	The area under the [HbO2]-time curve showed significant changes with the induction of anesthetics and time. The area under the [Hb]-time curve did not significantly change with time or induction of anesthetic. The area under the [HbT]-time curve showed significant changes with respect to time and induction of anesthetic. Propofol and thiopental showed increase in the area under the curve of [HbO2] and [HbT] while etomidate showed a decrease of the same parameters
Fleck et al. [35]	32	Propofol	To measure cerebral oxygen and blood supply changes after propofol infusion in children with congenital heart disease	Propofol sedation caused significant increase in tissue oxygenation index while leading to significant decreases in mean arterial pressure and cardiac index
Iwasaki et al. [36]	34	Sevoflurane and propofol	To compare the induction time and changes in cerebral blood volume during induction with 8% sevoflurane, 5% sevoflurane, or propofol	HbO2 and HbTot were significantly greater after intubation of the 8% sevoflurane group
Valencia et al. [37]	48	Sevoflurane and propofol	To investigate differences in cerebral oxygen saturation between sevoflurane and propofol	Baseline adjusted oxygen saturation was significantly higher in the sevoflurane group
Fassoulaki et al. [38]	24	Sevoflurane and desflurane	To study the effect of different concentrations of sevoflurane and desflurane on cerebral oxygenation	At equipotent concentrations there were no significant differences in oxygen saturation between sevoflurane and desflurane. For both sevoflurane and desflurane, higher anesthetics concentrations were associated with significantly higher oxygen saturation values
Kanemaru et al. [39]	36	Midazolam, isoflurane, and aminophylline in addition to propofol	To study the influence of midazolam, isoflurane, and aminophylline on BIS and rSO2 when administered during propofol anesthesia maintenance	Midazolam and isoflurane administration during propofol anesthesia caused significant decreases in BIS value without affecting rSO2. Aminophylline caused an increase in BIS value without affecting rSO2
Owen-Reece et al. [40]	11 conscious subjects, 11 anesthetized subjects	Isoflurane and fentanyl	To compare measurements of CBF between healthy volunteers and anesthetized subjects (fentanyl and isoflurane). To compare measurements of CBF, during anesthesia, using fibers placed on the scalp versus the dura	A significant change in CBF was not observed as a result of anesthesia (isoflurane and fentanyl). Measurements of CBF at the dura were significantly higher than the CBF measured at the scalp
Casati et al. [41]	60	Sevoflurane	To evaluate rSO2 and frequency of cerebral desaturation events in healthy elderly patients during abdominal surgery	Cerebral desaturation occurred in 16 patients. Postoperative cognitive decline was observed in six patients with cerebral desaturation and six patients without desaturation. Cerebral desaturation during surgery was associated with longer hospital stays