Table 3.

Findings on fNIRS biomarkers of depth of anesthesia.

Study	N	Anesthetics tested	Aim	Main findings
Izzetoglu et al. [52]	26	Sevoflurane and desflurane	To determine neuromarkers that can differentiate between light and deep anesthesia	Found a significant difference in Hb between deep and light anesthetic stages. The mean values indicate that light anesthesia is associated with lower Hb. The effect was seen most predominantly in the right hemisphere. Deep anesthesia was also associated with a slow rate of change in Hb, whereas light anesthesia was associated with a high rate of change
Leon-Dominguez et al. [53]	20	Propofol and sevoflurane	To examine the contribution of the human prefrontal cortex to the emergence and suppression of consciousness	Propofol causes a significant increase in Hb after induction in the left and right PFC. Removal of sevoflurane during emergence causes a significant decrease in the levels of Hb in the right PFC
Curtin et al. [54]	41	Propofol	To provide an initial evaluation into the benefits of fNIR for the monitoring of patients during GI endoscopy	fNIR can detect a dose dependent response to the infusion of propofol during a GI sedation regime. Significant increases were found in HbO2 concentration following propofol administration