 Cerebral oxygenation will be assessed using near - infrared spectroscopy . Two near-infrared sensors will be placed on the skin over the right and left prefrontal cortex region of the forehead, and the signals were averaged to determine cerebral oxygenation. The sensors will be secured to the skin using double-sided adhesive tape and shielded from ambient light using an elastic bandage. The sensors alternately emit near-infrared light at wavelengths of 730 and 810 nm. Each sensor contains two detectors located at 3 and 4 cm from the emitting source that detect oxygenated and deoxygenated states of Hb to estimate regional O2 saturation based on internal algorithms Rasmussen et al. 2007. 