Measurement of hemodynamic parameters The ulnar artery and radial artery is located at 1 cm proximal to the ulnar or radial styloid process. Specific points will be located with skin marker to provide consistency with all measurements taken. Hemodynamic parameters will is measured by Pulsed-wave Doppler (PWD) ultrasound. The probe will be placed on the ventral wrist parallel to the long axis of the forearm without undue pressure on the artery during the PWD measurements. The volume gate will be positioned in the center of the arterial lumen, and the size of the gate will be 1/3 lumen of the artery. The angle of insonation is adjusted and maintained at 50-60 degrees. Once a desired PWD spectral waveform is achieved, the arterial hemodynamic parameters will be recorded.