Doppler Ultrasound Normal frequency and volume of audio signal Normal waveform pattern No evidence of vascular stenosis or obstruction Doppler ultrasound probe transmits high frequency sound waves that are directed at a specific blood vessel, and records waveform on graph paper To detect stenosis or occlusion in an artery or vein To diagnose the peripheral artery or cerebrovascular disease To evaluate the results of arterial reconstruction or vascular bypasssurgery To assess for possible Trauma to an artery Arterial stenosis or occlusion Venous Thrombosis Venous valvular incompetency Nicotine Alcohol Caffeine Anxiety Uncooperative behavior