Abstract: A cardiac output measurement device for the real-time, non-invasive measurement of cardiac output that can be effectively operated by relatively unskilled personnel on a routine monitoring basis in a wide variety of office and hospital conditions. To accomplish this task, the system utilizes a pulsed Doppler ultrasound transducer directed through the suprasternal notch of a patient axially towards the blood flow in the ascending aorta. The device automatically searches the ascending aorta at various predetermined depths to find the depth at which the greatest quality blood velocity reading is detected. An examination is performed at that chosen depth and the device automatically calculates a patient's cardiac output from the Doppler measured velocity combined with an aortic diameter estimation made from the patient's height, weight, and age. The device automatically calculates cardiac velocity, cardiac index, stroke distance, heart rate, and stroke volume.