Pressure-flow relationships in the ascending aorta and femoral artery of man

Using a Kolin-Kado electromagnetic flowmeter and a 20-gauge needle connected to a Statham transducer, instantaneous blood flow and pressure were measured in the ascending aorta of 3 patients and in the common femoral artery of 11 patients. From the data obtained in the ascending aorta the peak blood flow, cardiac output, peak power, and stroke work were calculated. Harmonic analysis of the pressure and flow curves was carried out and the hydraulic input impedance series was calculated for each subject. The constant term (peripheral vascular resistance) was found to be about 12 times as large as the largest time-dependent impedance term. Similar analysis of the femoral artery data indicated: 1) the moduli of the hydraulic input impedance series dropped with frequency from an initially high constant term, and then varied slightly with frequency thereafter; and 2) the vascular resistance decreased to 75% of the control value during reactive hyperemia and increased to 232% of the control value following norepinephrine administration. hydraulic input impedance Submitted on June 4, 1964