Central (aortic or subclavian), brachial, radial and femoral pressure pulses were recorded simultaneously in 12 healthy subjects during conditions of rest, exercise and 70 degree head-up tilt. Peripheral systolic pressure at rest uniformly exceeded the central systolic pressure generated by the same heartbeat. The average radial pulse pressure was 146, 146 and 165 per cent of central pulse pressure during rest, exercise and tilt while radial mean pressures were 94, 93 and 9S per cent of central

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... mean pressures respectively. Summation of the incident pulse wave with reflected waves from the periphery and i-esonance effects in the peripheral arterial systems may produce these changes in pressure and contour. ALTHOUGH measurements of blood / % pressure in man by direct needle punc-JL A . ture are now commonplace, actually, determinations of arterial pressure by this technic, are of relatively recent origin. The average and range of values encountered in man, especially in regard to central arterial pressure pulses, have not as yet been well documented. Direct arterial blood pressure was first recorded in man during limb amputations. Thus, Faivre 1 in 1856 repoi^ted the blood pressure in the femoral artery of man as being 120 mm. of mercury. Merke and Mviller, 2 in 1925, surgically exposed a brachial artery in each of two critically ill patients and inserted T tubes for the recording of pressures. Brachial arterial pressures were obtained by needle puncture in 1931 by Wolf and von Bons-dorfP in a series of normal subjects and of patients with cardiovascular disease. Hypodermic-type manometers were used to record simultaneous pressure pulses in the axillary, femoral and dorsalis pedis arteries by Hamil-From the Section of Physiology, Mayo Clinic and Mnyo Foundation, Rochester, Minn. Abridgment of a portion of the thesis submitted by Dr. Kroeker to the Faculty of the Graduate School, University of Minnesota, in partial fulfillment of the requirements of a degreo of Master of Science in Medicine.