THE CALCULATION OF CARDIAC OUTPUT AND EFFECTIVE PERIPHERAL RESISTANCE FROM BLOOD PRESSURE MEASUREMENTS WITH AN APPENDIX ON THE SIZE OF THE AORTA IN MAN

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Abstract
The pulse pressure is found to be correlated with the stroke volume, if lateral pressures are measured, if the form of the pulse curve is taken into consideration, and if the distensibility of the large vessels is estimated from pulse wave velocity determinations. In such calculations the size of the vessels, which vary both with the size and age of the individual, is important. Data from the literature are analyzed in re-lation to the effect of age on the volumes contained in the vessels, and values are submitted of the lateral pressures and pulse wave velocities (heart to subclavian, subclavian to femoral, subclavian to brachial, and femoral to dorsalis pedis) in subjects varying in age from 21 to 76. The constants used are shown to give values for cardiac output by calculation which differ from those obtained by the acetylene method on the average by less than 12%. The effective peripheral resistance is estimated from the relationship of mean pressure to the cardiac index. For the equations used the original paper should be consulted. Comparisons are also given with cardiac output estimated on the same subjects by Starr and Gamble''s modified ethyl iodide method. Most of the data were obtained with the subjects lying down and basal, a few with the subjects standing, sitting or after meals.