Theory of the measurement of arterial compliance in humans.

Experimental determinations of the arterial compliance C are discussed, based on a simplified formula involving the systolic and diastolic pressures, the period of diastole and the peripheral resistance. The resistance is expressed in terms of the cardiac output and the mean arterial pressure during diastole, which is derived from an assumed exponential pressure-time curve and leads to a still simpler expression for C. The cardiac output is obtained by a rebreathing method that yields arterial and venous P co 2, the latter from extrapolation based on a linear difference equation. The experimental standard error of the compliance in terms of those of the various physiological parameters is considered. Numerical examples are given for a healthy man.