NONINVASIVE MEASUREMENT OF THE HUMAN BRACHIAL-ARTERY PRESSURE-AREA RELATION IN COLLAPSE AND HYPERTENSION

A noninvasive method to obtain pressure-lumen area (P-A) measurements of the human brachial artery is introduced. The data obtained from thi s method are analyzed using a mathematical model of the relationship b etween vessel pressure and lumen area including vessel collapse and hy pertension. An occlusive arm cuff is applied to the brachial artery of ten normal subjects. The cuff compliance is determined continuously b y means of a known external volume calibration pump. This permits the computation of the P-A curve of the brachial artery under the cuff. A model is applied to analyze the P-A relation of each subject. The resu lts show that the lumen area varies considerably between subjects. The in vivo resting P-A curve of the brachial artery possesses features s imilar to that of in vitro measurements. A primary difference is that the buckling pressure is higher in vivo, presumably due to axial tensi on, as opposed to in vitro where it is near zero or negative. It is fo und that hypertension causes a shift in the P-A curve towards larger l umen areas. Also, the compliance-pressure curve is shown to shift towa rds higher transmural pressures. Increased lumen area provides an adap tive mechanism by which compliance can be maintained constant in the f ace of elevated blood pressure, in spite of diminished distensibility. (C) 1998 Biomedical Engineering Society. [S0090-6964(98)01306-X].