PEAK SYSTOLIC VELOCITY AND FLOW-VOLUME INCREASE WITH BLOOD-PRESSURE IN LOW-RESISTANCE SYSTEMS

This study demonstrates that when vascular resistance is low, peak sys tolic velocity and peak flow volume increase with increasing blood pre ssure. We used ischemia with reactive hyperemia to create reproducible low resistance conditions in 32 volunteers. Ischemia resulted in shar p increases in systolic and diastolic velocities, while the difference between these velocities increased minimally. Spontaneous variations in subject's systolic blood pressure were positively correlated with p eak systolic volume and peak flow volume (r = 0.40 and 0.59 respective ly), but resistive index was not. We conclude that low resistance flow is blood pressure dependent. Because blood pressure increases with ag e, tumor velocity and frequency shift thresholds may need blood pressu re correction if applied over wide age ranges. The resistive index was independent of blood pressure and thus may be preferable.