CHANGES IN ARTERIAL AND VENOUS BLOOD PRESSURE AND FLOW DISTAL TO A CUFF INFLATED ON THE HUMAN ARM

Abstract

The effects of inflating a cuff around the upper arm upon arterial and venous pressure distally were recorded with Hamilton manometers. When inflated at pressures less than diastolic, the cuff caused no change in distal arterial pressure, but produced a prompt, steady rise in venous pressure to about the same level as that in the cuff. When inflated at pressures greater than diastolic, the cuff caused either no change, an increase, or a decrease in arterial pressure distally, depending upon the pressure in the cuff and the resting blood flow in the part. Thus, the higher the cuff pressure (within limits) and the lower the flow, the greater the enhancement of diastolic and mean arterial pressure distally. When pressure in the cuff was too high it caused a decrease in systolic and mean pressure. When the cuff was inflated at suprasystolic pressures, distal arterial pressure fell in a smooth curve to, or slightly below, venous pressure, which rose. Venous pressure rose when the upper cuff was inflated at supradiastolic pressures similarly as at infradiastolic pressures, except that the rate of rise varied directly with the resultant distal mean arterial pressure. Likewise, the rate of rise of plethysmographic blood flow measurements could be increased by applying the proper pressure in the upper cuff. These findings indicate that increases in distal arterial pressure produced by inflating the cuff at certain supradiastolic pressures are due to a reduction of regurgitant arterial flow and are associated with increases in forward blood flow distally. Such increases are maintained only briefly until venous pressure and resistance rise high enough to impede the flow.