If there is little or no increase of blood flow velocity during POSTocclusive reactive hyperemia, what condition is likely present?

When there is little or no increase in blood flow velocity during postocclusive reactive hyperemia, it suggests a significant obstructive disease is likely present. In a healthy vascular system, occluding the blood flow temporarily should cause a buildup of metabolites and a subsequent release that triggers vasodilation and increases blood flow. This results in a marked increase in blood flow velocity once the occlusion is removed.

If obstructive disease is present, such as severe atherosclerosis or arterial stenosis, the ability of the blood vessels to dilate appropriately in response to increased demand is compromised. This means that even after the occlusion is released, the higher blood flow velocity expected won't be observed due to limitations imposed by the obstruction.

Normal arterial function, in contrast, would result in a significant increase in flow velocity, and conditions like vasodilation or just mild peripheral resistance would still typically allow for some degree of increase in blood flow following the removal of an occlusion. Therefore, the absence or minimal change in blood flow velocity is a key indicator of significant obstructive disease.