What penile/brachial index would be suggestive of vasculogenic impotence?

A penile/brachial index (PBI) is a diagnostic tool used to assess blood flow and vascular health in relation to erectile function. The PBI is calculated by measuring the systolic blood pressure in the penis and comparing it to the systolic blood pressure in the arm (brachial artery).

A PBI of 0.6 is suggestive of vasculogenic impotence because it indicates that there is a significant discrepancy in blood flow between the penile and brachial circulation. Specifically, values below 0.75 are typically associated with erectile dysfunction due to insufficient blood flow. A PBI of 0.6 implies that blood flow to the penis is inadequate for normal erectile function, signaling potential vascular issues.

Higher values, such as 0.7 and above, usually indicate that there may be sufficient blood flow for erectile function, while lower values (such as 0.4 or 0.5) can be signs of more severe vascular compromise. Thus, the PBI of 0.6 effectively indicates a moderate level of vascular dysfunction, aligning with a diagnosis of vasculogenic impotence.