ENGINEERING ANALYSIS OF PENILE HEMODYNAMIC AND STRUCTURAL-DYNAMIC RELATIONSHIPS - PART III - CLINICAL CONSIDERATIONS OF PENILE HEMODYNAMIC AND RIGIDITY ERECTILE RESPONSES

Purpose: The extent to which hemodynamic erectile responses predict pe nile buckling forces has not previously been analytically investigated . An engineering study was performed to compare hemodynamic data with penile buckling force values. Methods: Dynamic infusion pharmacocavern osometry studies in 21 impotent patients (age 43, range 24-62 y) were accomplished to obtain information during penile erection concerning h emodynamic values, penile buckling forces and their determinants: intr acavernosal pressure, erectile tissue mechanical properties and penile geometry. Results: In the 21 patients, discrepancies existed in sever al patients who demonstrated normal hemodynamic values (low now-to-mai ntain and high equilibrium intracavernosal pressures) but elevated cav ernosal compliance values and diminished penile buckling forces. There was poor correlation between cavernosal compliance and equilibrium in tracavernosal pressure (r = -0.36); better correlation between complia nce and expandability (r = -0.72) and best correlation between dimensi onless compliance and the dimensionless product of expandability with equilibrium pressure (r = -0.88). These data implied that cavernosal c ompliance was dependent on multiple factors, not only equilibrium intr acavernosal pressure. Conclusions: Hemodynamic indices which correlate with intracavernosal pressure alone do not predict penile buckling fo rces since the latter are dependent not only on intracavernosal pressu re but also on penile geometry and erectile tissue properties. The mos t relevant tissue property in predicting adequate penile buckling forc es is cavernosal expandability. A new impotence classification system and diagnostic algorithm based on the determinants of penile rigidity and not exclusively on hemodynamic responses is proposed.