Lack of predictive correlation between peripheral arterial tone and colour flow Doppler parameters in men with erectile dysfunction

Objective To evaluate whether peripheral arterial tone (PAT) can predict the results of penile colour flow Doppler in the evaluation of erectile dysfunction (ED). Patients and Methods Fifty men presenting to an ED clinic were tested with an Endo-PAT2000 machine (Itamar Medical, Caesarea, Israel), which assessed augmentation index (AI), a measure of arterial stiffness, and reactive hyperaemia index (RHI), a measure of endothelial vasodilatation. Penile haemodynamics were measured and used to identify both arterial insufficiency (abnormal peak systolic velocity [PSV]) and veno-occlusive disease (abnormal end diastolic velocity [EDV]) after pharmacological erection with prostaglandin E1 using colour flow Doppler. Between-group comparisons were carried out using a Wilcoxon rank-sum test for continuous variables and a chi-squared test for categorical variables. Simple and multivariable logistic regression analyses were used to analyse the correlation between outcome measures. Results Using Doppler analysis, 58% of patients were found to have arterial insufficiency (abnormal PSV) and 48% had veno-occlussive disease (abnormal EDV). Using the Endo-PAT machine, 44% of patients were found to have increased arterial stiffness (abnormal AI) and 54% had decreased endothelial relaxation (abnormal RHI). Neither AI nor RHI were correlated with PSV or EDV. The closest association was between high AI and low PSV, with a sensitivity of 0.55 and specificity of 0.71. Conclusions In our patient cohort, PAT did not reliably predict the results of penile Doppler. The two tests appear to measure different although potentially complementary aspects of the local and systemic vasculature.