The value of sildenafil as mode of stimulation in pharmaco-penile duplex ultrasonography

The purpose of this work was to assess whether a single intracavernous inje ction (ICI) of a low dose of the combination of papaverine-phentolamine is replaceable by a high dose of the oral erectogenic agent sildenafil as mode of stimulation during pharmaco-penile duplex ultrasonography (PPDU). Eleve n patients with complaints of erectile dysfunction were included in a cross over study. With an interval of two weeks the patients were exposed to ICI with papaverine/phentolamine (3.75mg/0.125mg) and oral administration with sildenafil (100mg) preceding PPDU. Five patients started with ICL Six patie nts started with sildenafil. In the sildenafil stimulation mode, visual ero tic stimulation (VES) was used to initiate erection. VES was applied by per sonal LCD monitor. Cut-off values to define sufficient arterial response we re: peak flow velocity (PSV) > 25 cm/s and acceleration time (AT) < 72 ms. Cut-off value to define sufficient veno-occlusion was a resistance index <g reater than or equal to> 1.00. Statistical analysis of PPDU parameters show s no significant difference between the two modes of stimulation for arteri al response (PSV, AT), whereas the resistance index, as a parameter of veno -occlusive response was significantly higher in the sildenafil mode. This f inding is confirmed in the clinical translation of the results: two patient s with an insufficient arterial response to ICI had a sufficient arterial r esponse to sildenafil and only one patient showed an insufficient arterial response following sildenafil, whereas the response following ICI was suffi cient. Analysis of veno-occlusive responses shows remarkable differences be tween both modes of stimulation. Whereas following the administration of si ldenafil all veno-occlusive responses were classified as sufficient, seven patients showed an insufficient veno-occlusive response following ICI. As m ode of stimulation in PPDU, high dose sildenafil yields significantly less false positive diagnoses of 'veno-occlusive dysfunction' than intracavernou s injection of the combination papaverine/phentolamine. No difference was f ound in the quality of the arterial response. Based on this study we conclu de that sildenafil may replace ICI as mode of stimulation during PPDU.