title: Objective measurement of the effectiveness, therapeutic success and dynamic mechanisms of the vacuum device.
abstract: OBJECTIVE
  To determine the efficacy and possible beneficial effects of the Catalyst vacuum device (VD) in the treatment of impotence, the ischaemic state of the penis after application of a constriction ring and the origin of the blood in the corpus cavernosum after application of the VD.
  
  
  METHODS
  Thirty men (mean age 62 years; range 46-76) suffering from erectile dysfunction were selected for the trial after using the VD for 2 weeks at home. Changes in penile tumescence and rigidity before, during and after the VD were assessed using the Rigiscan monitor. Blood gas analysis (BGA) was performed in selected patients whilst using the VD, allowing calculation of the proportional contribution of venous and arterial blood to the increase in penile volume. The efficacy of the VD was also assessed by questionnaires completed before treatment and at the 6 month follow-up.
  
  
  RESULTS
  Four patients were lost to follow-up but the 26 impotent men who used the VD for 6 months were able to have sexual intercourse after using the VD. The average rigidity measured at the base and tip of the penis after application of the VD was > 80%. The duration and extent of nocturnal penile tumescence and rigidity at the start and the end of the study improved, although only one variable increased significantly. Patients reporting spontaneous morning erections showed significant improvements in total erection-time, erection-phase and plateau-phase duration, effective rigidity and tumescence increase. BGA determined 30 min after applying a constriction ring showed ischaemia of the penile blood and the mean contribution of arterial and venous blood to penile blood volume was by 58 and 42%, respectively.
  
  
  CONCLUSIONS
  The efficacy of the Catalyst vacuum device was objectively determined and the quality of the nocturnal erections improved in some patients. After application of a constriction ring an ischaemia of the penis developed. In contrast to previous reports, the increased penis volume during the application of the VD is caused not only by arterial inflow but also by venous backflow.
authors.affiliation: Clinic of Urology, RWTH Aachen, Germany.
authors.forename: R J
authors.initials: RJ
authors.lastname: Bosshardt
authors.forename: R
authors.initials: R
authors.lastname: Farwerk
authors.forename: R
authors.initials: R
authors.lastname: Sikora
authors.forename: M
authors.initials: M
authors.lastname: Sohn
authors.forename: G
authors.initials: G
authors.lastname: Jakse
mesh_terms: D000368:Aged; D001785:Blood Gas Monitoring, Transcutaneous; D007172:Erectile Dysfunction / Q000097:blood / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D007511:Ischemia / Q000097:blood / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010410:Penile Erection; D010413:Penis / Q000098:blood supply; D011446:Prospective Studies; D016896:Treatment Outcome; D014572:Urology / Q000379:methods*; D014618:Vacuum