Pharmacologic erection: time-dependent changes in the corporal environment.

Priapism is a persistent erection which fails to subside after climax and is accompanied by penile pain and tenderness. The most common form of priapism to confront contemporary urologists is persistence of erection following pharmacologic stimulation. We reviewed our experience over 18 months with initial diagnostic intracavernous challenges of prostaglandin E1. Three-hundred and sixty-six new impotence patients presented to our center and underwent PGE1/color duplex Doppler assessment; 14 patients developed persistent rigidity of two or more hours accompanied by penile discomfort. Each of these patients was successfully managed with penile aspiration and direct corporal instillation of the alpha-adrenergic agonist phenylephrine. The mean PGE1 dosage injected was 6 micrograms and mean duration of erection preceding aspiration 180 minutes. Penile blood gases were obtained from the initial aspirate in all cases. The duration of pharmacologic erections were correlated with the partial pressures of oxygen, carbon dioxide, bicarbonate and the pH using linear regression analysis. There was a clear trend towards deoxygenation, acidosis, and hypercarbia with prolonged erection (105-342 minutes). The relationship between duration of pharmacologic erection and acidosis/hypercarbia was highly significant.