Intracavernosal Pressure Monitoring Research Articles

Laser oximetry: A novel noninvasive method to determine changes in penile hemodynamics in an anesthetized rabbit model.

This study was designed to determine the utility and validity of laser oximetry in measuring changes in penile hemodynamics. Anesthetized male New Zealand White Rabbits were divided into 2 groups, and penile hemodynamics were assessed by either laser oximetry (oxyhemoglobin, deoxyhemoglobin concentration, and oxygen saturation) or intracavernosal pressure (ICP) monitoring during penile erection induced by pelvic nerve stimulation (PNS) or intracavernosal administration of phentolamine, nitroprusside, papaverine, or sildenafil. PNS caused significant frequency-dependent increases in penile ICP. PNS also caused significant increases in penile tissue oxyhemoglobin concentrations and tissue oxygen saturation in a frequency-dependent manner. The changes in oxyhemoglobin concentrations and oxygen saturation correlated with frequency-dependent increases in ICP. Intracavernosal vasoactive drug administration produced significant increases in ICP, tissue oxyhemoglobin concentration, oxygen saturation, and duration of response as a function of increasing drug concentration. Laser oximetry permits reproducible and valid assessment of changes in penile hemodynamics comparable to conventional ICP measurements. Thus, we consider laser oximetry a reliable technique in evaluating penile hemodynamics. Its sensitivity in detecting small changes in oxyhemoglobin concentration and its noninvasive nature make it advantageous over invasive methods such as ICP monitoring and laser Doppler flowmetry.

Intracavernosal pressure monitoring in mice: responses to electrical stimulation of the cavernous nerve and to intracavernosal drug administration

Intracavernosal pressure monitoring in mice: responses to electrical stimulation of the cavernous nerve and to intracavernosal drug administration

Intracavernosal pressure monitoring in mice: responses to electrical stimulation of the cavernous nerve and to intracavernosal drug administration.

With the development of transgenic mice to evaluate mechanisms of erectile function, it appears particularly advantageous to develop a standardized mouse model of penile erection. The purpose of the study reported here was to evaluate the novel application of intracavernosal pressure (ICP) monitoring in the mouse during electrophysiologic and pharmacologic induction of penile erection. In anesthetized adult male mice, the cavernous nerves (CN) were isolated unilaterally, and the corpora cavernosa were exposed. A 24-gauge angiocath (intravenous catheter) was inserted into the right corpus cavernosum to monitor the ICP, and a 30.5-gauge needle was inserted into the left corpus cavernosum for intracavernosal drug administration. ICP was recorded during CN-stimulated or pharmacostimulated erections. Electrical stimulation of the CN significantly increased the ICP (from 10.09 +/- 2.01 to 34.62 +/- 2.71 mm Hg, P < .05), which then returned to baseline pressure after termination of the electrical stimulation. Pretreatment with intracavernosal administration of the nitric oxide synthase inhibitor, nitro-L-arginine methyl ester (0.1 mg), inhibited the electrical stimulation-induced changes in ICP (7.17 +/- 1.46 vs 10.38 +/- 2.17 mm Hg, not significant [NS]). Also, intracavernosal administration of papaverine (0.4 mg) produced a significant increase in ICP (from 8.51 +/- 0.69 to 26.37 +/- 5.7 mm Hg, P < .05). We concluded that this technique might be applied to perform quantitative erection physiologic experiments with the mouse as an economical and experimentally advantageous animal model, particularly with the development of transgenic mice to evaluate mechanisms of erectile function.

Intraoperative electrical stimulation of cavernosal nerves with monitoring of intracorporeal pressure in patients undergoing nerve sparing radical prostatectomy.

To explore the utility of intraoperative cavernosal nerve stimulation in facilitating atraumatic nerve dissection during radical prostatectomy, and thus help predict postoperative erectile function. Fourteen patients (aged 51-72 years) underwent nerve-sparing radical retropubic prostatectomy (NSRRP); 10 were potent before surgery (group 1), and four had erectile dysfunction (group 2). A multi-acquisition system (MacLab/8e) with a Macintosh computer was used for real-time display and recording of intracavernosal pressure (ICP) during surgery. Nerves were stimulated with a bipolar probe (monophasic rectangular pulses, 10 mA, 20 Hz, 0.22 s) before and after removal of the gland. The follow-up consisted of interviews with patients and their partners' 12-18 months after treatment. The mean (sem) basal ICP of 8. 0 (2.0) cmH2O remained unchanged during nerve dissection. The mean increase in ICP during electrical stimulation was >50 cmH2O in seven potent patients (group 1) and was sustained as long as the nerve was stimulated. Postoperatively, these seven patients reported erections sufficient for sexual intercourse. However, the three remaining patients in group 1 had pressure rises of <30 cmH2O, of whom two reported partial erections and one reported total impotence postoperatively. The recovery time for erectile function was 6-12 months after surgery. Two patients from group 2 had transient increases in ICP to <40 cmH2O; one had an increase to 20 cmH2O and one had no response at all. All four patients remained totally impotent postoperatively. There were no complications. Intraoperative electrical stimulation of the cavernosal nerves with ICP monitoring before and after NSRRP is a safe and reliable method for documenting nerve continuity and its functional status. Patients who have normal preoperative erectile function and show an adequate rise in ICP upon electrical nerve stimulation during NSRRP will almost certainly be potent after surgery. This tool may be used to facilitate atraumatic nerve dissection during NSRRP.

Use of radioactive tracers in the evaluation of penile hemodynamics: history, methodology and measurements.

Radionuclide tracer techniques are intimately associated with some of the early ground-breaking investigations in erectile dysfunction and have evolved along with the field. At the present time, the various investigations can be grouped into four categories: labeled blood-pool; tracer washout; tracer washin and combined blood-pool/tracer and tracer washout examinations. Blood pool studies are most useful in assessing the integrity of arterial inflow, but may also be used to generate indices of venous leak. A non-imaging version of the blood-pool test may represent a simple and cost-effective alternative. Washout of intracavernosal xenon during erection seems the most rigorous method of testing venous integrity. Washout using 99mTc-labeled substances may emerge as a convenient alternative to the more technically difficult xenon examinations. Dual-isotope blood pool and washout examinations, though complicated, represent an ideal method of analyzing penile hemodynamics, with potential to contribute significantly to the understanding of penile physiology. Development of improved pharmacologic stimuli and augmentation of testing protocols by intracavernosal pressure monitoring may further improve the utility of quantitative and physiologic nuclear medicine examinations in erectile dysfunction.