Validation of a continuous penile blood-flow measurement by pulse-volume-plethysmography.

Today, in the assessment of cavernous artery blood-flow, the most commonly used technique is Doppler ultrasound velocimetry (continuous, pulsed, color-coded or power), which is often considered as the gold standard. Plethysmographic techniques and radioactive tracers have been widely used for the assessment of global penis flow variations but are not adequate for continuous blood-flow measurement. A new pulse-volume plethysmographic (PVP) device using a water-filled penile cuff was employed to assess continuous blood-flow measurement in the penis. Simultaneously Doppler velocity was recorded and served as a gold standard. A penile water-cuff is connected through a pressure tube to a three-way tap. The pulse-volume changes in the penile water-cuff are measured by means of a latex membrane placed over one of the three-way taps. The displacements of the latex are recorded by a photoplethysmograph. The third tap is connected to a 5 l perfusion bag placed 30 cm above the penis so as to maintain constant pressure in the whole device whatever the penis volume. Twenty-four volunteers were tested. The Doppler velocity signal and pulse volume of cavernous arteries were measured simultaneously after PGE1 intra-cavernous injection. Blood-flow variations were induced by increasing penis artery compression with a second penile water-cuff used as a tourniquet fitted onto the penis root, and the pressure of which could be modified by a water-filled syringe. The amplitude of the plethysmographic pulse-volume signal and the area under the Doppler velocity signal were correlated. The inter-patient (n=24) correlation ranged from 0.455 to 0.904, with a mean correlation of 0.704 and P<0.0001. PVP measurement by a water-filled cuff was validated by ultrasound velocimetry. This new continuous, non-invasive and easy-to-use technique enables physiological and physiopathological flow-measurement during sleep, under visual sexual stimulation (VSS), or following artificial erection. Simultaneous recording of penile blood-flow by PVP and intra-cavernous pressure (ICP) measured by a non-invasive device will provide fundamental inflow and outflow information in both physiological and pathophysiological conditions, and further enable venous leakage to be assessed by a mathematical model.

Clitoral blood flow increases following vaginal pressure stimulation.

The vascular responses of clitoral arteries to vaginal pressure stimulation in 10 volunteer women were evaluated by Doppler ultrasonography. Pressure stimulations (20-160 mm Hg) along the lower third of the vagina increased blood velocity and flow into clitoral arteries in 9 of the 10 women. The latency and duration of the Doppler responses ranged from 0.1 to 1.6 sec and from 3.2 to 9.5 sec, respectively, and the response was associated with a blood flow increase of 4 to 11 times the baseline prestimulation level. This response parallels that recorded in the cavernous arteries in men when a similar range of pressure stimulations are applied to the glans penis. Similar responses evoked in the male and female suggest a sexual synergy that may occur during intercourse in that such physiological responses and reflexes may be reciprocally reinforced.

[Supra-systolic elevation of the intra-cavernous pressure secondary to stimulation of the glans penis]. / Elévation suprasystolique de la pression intra-caverneuse secondaire à une stimulation du gland.

The role of the perineal muscles in human penile erections is still controversial. The authors investigated surface electromyographic activity of the ischiocavernous muscles together with intracavernous pressure recordings during pressure stimulations of the glans penis. Successive glans stimulations were associated with ischiocavernous muscle contractions and increases in intracavernous pressure reaching two- to fourfold the systolic blood pressure. High correlation coefficients were found between electromyographic and intracavernous pressure amplitudes. Voluntary contractions were accompanied by intracavernous pressure peaks of similar durations, and areas delineated by integrated electromyographic and intracavernous pressure curves showed very high correlation coefficients. Anaesthesia of the dorsal nerve resulted in dramatic reductions of muscle activity and intracavernous pressures in response to glans stimulation. These results suggest that the activity of the muscles in response to pressure stimulation of the glans penis is important to augment rigidity during vaginal penetration and intercourse due to their ability to increase intracavernous pressures.

[Considerable increase in the perineal arterial flow secondary to stimulation of the glans penis]. / Augmentation importante du débit artériel périnéal secondaire à une stimulation du gland.

The authors investigated the changes in human perineal blood flow by Doppler ultrasonography before, during, and after pressure stimulations (30,150 mm Hg) applied to the glans penis. We found a local increased blood flow response in 72% of 50 patients who consulted our center for erectile dysfunctions. Precise measurement analyses of 10 of these subjects allowed us to further characterize this response. Its latency ranged from 0.1 to 0.8 sec. and its duration from 4 to 13 sec. The blood flow increased up to 8 times the prestimulation level. This consistent increase in perineal blood flow showed much less variability than either the latency or duration of the response. The results of this study suggest that intravaginal pressures exerted on the glans penis during vaginal penetration and intercourse trigger an augmentation of blood flow into the corpora cavernosa. The reflex nature of this response is currently under investigation.

A new vacuum device as alternative treatment for impotence.

Vacuum erection devices are an acceptable alternative for the management of erectile dysfunction. The safety of such devices has been questioned because of their effects on penile blood flow. We report the use of Doppler ultrasonography to assess arterial flow and its value in ensuring long-term safety of a new external vacuum device. Sixteen patients were studied. At 3 months it was possible to confirm the efficacy and safety of the method and model in 14 patients, 12 of whom had a significant improvement in their sexual function. By 10 months, only 6 were continuing to use the device. Doppler sonography appears to be an effective technique for assessing penile blood flow during restriction from a vacuum device. The new vacuum device provides a satisfactory short-term alternative to other more invasive forms of therapy.

[The physiology of penile rigidity]. / Considérations sur la physiologie de la rigidité pénienne.

Penile tumescence and rigidity are considered to be a purely vascular process related to an increased inflow and a decreased outflow. This theory, which provides a satisfactory explanation for tumescence, is unable to explain the existence of high intracavernous pressures recorded both in animals and in man. Based on a hydrostatic model, the authors distinguish two phases involving different physiological mechanisms: an infrasystolic vascular phase and a suprasystolic muscular phase. During the vascular phase, the intracavernous pressure (ICP) can never exceed the systolic blood pressure. However, during the muscular phase, the ICP largely exceeds the systolic pressure, reaching values as high as 400 mmHg in man and 1,000 mmHg in animals. These variations in ICP can be explained by the contraction of perineal muscles, particularly the ischiocavernosus muscles. Various animal and human experiments are presented in support of this hypothesis. The pressure variations exerted on the glans during coitus by the perivaginal musculature are sufficient to induce reflex contractions of the ischiocavernosus muscles, promoting penile rigidity.

Validation of a non-invasive device to measure intracavernous pressure as an index of penile rigidity.

Many authors agree with the importance of developing devices to measure penile rigidity. The devices that have been developed over recent years have defined penile rigidity in terms of stiffness. Penile stiffness, however, is believed to result from an increase in intracavernous pressure. The device presented here was therefore designed to estimate intracavernous pressure, rather than penile stiffness, as an index of penile rigidity. Validation of the penile cuff device was achieved by simultaneously recording penile cuff pressure and intracavernous pressure on patients undergoing artificial erections. The results showed a linear relationship and highly positive correlation coefficients between the 2 measures. The results demonstrate that the penile cuff may be used to estimate intracavernous pressure as an index of penile rigidity. The findings are discussed in terms of the possible applications of the cuff as a clinical tool to measure both penile tumescence and penile rigidity.

Bulbocavernosus reflex: its validity as a diagnostic test of neurogenic impotence.

Measurement of the bulbocavernosus reflex is used widely to diagnose underlying neurogenic disorders in erectile dysfunction. A prolonged bulbocavernosus reflex latency (that is more than 45 msec.) or the absence of a reflex response of the bulbocavernosus muscles during electrical stimulation of the glans penis is considered a sign of neurological disease. Since only a few experimental studies have been performed in man related to the neurophysiological mechanism of erection, and since the results of these studies were contradictory the diagnostic validity of bulbocavernosus reflex measurement was reassessed. We determine whether men with abnormal bulbocavernosus reflex latencies have concomitant organic erectile dysfunction as confirmed by nocturnal plethysmographic and rigidity recordings. The bulbocavernosus reflex was recorded in 90 subjects and 19 had abnormal bulbocavernosus reflex latencies. Of these 19 subjects 8 had normal nocturnal erections, thus, confirming a diagnosis of psychogenic impotence. These results cast some doubts on the validity of bulbocavernosus reflex measurement for the diagnosis of organic erectile dysfunction due to a neurological disease.

Reflex contractions of the ischiocavernosus muscles following electrical and pressure stimulations.

In a previous study, we have demonstrated that voluntary muscular contractions of the ischiocavernosus muscles (IC) correlate with changes in intracavernous pressure and, therefore, with penile rigidity. The purpose of our current research project was to verify whether reflex contractions of the IC muscles exist and under what conditions. Our results confirm that reflex contractions occur following electrical or pressure stimulations. Following electrical stimulation, the mean latency of the reflex contractions was 67.5 ms for the IC muscles and 34.9 ms for the bulbocavernosus muscles (BC). Following pressure stimulation, the pressure threshold necessary to elicit contractions of the IC muscles varied between 18.2 mm. Hg and 34.8 mm. Hg. We also observed that pressure variation (increase and decrease) rather than a relatively constant pressure is necessary to produce this reflex response. We interpret these results to suggest that pressure stimulations on the glans penis during coitus contribute to the erectile process and, specifically, to the increase in intracavernous pressure. These findings suggest the possibility of a physiotherapeutic management for patients with penile rigidity problems.

[Several techniques proposed for the differential diagnosis of diabetic impotence]. / Le point sur les diverses techniques proposées pour le diagnostic différentiel de l'impuissance diabétique.

The measurements of changes in penile circumference during nocturnal erection is commonly used to differentiate between organic and psychogenic impotence. Unfortunately, this measuring technique do not record variations in penile rigidity which may be insufficient to achieve coitus despite a normal circumference. We carried out a study with a penile cuff to measure penile rigidity. The validation of this penile cuff as a measurement device of penile rigidity permits us to determine the criteria of normality of penile rigidity and, subsequently, to differentiate more accurately between organic and psychogenic dysfunctions. Measurement of the bulbocavernous reflex (BCR) is widely used to diagnose underlying neurologic disorders in erectile dysfunctions. A prolonged BCR latency, more than 45 ms, or absence of a reflex response of the BC muscles during electrical stimulation of the glans penis, is considered like a sign of neurologic disease. We recorded the BCR in 90 subjects. Nineteen had abnormal BCR latencies. Furthermore, eight of these 19 subjects had normal nocturnal erections, thus confirming the diagnosis of psychogenic impotence. These results cast doubt on the validity of BCR measurements of the diagnosis of organic erectile dysfunction due to a neurologic disease. We recorded the BCR in 90 subjects. Nineteen had abnormal BCR latencies. Furthermore, eight of these 19 subjects had normal nocturnal erections, thus confirming the diagnosis of psychogenic impotence. These results cast doubt on the validity of BCR measurements for the diagnosis of organic erectile dysfunction due to a neurologic disease.

Relationship between perineal muscle contractions, penile tumescence, and penile rigidity during nocturnal erections.

The mechanism of penile erection and erectile dysfunction is still unclear and widely debated. The role of the perineal muscles in the erectile process, especially in changes in intracavernous pressure, is increasingly being studied on the hypothesis that perineal muscular contractions are essential to full penile rigidity. In a previous investigation we studied the correlation between voluntary perineal muscle contractions and intracavernous pressure during artificially induced erections. The purpose of the current study was to examine whether under normal conditions of nocturnal erection a similar relationship exists between the electromyographic activities of perineal muscles and changes in penile rigidity. Nocturnal penile recordings were made of seven volunteers with psychogenic erectile dysfunctions. During nocturnal erections simultaneous computerized recordings were made of penile tumescence, penile rigidity, and electromyographic activities of perineal muscles. The peaks for the three variables were reached simultaneously. The results of this study suggest the existence of two different physiologic phases: a vascular phase and a muscular phase. Furthermore, in cases of dysfunctions, specific diagnostic assessment and therapeutic management will be required for both penile tumescence and penile rigidity.

Correlation between intracavernous pressure and contraction of the ischiocavernosus muscle in man.

An artificial erection was induced in nine patients consulting for erectile dysfunction. Changes in the intracavernous pressure (ICP) and in the integrated EMG of the ischiocavernosus muscle were recorded during voluntary muscular contractions. During such contractions elevations in ICP, varying between 100 and 525 mm. Hg, were recorded. Changes in ICP were always in phase with changes in the integrated electromyogram (EMG) of the ischiocavernosus muscle, and correlations between the duration of changes showed an almost perfect linear relationship between both physiological events. Correlations between maximum changes in ICP and integrated EMG generally showed a positive relationship between both measures. Results are interpreted to suggest involvement of the ischiocavernosus muscle in the process of penile rigidity.

Sexual activity and sleep in humans.

Polysomnographic recordings were obtained in 10 subjects (5 men and 5 women) for three conditions: following masturbation with orgasm, following masturbation without orgasm, and after reading neutral material. The analysis of several sleep parameters did not reveal any effect of masturbation on sleep. These results suggest that physiological changes that occur during masturbation, with or without orgasm, have no major effect on sleep organization. Other factors associated with sexual activity and potentially responsible for sleepiness after orgasm are discussed, and further strategies to study the interrelationship of sexual activity and sleep are proposed.