Biomedical subjects

Stefan De Wachter

Publications and source records attributed to Stefan De Wachter.

11 recordsLinked to original sources

PubMed2006

Does the cystometric filling rate affect the afferent bladder response pattern? A study on single fibre pelvic nerve afferents in the rat urinary bladder.

AIMS: To study the effect of physiological and supraphysiological filling rates on the response pattern of single fibre pelvic nerve afferents of the rat urinary bladder. MATERIALS AND METHODS: A total of 37 single afferent bladder units were identified electrophysiologically and their mechanosensitive properties studied. Afferent activity of 13 units was studied at filling rates of 40 and 200 microl/min. Afferent activity of the other units was studied at 200 and 400 microl/min. RESULTS: At the physiological filling rate of 40 microl/min two clearly different types of response pattern were noted. However, at higher supraphysiological filling rates, all units exhibited nearly the same pattern. The difference in mechanosensitive properties of the units that showed a change in response pattern at the supraphysiological filling rate, was characterized by a decrease in pressure at which afferent firing rate peaked. For all units it was found that an increase in filling rate induced an increase in the activation pressure threshold for afferent units, whereas the afferent firing rate at all pressures decreased. CONCLUSIONS: In rats supraphysiological filling rates delay afferent activation, lower afferent firing activity and even change the characteristics of some afferents completely. These data may elucidate some of the differences between ambulatory and conventional urodynamics observed in man.

Animals↗

PubMed2006

Systemic oxybutynin decreases afferent activity of the pelvic nerve of the rat: new insights into the working mechanism of antimuscarinics.

AIMS: In a rat model, intravesical oxybutynin was recently shown to suppress pelvic afferent nerves. This study evaluates if a similar effect exists after systemic administration of oxybutynin. METHODS: Twenty-four single afferent bladder nerves were identified in 15 rats. Based on their conduction velocities they were grouped as C or Adelta fibers. Bladder filling parameters and afferent nerve spike rate were simultaneously recorded 30 min before administration of saline (nine fibers) or oxybutynin (15 fibers, 1 mg/kg), and again 30, 60, 90, 120, and 150 min after systemic saline or drug administration. RESULTS: No change in C or Adelta afferent spike rate was observed after saline injection (P > 0.90). In the study group, a decrease in afferent activity was noted after systemic administration of oxybutynin for C fibers, which were statistically significant 90 (P < 0.004) and 120 min (P < 0.028) after drug delivery. After 150 min, the spike rate was still lower compared to the baseline filling, without reaching the level of significance (P > 0.09). For the Adelta fibers the decrease in afferent spike rate was already significant at 30 min (P < 0.005) and remained significant during all subsequent fillings (P < 0.012). To avoid a possible confounding influence of the bladder compliance, which increased significantly after injection of oxybutynin (P < 0.011), afferent activity during bladder filling was recalculated. Normalized afferent sensitivity of C and Adelta fibers decreased significantly after injection of oxybutynin. This means that the decrease in afferent spike rate is not the result of an increased compliance. CONCLUSIONS: The findings of this study strongly suggest that oxybutynin directly or indirectly influences bladder sensory nerves, inhibiting the afferent part of the micturition reflex.

Animals↗

PubMed2006

Healthy, middle-aged, history-free, continent women--do they strain to void?

PURPOSE: We evaluated to what extent abdominal straining is used for voiding in an asymptomatic, continent, healthy, middle-aged female population. MATERIALS AND METHODS: A total of 32 women (mean age 49 +/- 6 years old) could be prospectively included. Technical investigations consisted of flowmetry, pressure flowmetry with EMG and electrosensation evaluation. Some data were compared with those of stress incontinent women investigated prospectively in the same way. RESULTS: There were 4 women who were excluded from analysis because of abnormal sensory evaluation. The symptom-free participants voided with low detrusor pressure, a high flow rate and no residual. A large segment (42%) used additional abdominal straining to void on cystometry and reported that such straining was their usual habit for voiding at home. Straining was seen as frequent in women with stress incontinence. However, significantly more women with stress incontinence used straining without detrusor contraction. CONCLUSIONS: These healthy middle-aged women without a history of pelvic surgery, or symptoms or signs of urological, anorectal or gynecological problems, voided with a mean Pdetmax of 25 cm H(2)O, mean Qmax of 29 ml per second, and the majority without residual. Many of them strained during detrusor contraction and this had not led to the development of signs or symptoms. The way straining is done may make the difference in that during reflex bladder contraction and urethral relaxation, additional straining may have little negative effect. If straining is used to void without the initiation of the micturition reflex, voiding dysfunction and incontinence might develop more easily.

Adult↗

PubMed2005

Current perception thresholds in the lower urinary tract: Sine- and square-wave currents studied in young healthy volunteers.

AIMS: To establish normative current perception threshold (CPT) values with neuroselective sine-wave current in the lower urinary tract and to compare these values with square-wave current CPTs. MATERIALS AND METHODS: 10 female and 8 male healthy volunteers were used for this study. A filling cystometry was performed and CPTs were determined with square-wave current at a frequency of 2.5 Hz and with neuroselective sine-wave current at 5 (C-fiber), 250 (Adelta-fiber), and 2000 Hz (Abeta-fiber) in the bladder, the posterior, and the distal urethra. RESULTS: Bladder CPTs were significantly higher compared with CPTs in the posterior urethra (P < 0.028) and in the distal urethra (P < 0.002) with all three sine-wave frequencies. No significant difference was found with any sine-wave frequency between the posterior and distal urethra (P > 0.30). Using square-wave pulses at 2.5 Hz, CPTs decreased towards the distal urethra, with a significant difference between the three stimulation sites (P < 0.0001). At all sites tested, the CPT's determined with sine-wave current at 2000 Hz were significantly higher than those at 250 Hz (P < 0.002) and 5 Hz (P < 0.001). No significant difference was found between 5 Hz and 250 Hz at any site in the LUT (P > 0.50). At all sites, CPTs determined with square-wave pulses at 2.5 Hz were significantly higher than those determined with sine-wave current at all frequencies (P < 0.001). CPTs determined with all sine-wave currents were not correlated with CPTs using square-wave pulses. There was no correlation between the volumes at which sensation of filling occurred and the CPTs. CONCLUSIONS: We described normative values in young healthy volunteers at three sites in the LUT using sine-wave current. Although this type of current is said to be neuroselctive, this needs to be confirmed. Stimulation with sine-wave current is different and might be more physiologic compared to square-wave stimulation. Our data show that sine-wave current stimulation at 5 Hz, 250 Hz, and 2000 Hz can probably not be used as a semi-objective measurement of the sensation of bladder filling because no correlation was found between CPTs and the cystometeric sensation of filling.

Adult↗

PubMed2004

A normal flow pattern in women does not exclude voiding pathology.

It is a widespread assumption that normal micturition behaviour is reflected in a normal flow pattern. This would also mean that a normal flow curve would correspond with normal voiding and would even permit to exclude voiding difficulties. In our study we investigated the value of a normal flow pattern in four different groups: stress incontinent women, women with bladder overactivity, healthy middle-aged volunteers and healthy students. These women voided with a bell-shaped flow curve on pressure flow in 50, 65, 57 and 50%, respectively. Women who strained to void, a major component of dysfunctional voiding, managed to void a bell-shaped flow curve in 46, 60, 70 and 100%, respectively. Our study demonstrates that a "normal" bell-shaped flow curve does not exclude voiding dysfunction in women.

Adult↗

PubMed2004

Detrusor overactivity. Does it represent a difference if patients feel the involuntary contractions?

PURPOSE: We evaluated the differences between patients with overactive bladder (OAB) who felt involuntary detrusor contractions during cystometry (detrusor overactivity [DO]) and those who did not feel them. MATERIALS AND METHODS: We prospectively studied 45 patients with symptoms of nonneurogenic, nonobstructed overactive bladder and with DO on cystometry. All patients underwent videourodynamics, the ice water test and electrical perception threshold determination. Continence, urodynamic parameters, data from specific sensory evaluation and outcome of drug treatment were examined. RESULTS: Almost half of our patients did feel the contractions of DO and half did not. The groups differed significantly. Those without DO sensation were more frequently incontinent, had more involuntary detrusor contractions and these occurred earlier during bladder filling. They had involuntary start of voiding more frequently, more pathological sensation of bladder filling and lower electrical sensory thresholds. The results of drug treatment were better in the group who felt DO. CONCLUSIONS: Contractions of DO are felt by some of the patients and they differ from those patients who do not feel such contractions. It is likely that this finding reflects the existence of different OAB conditions with a different neuropathological cause and a different treatment outcome. Therefore, we suggest that specific tests for the evaluation of sensation in the lower urinary tract should be part of the diagnosis of patients with DO and symptoms of OAB.

Adult↗

PubMed2003

Quest for standardisation of electrical sensory testing in the lower urinary tract: the influence of technique related factors on bladder electrical thresholds.

AIMS: The aim of this study is to determine the influence of technique-related factors on bladder electrical thresholds in order to establish more standardisation in electrical sensory testing in the lower urinary tract (LUT). METHODS: In 51 young healthy volunteers, electrical thresholds were determined in the bladder by using different techniques described in the literature. Within an individual, thresholds were repeatedly determined in the bladder while varying the position of the stimulating electrodes and the intravesical volume. RESULTS: The height of bladder electrical thresholds is influenced by the position of the stimulating electrodes and the volume of the intravesical fluid at the time of the examination. By filling the bladder, the sensitivity of the bladder toward electrical stimulation can be increased. CONCLUSIONS: Although the techniques to test electrical sensitivity have already proven to be a valuable tool in diagnosing the presence of neuropathy in the LUT, its full scope can only be evaluated after standardisation. Therefore, it is proposed that the position of the stimulating electrodes and the bladder volume at the time of the examination should be outlined in studies and standardised.

Adolescent↗

PubMed2003

Frequency-volume charts: a tool to evaluate bladder sensation.

AIMS: Bladder sensation is routinely evaluated by cystometric bladder filling and electrical stimulation. These methods require catheterization and stimulate the bladder artificially. In this study, we evaluated whether frequency-volume charts can be used as a non-invasive tool to study bladder sensation during normal daily life. Furthermore the agreement between sensory data obtained from frequency-volume charts and conventional cystometric bladder filling is studied. MATERIALS AND METHODS: Fifteen healthy female students filled out frequency-volume charts at home and scored the grade of perception of bladder fullness at each micturition. They also measured the volume of three voidings after postponing micturition as long as possible. Sensation of bladder filling was finally evaluated during cystometry. RESULTS: On frequency-volume charts, 65% of all voidings was made without desire to void, only 9.5% was with strong desire. Urgent desire to void was not reported except after voluntarily postponing micturition. Higher grades of perception of fullness were associated with significantly higher voided volumes. Mean volumes for the different sensations of fullness on the charts were not significantly different from volumes at different sensations reported during cystometry. CONCLUSIONS: In conclusion, bladder sensation during daily life can be evaluated by scoring the grade of perception of fullness on frequency-volume charts. During life voiding usually occurs without desire to void. The voided volumes at different sensations of fullness are comparable to the volumes at different sensations of filling during cystometry. Therefore, frequency-volume charts with evaluation of perception of fullness may provide an initial non-invasive tool to study bladder sensation.

Adolescent↗

PubMed2003

The basics behind bladder pain: a review of data on lower urinary tract sensations.

Interstitial cystitis is a syndrome consisting of frequency, urgency, and bladder pain that increases with bladder filling and improves temporarily after voiding. The exact cause or causes are not as yet fully understood. This leads to uncertainty in diagnosis and treatment. There is need for more knowledge, and to acquire this for more research. The fact that the condition causes pain, a pathologic stimulation of sensory fibres, makes understanding the basic sensory mechanisms in the lower urinary tract in normal and pathologic conditions mandatory. In this article we review the data on bladder sensation from the last 25 years and the possible relation with painful bladder syndrome.

Afferent Pathways↗

PubMed2003

Intravesical oxybutynin: a local anesthetic effect on bladder C afferents.

PURPOSE: Intravesical oxybutynin is used to control bladder overactivity in patients who are refractory to or cannot tolerate oxybutynin given orally. Although it is clinically effective, the mode of action of intravesical oxybutynin remains unclear. We tested the influence of intravesical oxybutynin on single fiber pelvic nerve afferents from the rat bladder. MATERIALS AND METHODS: A total of 15 single afferent bladder units were identified. Based on conduction velocity they were grouped as Adelta or C fibers. The effect of repeat bladder filling was studied on the mechanosensitive properties of these units. Oxybutynin was than instilled and left in the bladder for 15 minutes. Unitary afferent activity was again analyzed 15, 60 and 90 minutes after the drug was removed. RESULTS: Repeat bladder filling did not change nerve activity in Adelta or C fibers. At 15 minutes after oxybutynin was washed out of the bladder C fiber afferents responded significantly less to intravesical pressure and volume compared with control filling. At 60 minutes C fibers partly regained mechanosensivity. After 90 minutes sensitivity still increased without achieving the response level before oxybutynin. No significant changes were noted in Adelta fibers during repeat bladder filling or after oxybutynin instillation. CONCLUSIONS: In this study we showed that intravesical oxybutynin has a direct anesthetic effect within the bladder wall. It temporarily desensitizes C fiber afferents, which could explain its clinical benefits in decreasing symptoms of bladder overactivity. No measurable effect was found on Adelta fibers.

Administration, Intravesical↗

PubMed2003

Impact of rectal distention on the results of evaluations of lower urinary tract sensation.

PURPOSE: To our knowledge no systematic studies have been performed in humans to test the interaction of normal bladder and rectal sensory function. However, symptoms affecting the different pelvic viscera often coexist. MATERIALS AND METHODS: In 15 healthy female volunteers sensations of bladder filling were evaluated during 2 consecutive cystometric studies, including 1 with an empty rectum and 1 with a full rectum. Similarly the electrical perception threshold was determined in the bladder when the rectum was empty and again when the rectum was full. RESULTS: Rectal distention did not change bladder compliance during filling. When the rectum was distended, sensations of bladder filling were reported at smaller volumes. On the other hand, electrical perception thresholds in the bladder were higher when the rectum was full. CONCLUSIONS: The state of the rectum significantly influences the sensations of bladder filling and electrical bladder stimulation. These results show that before sensory testing of the bladder rectal fullness should be examined and if necessary the rectum should be emptied. The different effect of rectal distention on filling and electrical sensations represents an additional argument for different innervation of the 2 sensations in the lower urinary tract.

Adolescent↗