Peter Thind

The Effect of Bilateral Pudendal Blockade on the Adjunctive Urethral Closure Forces in Healthy Females

The effect of bilateral pudendal blockade on the urethral pressure and power generation during coughing and pelvic floor squeezing was evaluated in 10 healthy women. The measurements were carried out at the bladder neck, in the high pressure zone, and distally in the urethra before and after blockade. Strong adjunctive closure forces were demonstrated all along the urethra. They were significantly reduced by pudendal blockade except at the bladder neck during coughing. The results indicate that the pudendal innervated striated muscles contribute significantly to the adjunctively acting closure forces all along the female urethra, including the bladder neck. Some passive pressure transmission to the bladder neck seems to take place during stress episodes following pudendal blockade, but whether it occurs in healthy females remain uncertain. The findings following pudendal blockade, corroborate with those in stress incontinent women, and thereby support the concept that striated muscle weakness is of pathophysiological significance in stress urinary incontinence.

The Effect of α-Adrenoceptor Stimulation and Blockade on the Static Urethral Sphincter Function in Healthy Females

The influence of noradrenaline and prazosin on the urethral closure function was evaluated in 10 healthy female volunteers. Measurements of pressure at varying cross sectional areas were carried out at the bladder neck, in the high pressure zone, and in the distal urethra. Prazosin reduced the static pressure, predominantly in the midportion of the urethra, whereas noradrenaline caused no significant pressure change. The urethral resistance to dilatation and the hysteresis were unaffected by the two agents. It is suggested that the response to prazosin is related to decreased activity of the urethral smooth as well as of the striated muscles, the latter as a result of a reduced somatomotor output from the central nervous system.

The Influence of β-Adrenoceptor and Muscarinic Receptor Agonists and Antagonists on the Static Urethral Closure Function in Healthy Females

The effects of terbutaline, propranolol, carbachol, and atropine on the static urethral closure function were investigated in 20 healthy women. Terbutaline caused a statistically reduction of the urethral pressure in the high pressure zone, but not at the bladder neck or in the distal urethra. The other drugs caused no significant pressure changes. None of the drugs used produced significant changes in the static viscoelastic properties, elastance, and hysteresis of the resting urethra. It is suggested that terbutaline partly reduces intraurethral pressure by reducing muscular tone in the rhabdosphincter and pelvic floor.

The Effect of Pharmacological Stimulation and Blockade of Autonomic Receptors on the Urethral Pressure and Power Generation During Coughing and Squeezing of the Pelvic Floor in Healthy Females

The effect of autonomic receptor agonists and antagonists on the urethral pressure and power generation during coughing and squeezing of the pelvic floor has been evaluated in 30 healthy females. The measurements were carried out at the bladder neck, in the high pressure zone, and distally in the urethra. The used drugs (noradrenaline, prazosin, terbutaline, propranolol, carbachol and atropine) caused no significant change in the pressure and power generation. The clinically relevant influence of drugs on the urethral closure function should be re-appraised when based on profilometry in the resting state. The results support that the effect of the autonomic nervous system on the urethral closure function is insignificant in healthy women. They furthermore indicate that investigations on the ability to secure continence cannot be based solely on resting pressure profilometry, but should be accomplished by measurements during stress episodes.

The rationale behind recommendations for follow-up after urinary diversion: An evidence-based approach

Departments of Urology, Haukeland University Hospital, Bergen, Norway, Aarhus University Hospital, Skejby Sygehus, Aarhus, Denmark, Sahlgrenska University Hospital, Göteborg, Sweden, Landspitali University Hospital, Reykjavik, Iceland, University Hospital, Lund University, Lund, Sweden, Oulu University Hospital, Oulu, Finland, Rikshospitalet University Hospital, Oslo, Norway, State University Hospital, Copenhagen, Denmark, and Kuopio University Hospital, Kuopio, Finland

Characterization of pressure changes in the lower urinary tract during coughing with special reference to the demands on the pressure recording equipment

The exact demands on urodynamic equipment for measurement of coughs and cough associated pressure changes in the lower urinary tract have been analyzed from high‐speed pressure recordings using a double microtip transducer and a storage oscilloscope. The equipment was tested in vitro by the step‐test method. The natural frequency response was 175.6 Hz and the rise‐time 2.5 ms, resulting in accurate measurements of frequencies up to about 60 Hz which is way above the clinically measured frequencies. Four men and 2 women, all of whom were healthy volunteers, were examined in the supine position with an empty bladder. Pressures were measured in the bladder and in the external sphincter zone of the urethra. The spectral power density of the bladder and urethral pressures were calculated by Fourier analysis. The pressure changes in the urethra were in all volunteers equal to or slower than in the bladder. The analysis of the spectral power density showed that 99% of the pressure changes could be recorded with an instrument capable of recording 9 Hz frequencies, i.e., with a sampling rate of 18 Hz or more.

How to measure urethral elastance in a simple way

SummaryThe elastance of a biological tube describes the resistance of the latter to dilatation. It is defined as dP/dV, where dP is the pressure increase caused by the volume increase dV. Elastance is the reciprocal of compliance. Elastance in the female urethra can be estimated from the slope of the regression line of related values of pressure and cross-sectional area. In the present study, urethral elastance was calculated by measurement of the related pressures and cross-sectional areas during stepwise dilatation by a balloon and by determination of the pressure at which inflow through side holes in catheters with increasing diameters began. There was no difference between the elastance values obtained by the two methods. Due to the linear correlation found between pressure and cross-sectional area we conclude that urethral elastance can be estimated from measurements of urethral pressure at two or more related cross-sectional areas by a simple technique using e.g., 8F, 14F, and 20F catheters.

Pressure response to rapid dilation of resting urethra in healthy women.

Rapid urethral dilations were performed by a balloon mounted on a double-tip transducer catheter for simultaneous measurement of pressure in urethra and bladder. The cross sectional area of the urethra was measured according to the field gradient principle. Pressure and cross sectional area were recorded synchronously. The response of the female urethra to rapid dilation is a typical stress relaxation effect with a pressure peak followed by a pressure decay over a few seconds. The peak pressure response represents the bladder pressure required in producing a corresponding urethral dilation by the ingression of urine. The increase in pressure response was statistically significant by increasing rate as well as size of dilation. The method enables experimental simulation of stress urinary incontinence in vivo which may bring further insight into the physiology of the urethral closure function and the pathophysiology of stress incontinence. For comparative studies rapid dilation should be performed under standardized circumstances.

INFLUENCE OF PUDENDAL NERVE BLOCKADE ON STRESS RELAXATION IN THE FEMALE URETHRA

The urethral pressure decay following a sudden and sustained dilatation corresponds to stress relaxation. Urethral stress relaxation can be described by the equation Pt = Pequ + Pαe‐t/τα + Pβe‐t/τβ, where Pt is the pressure at time t, Pequ is the equilibrium pressure after dilatation, Pα and Pβ are pressure decay, and τα and τβ are time constants. The time constants have previously proved independent of the way the dilatation is performed. The urethral stress relaxation obtained in 10 healthy women before and after pudendal nerve blockade was analysed by the mathematical model and the pressure parameters and time constants determined. The fast time constant, τβ, was reduced by the nerve blockade, whereas τα was unaffected, however, both Pα and Pβ were reduced. No single stress relaxation parameter can therefore be related to the muscle or the connective tissue components. The method may prove useful in the further evaluation of the closure function of the urethra with special reference to the pathophysiology of stress urinary incontinence.

Is Micturition Disorder a Pathogenic Factor in Acute Epididymitis? An Evaluation of Simultaneous Bladder Pressure and Urine Flow in Men with Previous Acute Epididymitis

We evaluated 22 men 22 to 70 years old with previous acute epididymitis by pressure-flow study 3 to 12 months after the inflammation had resolved. Nine healthy men 20 to 62 years old were evaluated as controls. The patients had no symptoms from the lower urinary tract except for 2 men with slight prostatism. The maximum intravesical and maximum voiding pressures were elevated significantly in the patients compared to the controls (p less than 0.05). In most patients and in all of the controls the maximum urinary flow rates were within the normal range according to age. Because of the frequency of high voiding pressures in patients with previous acute epididymitis, this condition may be a pathogenic factor by promoting urethrovasal reflux. The high voiding pressures may be transmitted to the proximal urethra or in cases of a narrow and rigid bladder neck they may produce increased turbulence in the urine stream.