Comparison of repeatability of non-invasive and invasive urodynamics

Assessment of BPH/BOO

The assessment of men with bladder outflow obstruction relies on an adequate history and examination. Uroflowmetry and post-void residue estimation are very revealing and may be sufficient in the majority of men. The prostate-specific antigen test may be used to select men who are at a high risk of progression. In specific situations, cystometry may be required. We discuss the use of cystometry and the newer less-invasive methods of assessment that have emerged over the last few years, including ultrasound estimation of intravesical prostatic protrusion, prostatic urethra angle, detrusor wall thickness, ultrasound-estimated bladder weight, near-infrared spectroscopy and the condom catheter and penile cuff tests. Although these techniques show promise, they still require further modifications, standardization and testing in larger populations. In addition, they should be used in men where only specific questions need to be answered.

Development and application of the condom catheter method for non-invasive measurement of bladder pressure

Objectives:

A non-invasive method to measure the bladder pressure in males using a condom catheter has been developed. The measurement technique, its validation and limitations, a diagnostic nomogram to non-invasively diagnose bladder outlet obstruction (BOO), and results of large-scale application are discussed.

Methods:

Modified incontinence condoms are attached to the penis. During voiding the flow of urine is mechanically interrupted. The subsequent maximum pressure in the condom reflects the isovolumetric bladder pressure. The method was validated in a group of 46 patients with lower urinary tract symptoms who were simultaneously studied invasively and non-invasively. Subsequently it was applied in a non-invasive epidemiological study in 1020 healthy males.

Results:

The reproducibility of the measured isovolumetric bladder pressure is comparable to that of conventional pressure-flow parameters. The measured pressure can be used to diagnose bladder outlet obstruction with a diagnostic accuracy (Area Under receiver operator characteristic curve) of 0.98, which compares most favorably with the area under the curve of 0.79 of Q_max in the same population. During condom catheter measurements, both the involuntary interruption of voiding and the forced diuresis increase post-void residual volume. This increase does not affect the accuracy of the pressure measurements.

Conclusions:

We conclude that in males bladder pressure can successfully be measured non-invasively using the condom catheter method. By combining the measured volumetric bladder pressure with a separately measured free flow rate, BOO can non-invasively and accurately be diagnosed.

Perineal sound recording for diagnosis of bladder outlet obstruction

Objectives:

Elderly men are prone to developing lower urinary tract symptoms (LUTS) possibly caused by bladder outlet obstruction (BOO). The most frequently used method to diagnose this condition is an invasive and time-consuming pressure-flow study. We are developing a novel non-invasive method to diagnose BOO in men with LUTS based on perineal sound recording.

Methods:

A biophysical model urethra was made from polyvinyl alcohol (PVA) cryogel with viscoelastic properties comparable to those of the male pig urethra. To this model different degrees of obstruction were applied and sound was recorded at different positions downstream of the obstruction. In a study in 16 healthy male volunteers the variability and repeatability of perineal sound recording was tested.

Results:

In the model three parameters, derived from the frequency spectrum of the recorded sound (i.e., weighted average frequency, standard deviation and skewness) are uniquely related to the degree of obstruction (linear regression, P<0.001). The variability of perineal sound recording in healthy male volunteers was found to be smaller within volunteers than between volunteers (Kruskal-Wallis, P<0.001) and the repeatability was comparable to that of the maximum flow rate.

Conclusions:

We conclude that perineal sound recordings are significantly different between volunteers. In combination with the unique relations found in the model-experiments these results increase the probability that perineal sound recording can be used as a simple and cheap non-invasive method to diagnose BOO. Clinical testing of this method is therefore strongly indicated.

Variability and repeatability of perineal sound recording in a population of healthy male volunteers

OBJECTIVES

In a population of 16 healthy male volunteers we studied the variability and repeatability of perineal sound recording as a non-invasive method for diagnosing bladder outlet obstruction.

MATERIALS AND METHODS

The volunteers had a flat age-distribution (22-62 years), a median IPSS-score of 1 (range: 0-18) and voided at least 10 times. From each perineal sound recording the frequency spectrum was calculated and characterized by its weighted average frequency, standard deviation and skewness. We assessed the variability of these parameters using the Kruskal-Wallis test, differences between volunteers using Dunn's test and the repeatability by the normalized standard deviation of the differences between pairs of recordings in each volunteer.

RESULTS

For each parameter the variability within volunteers was significantly smaller than the variability between volunteers (Kruskal-Wallis, P < 0.05). For each parameter more than one volunteer was significantly different from three or more volunteers (Dunn's test, P < 0.05). The repeatability of each parameter was comparable to that of the maximum flow rate.

CONCLUSION

Perineal sound recording gives repeatable results, which are significantly different between volunteers. In combination with the earlier published results from model-experiments the present results increase the probability that perineal sound recording can be used as a very simple and cheap method to non-invasively diagnose BOO. Clinical testing of this method is therefore strongly indicated.

Simultaneous registration of intraabdominal and intravesical pressures during cystometry in conscious rats—Effects of bladder outlet obstruction and intravesical PGE2

AIMS

A method was developed and evaluated to simultaneously register intraabdominal pressure (IAP) and intravesical pressure (IVP) during cystometry in conscious rats. In addition, IAP and IVP were recorded in rats with experimental detrusor overactivity (DO).

METHODS

Sprague Dawley rats (n = 24) were used. Six female rats were subjected to partial bladder outlet obstruction for 2 weeks. A catheter was implanted into the bladder to record the IVP, and a balloon-fitted catheter was positioned in the abdominal cavity to record the IAP. PGE(2) was given intravesically to induce DO. Detrusor pressure (DP) was defined as the IVP corrected for IAP.

RESULTS

Recorded as increases in IAP, all rats of both sexes exhibited abdominal straining during every void. In controls, a maximal IAP of 6.0 +/- 1.4 cmH(2)O (range 3-15 cmH(2)O) was registered (n = 12) at the time of the flow pressure (FP). Intravesical administration of PGE(2) or BOO did not affect the IAP at basal pressure, FP or micturition pressure. Changes in IAP due to movement or non-voiding-related straining were subtracted from IVP to generate DP and to visualize DO after BOO or intravesical PGE(2).

CONCLUSIONS

The conscious rat uses abdominal straining during voiding, and maximal IAP is recorded at the onset of urinary flow. Simultaneous registration of IAP and IVP during the micturition cycle in conscious rats is a convenient method for accurate quantification of pressures inside the bladder and for studying "true" DO without interference from movement artifacts.

The role of urodynamics in the treatment of lower urinary tract symptoms in women

PURPOSE OF REVIEW

Urodynamic investigation was developed as an extension of patient history and physical examination in order to reveal the pathology of a patient's complaints. Much progress in standardizing definitions and procedures has been made in recent years. In particular, stress urinary incontinence and overactive bladder can be differentiated with urodynamics. The developed parameters, however, cannot distinguish the various types of stress urinary incontinence. Moreover the definition and diagnosis of voiding dysfunction is not clear. Finally our understanding of bladder sensations and the impact on voiding behaviour has only started to emerge. This review is about last year's publications that focus on urodynamics and lower urinary tract symptoms in women.

RECENT FINDINGS

Defining bladder outlet obstruction is based on voiding pressure, urinary flow speed and residual urine but standardization is lacking. Urodynamics to reveal occult stress urinary incontinence in patients with pelvic organ prolapse needs standardization of the reducing manoeuvres. The quest for urodynamic tools for distinguishing intrinsic sphincter deficiency from urethral hypermobility continues. Urodynamics are still not good enough to discriminate between treatment options for stress urinary incontinence. The use of urodynamics in overactive bladder is developing and has elicited new findings. Voiding habit seems to be independent from bladder sensations. Also bladder sensations appear to be imperfectly correlated with bladder filling. Even bladder volumes do not predict entirely bladder fullness sensations.

SUMMARY

In order to use urodynamics as a proper clinical tool, defining subtypes of stress urinary incontinence and standardization of urodynamics in pelvic organ prolapse and bladder outlet obstruction in women is needed.