A technique for measurement of related values of pressure and cross-sectional area in the male urethra

Urethral pressure reflectometry, a novel technique for simultaneous recording of pressure and cross-sectional area in the prostatic urethra: testing in men without bothersome lower urinary tract symptoms

OBJECTIVE

Urethral pressure reflectometry (UPR) was introduced in 2005, for simultaneous measurement of pressure and cross-sectional area in the female urethra. It has shown to be more reproducible than conventional pressure measurement. Recently, it has been tested in the anal canal and the prostatic urethra. The primary aim of this study was to describe UPR in men without bothersome lower urinary tract symptoms.

MATERIAL AND METHODS

The study investigated 18 men, median age 59 (range 50-77) with UPR and pressure-flow analyses (PQ), the International Prostate Symptom Score and the Danish version of Prostate Symptom Score, flow rate, residual urine measurements, transrectal ultrasound, urethral pressure profilometry and visual analogue scale (Discomfort). UPR parameters measured were opening and closing pressure, opening and closing elastance and hysteresis, from the bladder neck to the sphincter region.

RESULTS

All UPR parameters increased significantly from the bladder neck to the sphincter region, except for the opening pressure between the prostate and the sphincter region. Seven men were obstructed according to PQ, but with no significant differences in any other standard urodynamic parameters. The hysteresis in the sphincter region was significantly lower in the obstructed group (p = 0.005). Discomfort was significantly lower with PQ compared to UPR (p = 0.04). Nine men had slight bleeding from the urethra during measurement with UPR.

CONCLUSIONS

The increase in all parameters from the bladder neck to the sphincter region is consistent with previous studies measuring the same parameters. The hysteresis may explain why seven men were obstructed according to PQ.

Urethral pressure reflectometry; a novel technique for simultaneous recording of pressure and cross-sectional area: a study of feasibility in the prostatic urethra

What's known on the subject? and What does the study add? In the 1980s and 1990s, a method for direct measurement of pressure and cross-sectional area in women and men was developed. It was successful in terms of obtaining meaningful results in several studies. But the technique, which was based on the field gradient principle, was never implemented in the clinical setting because of technical limitations. In 2005, urethral pressure reflectometry was introduced as a new technique in female urodynamics. The technique has been shown to be more reproducible than conventional urethral pressure profilometry, when measuring incontinence in women. In 2010 it was also introduced as a new measuring technique in the anal canal. This study, adds a new and interesting technique to the field of male urodynamics. For the first time, sound waves have been used to measure pressure and cross-sectional area simultaneously, directly in the prostatic urethra. The results from this first trial with urethral pressure reflectometry are promising, in terms of obtaining meaningful physiological parameters. Our hope is that, future trials will help us to be able to identify specific areas of obstruction or rigidity in the prostatic urethra, making treatment more direct and side effects from surgery less severe. However, further studies are needed to evaluate the technique with regards to clinical usefulness in men with benign prostatic obstruction.

OBJECTIVE

Urethral Pressure Reflectometry (UPR) was introduced in 2005, and it has since been used in the female urethra for simultaneous measurement of pressure (P) and cross-sectional area (CA). It has shown to be more reproducible than conventional pressure measurement and reintroduced direct measurement of pressure and elastance in the urethra as important parameters when assessing incontinent women. To test the feasibility of UPR in the prostatic urethra.

PATIENTS AND METHODS

We tested the technique in ten male patients, median age 73 and range 51-91. Measurements were performed in the supine position, with less than 50 ml of urine in the bladder. The UPR valuables measured were opening and closing pressure, opening and closing elastance and hysteresis.

RESULTS

The PVC tube was easy to insert to the same degree as a normal KAD. Opening pressure and opening elastance were measured on all patients. The sphincter area was easily identified during measurements. UPR provides results compatible with previous techniques. A standardized method for measurements was developed.

CONCLUSION

UPR has been shown feasible in the prostatic urethra. Further studies on healthy volunteers and patients with lower urinary tract symptoms and benign prostatic obstruction (BPO) are needed, to determine if UPR has a future role in urodynamic diagnostics of male patients with BPO.

Distensibility of the mouse rectum: application of impedance planimetry for studying age-related changes

Rectal distensibility is an important parameter for investigation of anorectal function. The aim of the present paper was to study pressure-cross-sectional area (CSA) relations and distensibility of the rectum in mice aged 15-78 weeks using impedance planimetry. A four-electrode probe system located inside a balloon was designed to determine pressure-CSA relations in the mouse rectum. CSA was estimated from measurements of the electrical impedance of saline inside a balloon. The method was validated in studies in vitro showing high accuracy and good reproducibility. The method was applied in measurements of inter- and intra-individual variation and age-related variation of rectal pressure-CSA relations and distensibility. Repeated distension every third day in a cohort of 10 mice did not change the CSA during a 4-week period and there was no long-term effect of repeated measurements. There was an age-related increase in rectal CSA in the distended state until the mice were 26 weeks of age (P = 0.004). The unloaded size of the rectum did not change with age. The distensibility of the rectum did not vary significantly with age, though there was a tendency to a higher distensibility during growth followed by decline with age (P = 0.08). In conclusion, this study presents a simple, minimally invasive in vivo model for repeated evaluation of rectal distensibility in mice. The mouse model will provide a tool for analysing relative changes in rectal biomechanical properties in different future disease models.