Pressure-flow studies before and after transurethral microwave thermotherapy of benign prostatic hyperplasia using low- and high-energy protocols.

OBJECTIVE: To compare pressure-flow results before and 3 months after transurethral microwave thermotherapy (TUMT) for benign prostatic hyperplasia (BPH), performed with lower and higher energy protocols. PATIENTS AND METHODS: Twenty-four patients were treated using a high-energy protocol performed with a heatshock strategy, i.e. a rapid increase in intraprostatic temperatures to a maximum of 55-67 degrees C. A helical antenna was used which produced maximum heating at the base of the prostate. A further 25 patients were treated using a lower energy protocol with a slow increase in intraprostatic temperatures to a maximum of 45-53 degrees C. A first-generation filament antenna was used with the maximum heat produced at the prostatic apex. All treatments were performed as single-session outpatient procedures of 60-70 min duration. RESULTS: There was a significantly greater improvement in pressure-flow variables, i.e. maximum urinary flow rate, detrusor pressure at maximum flow and minimal urethral opening pressure, in those treated with higher energy TUMT than in those receiving the lower energy protocol. The Madsen and quality-of-life scores, and maximum urinary flow rate on uroflowmetry, were also significantly better in the higher energy group. CONCLUSION: Higher energy TUMT performed using a heat-shock strategy provides a better pressure-flow outcome than lower energy thermotherapy. Compared with previously published results, the outcome after higher energy TUMT is at least similar to other treatment alternatives for BPH.

Transurethral microwave thermotherapy for benign prostatic hyperplasia--experience with the Prostcare.

Transurethral microwave thermotherapy for benign prostatic hyperplasia with the Prostcare has been used in our department since April 1992. Our research has mainly been focused on strategies for development of the apparatus, accessories, and treatment performance to find an optimal means of treatment. The development to high-power thermotherapy has demonstrated a significant improvement in symptom and quality-of-life scores, maximal flow rate, and residual and voided urinary volume after 6 months. Pressure-flow data have additionally demonstrated a significant decrease in the minimal urethral opening pressure. The improvement in outcome after high-power thermotherapy is associated with an increased short-term morbidity as compared with low-power treatment. The outcome is dependent on several factors: power and intraprostatic temperatures, treatment performance technique, configuration of heat distribution of the antennae, and the localization of maximal heat in the prostatic urethra.

Bio-acoustic signals from stenotic tube flow: state of the art and perspectives for future methodological development.

To study the degree of stenosis from the acoustic signal generated by the turbulent flow in a stenotic vessel, so-called phonoangiography was first suggested over 20 years ago. A reason for the limited use of the technique today may be that, in the early work, the theory of how to relate the spectrum of the acoustic signal to the degree of the stenosis was not clear. However, during the last decade, the theoretical basis for this and other biological tube flow applications has been clarified. Now there is also easy access to computers for frequency analysis. A further explanation for the limited diagnostic use of bio-acoustic techniques for tube flow is the strong competition from ultrasound Doppler techniques. In the future, however, applications may be expected in biological tube flow where the non-invasive, simple and inexpensive bio-acoustic techniques will have a definite role as a diagnostic method.

Estimation of elastic properties in the urethral flow controlling zone by signal analysis of urodynamic pressure/flow data.

When urethral flow is treated as a lossless flow through an elastic tube, the relationship between the detrusor pressure and the urinary flow can be related to the elasticity of the flow-controlling zone of the urethra. A recent analytical method of describing urethral elasticity is implemented on a computer. The function p(Q) = pmo + LmQm is fitted to the recorded pressure/flow data. p(Q) is the detrusor pressure, Q the flow and pmo, m and Lm parameters. The elastic properties are then obtained as p(A) = pmo + KnAn, where p(A) is the static pressure, A the cross-sectional area of the flow-controlling zone and n and Kn calculated parameters. The urodynamic methods used and the computer implementation of the analytical method are described. In obstructed and unobstructed men without neurological symptoms, the elastic properties could be estimated in 94 per cent of the micturitions. The method makes it possible to describe urethral flow properties with Griffiths' model in a standardised way and compare results obtained by different investigators. It is recommended for quantification of urethral obstruction in research and for assessment of borderline cases of obstruction in clinical practice.