Benedikt Kranzbühler, Oliver Gross, Christian Fankhauser, Lukas Hefermehl, Cédric Poyet, Remo Largo, Michael Müntener, Hans-Helge Seifert, Matthias Zimmermann, Tullio Sulser, Alexander Müller, Thomas Hermanns
Introduction and objectives: Greenlight laser vaporization (LV) of the prostate is characterized by simultaneous
vaporization and coagulation of prostatic tissue resulting in tissue ablation together with excellent hemostasis during the
procedure. It has been reported that bipolar plasma vaporization (BPV) of the prostate might be an alternative for LV. So
far, it has not been shown that BPV is as effective as LV in terms of tissue ablation or hemostasis. We performed
transrectal three-dimensional ultrasound investigations to compare the efficiency of tissue ablation between LV and
BPV.
Methods: Between 11.2009 and 5.2011, 50 patients underwent pure BPV in our institution. These patients were matched
with regard to the pre-operative prostate volume to 50 LV patients from our existing 3D-volumetry-database. Transrectal
3D ultrasound and planimetric volumetry of the prostate were performed pre-operatively, after catheter removal, 6 weeks
and 6 months.
Results: Median pre-operative prostate volume was not significantly different between the two groups (45.3ml vs.
45.4ml; p=1.0). After catheter removal, median absolute volume reduction (BPV 12.4ml, LV 6.55ml) as well as relative
volume reduction (27.8% vs. 16.4%) were significantly higher in the BPV group (p<0.001). After six weeks (42.9% vs.
33.3%) and six months (47.2% vs. 39.7%), relative volume reduction remained significantly higher in the BPV group
(p<0.001). Absolute volume reduction was non-significantly higher in the BPV group after six weeks (18.4ml, 13.8ml;
p=0.051) and six months (20.8ml, 18ml; p=0.3). Clinical outcome parameters improved significantly in both groups
without relevant differences between the groups.
Conclusions: Both vaporization techniques result in efficient tissue ablation with initial prostatic swelling. BPV seems
to be superior due to a higher relative volume reduction. This difference had no clinical impact after a follow-up of 6M.
Oliver Gross, Tullio Sulser, Lukas J. Hefermehl, Daniel D. Strebel, Remo Largo, Ashkan Mortezavi, Cédric Poyet, Daniel Eberli, Matthias Zimmermann, Alexander Müller, Maurice S. Michel, Michael Müntener, Hans-Helge Seifert, Thomas Hermanns
Introduction and objectives: It is unknown if tissue ablation following 120W lithium triborate (LBO) laser
vaporization (LV) of the prostate is comparable to that following transurethral resection of the prostate (TURP).
Therefore, transrectal 3D-ultrasound volumetry of the prostate was performed to compare the efficiency of tissue
ablation between LBO-LV and TURP.
Methods: Between 03/2008 and 03/2010 110 patients underwent routine LBO-LV (n=61) or TURP (n=49). Transrectal
3D-ultrasound with planimetric volumetry of the prostate was performed pre-operatively, after catheter removal, 6 weeks
and 6 months.
Results: Median prostate volume was 52.5ml in the LV group and 46.9ml in the TURP group. After catheter removal,
median absolute volume reduction (LV: 7.05ml, TURP: 15.8ml) and relative volume reduction (15.9% vs. 34.2%) were
significantly lower in the LV group (p<0.001). After 6 weeks/ 6 months, the relative volume reduction but not the
absolute remained significantly lower in the LV group.
Conclusions: LBO-LV is an efficient procedure evidenced by an absolute tissue ablation not significantly different to
that after TURP. However, TURP seems to be superior due to a higher relative tissue ablation. The differences in tissue
ablation had no impact on the early clinical outcome. Delayed volume reduction indicates that prostatic swelling occurs
early after LV and then decreases subsequently.
It has recently been shown that laser fibre deterioration leads to a significant decrease of power output during 80 W
potassium titanyl phosphate (KTP) laser vaporisation (LV) of the prostate. This decrease results in inefficient
vaporisation especially towards the end of the procedure. For the new 120 W lithium-triborate (LBO) High Performance
System (HPS) laser not only higher power but also changes in beam characteristics and improved fibre quality have
been advertised. However, high laser power has been identified as a risk factor for laser fibre degradation. Between July
and September 2008 25 laser fibres were investigated during routine 120 W LBO-LV in 20 consecutive patients. Laser
beam power was measured at baseline and after the application of every 25 kJ during the LV procedure. Postoperatively,
the surgeon subjectively rated the performance of the respective fibre on a scale from 1 to 4 (1 indicating perfect and 4
insufficient performance). Additionally, microscopic examination of the fibre tip was performed. Median energy applied
was 212 kJ. Changes of power output were similar for all fibres. Typically, a steep decrease of power output within the
first 50 kJ was followed by a continuous mild decrease until the end of the procedure. After the application of 50 kJ the
median power output was 63% (58-73% interquartile range) of the baseline value. The median power output at the end
of the 275 kJ-lifespan of the fibres was 42% (40-47%). The median surgeons' rating of the overall performance of the
laser fibres was 2 and the median estimated final decrease of power output 60%. Some degree of degradation at the
emission window was microscopically detectable in all cases after the procedure. However, even after the application of
275 kJ, these structural changes were only moderate. Minor degradation of the laser fibre was associated with a
significant decrease of power output during 120 W LBO-LV. However, following an early, steep decrease, power output
remained relatively constant on a medium level for the rest of the fibre's lifespan. The subjective rating by the surgeons
is in accordance with these findings. Improved properties of the LBO laser and enhanced fibre quality resulted in an
only moderate decrease of power output which allowed for a consistently effective performance.
Photoselective vaporization of the Prostate (PVP) using the 80W-Greenlight-PV(R) Laser System (Laserscope(R), San
Jose, USA) has been established as a treatment option for patients suffering from obstructive symptoms caused by
benign prostatic hyperplasia. However, longer operation time compared to standard trans-urethral resection of the
prostate (TURP) and the high costs of the laser fibers are specific problems of this technique. In addition, many
clinicians performing PVP complain about a reduced effectiveness of vaporization during treatment. Therefore,
power measurement was performed during PVP using the 80W-Greenlight-PV(R) Laser System. Power output was
measured at the beginning and also regularly throughout the operation. A total of 40 fibers were investigated in 35
patients. Damage to the tip of the fibers was regularly visible and increased as more energy was supplied.
Additionally, in 90% of all fibers a decrease of power output was detectable during the operation. This became
pronounced after the application of 200kJ, resulting in an end of lifespan (i.e. 275kJ) median power output of only
20% of the starting value. Corresponding to the clinical observations the impressive damage to the emission
window was associated with a substantial decrease of power output during PVP. These observations might explain
the impaired vaporization during PVP and a longer operation time compared to conventional TURP. Hence,
improvements in the quality of the laser fibers are necessary to advance the efficiency of this promising technology.
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