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Current
Medical Scene
vol.17 No.2 April - June, 2002
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Benign
prostatic hyperplasia (BPH) is the most common benign neoplasm
(non cancerous enlargement of the prostate gland) in men.
It has a high prevalence rate that increases with age. Severe
obstructive BPH can lead to urinary retention, infections,
hematuria and renal failure.
It is important to tailor treatment based on the individual
patient. For mild to moderate symptoms, medical therapy is
a valid option. For severe symptoms, surgery is the most effective
treatment. However, it is also the most invasive and carries
the highest risks for significant complications, including
impotence and incontinence. The most common surgery procedure
is to 'core out' the prostate gland, an operation that is
known as trans- urethral resection of the prostate (TURP).
Another operation that is performed with a cystoscope is the
trans-urethral incision of the prostate (TUIP). In this, a
cut is made in the bladder neck or along the length of the
prostate to relieve the pressure on the urethra.
These conventional techniques are associated with post-operative
bleeding, morbidity, hospital stay and high costs. Patients
requiring prostate surgery now have the option of the more
modern laser prostatectomy, which was approved by FDA in March
1996.
RECENT ADVANCES IN LASER PROSTATECTOMY
Various surgical lasers have been used for prostatectomy to
coagulate and/or vaporise the tissue. There are five main
variations of laser prostatectomy, four of which use the neodymium:Yttrium-aluminum-garnet
(Nd: YAG) laser. The most recent method uses Holmium YAG laser.
Nd:YAG Laser
The laser most commonly used to treat the prostate has been
the neodymium:yttrium aluminium garnet (Nd:YAG) laser, which
generates 1064 nm light. It employs side-firing laser fibres
and Nd: YAG lasers to vaporise obstructing prostate tissue.
The fibre is passed through the urethra into the prostate
using a cystoscope. The urologist aims the laser beam at the
tissue and delivers several short bursts of laser energy (30
to 60 seconds each). The prostate tissue heats up rapidly
as it absorbs the laser energy. This thermal effect results
in destruction of the prostate tissue in two ways. First,
the surface of the prostate vaporises causing immediate loss
of tissue. Then the deeper tissue is destroyed by coagulation
necrosis, which results in delayed sloughing of tissue over
six to eight weeks. The procedure is done under a general
or regional (spinal) anaesthetic and may take 30 to 60 minutes.
The patient stays in the hospital for 24 to 48 hours. However,
the catheter is left in for three to seven days, depending
on the size of the prostate.
There are four laser techniques that use Nd:YAG laser:
1. Transurethral ultrasound-guided prostatectomy (TULIP).
2. Visually guided laser ablation of the prostate (VLAP).
3. Contact laser ablation of the prostate (CLAP).
4. Interstitial laser coagulation of the prostate (ILCP).
Coagulation is the main mechanism of action for TULIP and
VLAP. CLAP and ILCP induce immediate vaporisation of surface
tissue.
Holmium: YAG laser
The Holmium:YAG (Ho:YAG) laser is perhaps the most versatile
surgical laser available for laser prostatectomy. The unique
ability of the Ho:YAG to vaporise, ablate and coagulate soft
tissues has made it the laser of choice for laser surgeons
worldwide. It combines the qualities of the carbon dioxide
and neodymium:YAG lasers providing both tissue cutting and
coagulation in a single device. The Holmium: YAG laser is
a solid-state, pulsed laser that emits light at 2140 nm. The
Ho:YAG wavelength is strongly absorbed by water. In tissue
the absorption length is relatively short (0.4 mm). The zone
of coagulation necrosis is limited to 3 to 4 mm which is sufficient
for adequate hemostasis in the prostate. The peak power achieved
per pulse is in the kilowatt range which results in intense
tissue vaporisation and a precise and efficient cutting ability
in prostatic tissue. Recently, holmium:YAG lasers of up to
80 watts average power have been introduced. These can be
used in an aqueous environment.
RISKS AND BENEFITS OF LASER PROSTATECTOMY
Post-operative catheter times are generally longer following
laser prostatectomy. There is a delay in the ultimate outcome
and the irritative symptoms last longer post operatively.
However, Holmium: YAG laser overcomes these limitations. With
this laser, there is no risk of bleeding (no blood transfusions),
or, hospitalisation is for a very short period (normally just
one night), there is no need of bladder irrigation after the
procedure, patient can return to active life within two or
three days, and the risk of impotence or incontinence is minimised.
CURRENT STATUS AND FUTURE PROSPECTS
In India, this technique is available in Mumbai, Pune and
Delhi. Holmium laser prostatectomy is undergoing rapid evolution.
With improvements in laser technology and instrumentation,
we could see a new standard of treatment emerge in next few
years. Holmium laser enucleation of the prostate (HoLEP) is
the immediate future of holmium prostatectomy. This involves
using the laser fibre like a transurethral 'index finger'
in that the fibre sweeps the entire adenoma, intact, off the
surgical capsule using a retrograde approach similar to open
prostatectomy. This can be used in prostates of all sizes
but is considerably faster to perform in many of the larger
glands than TURP. Combined use of laser and mechanical techniques
may allow safe and rapid treatment of prostates of virtually
any size with minimal postoperative morbidity.
CONCLUSION
Laser therapy of BPH is an established, durable, effective,
and safe technique. It offers an exciting new alternative
with potential advantages over conventional methods. It is
a less invasive alternative to transurethral resection of
prostate. All methods of laser prostatectomy improve flow
rates and symptoms, minimise blood loss and fluid absorption,
and decrease hospital stay, impotence rates and bladder neck
contractures.
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