Laser Techniques for Urinary stones

2. INTRODUCTION
Because of advances in endoscope
design and miniaturization, along
with the development of highly
effective surgical lasers,
ureteroscopy (URS) and laser
lithotripsy has become the
predominant method for urinary
stone treatment in North America
Advanced Ho:YAG technologies have
been introduced, such as the Moses
technology, a pulse modulation
mode that improves holmium laser
energy transmission through water.
The holmium:yttriumaluminum- garnet
(Ho:YAG) laser is the most widely used
laser for URS, with modern systems
providing users with a range of settings
and parameters that have numerous
effects on stone fragmentation.
The thulium fiber laser (TFL) is a new,
solid-state, diode-pumped laser
thatmay provide urologists with
increased options for stone
treatment.

3. HOLMIUM LASER
Pulse Energy (PE)
PE, measured in joules
(J), is the total optical
energy emitted from the
laser fiber tip in 1 pulse.
Frequency
Frequency, measured in
hertz (Hz), is the number of
pulses emitted from the
laser fiber per second.
Pulse Width (PW)
PW, also described as pulse
duration or length, is defined
as the duration of the single
optical pulse emitted from
the fiber tip
• The Ho:YAG laser is a solid-state, flash lamp pumped pulsed laser, and is the current standard
for lithotripsy during URS.
• Because its wavelength is 2120 nm, it is highly absorbed in water, with a low penetration
depth that limits the amount of energy reaching surrounding tissue.
• The process of ablation and fragmentation are highly dependent on the total power (Watts)
delivered to the stone, which is a product of the pulse energy (PE) and frequency.

4. Other Technical Parameters Affecting Laser Lithotripsy
The fiber tip to stone working
distance has implications on
lithotripsy efficiency because
energy from the holmium
laser is highly absorbed in
water.
Fiber Tip
Smaller core diameter fibers
are associated with more
retropulsion compared with
larger core fibers.
Fiber Size
Two other factors that affect fragmentation are the
laser fiber size, and the fiber tip to stone working distance.

5. Fragmentation and
Retrieval
To perform this technique, the laser
fiber tip should be kept at the center
of the stone, pinning it against the
urothelial wall, while firing
intermittently. This positioning allows
the stone to break into equal-sized
fragments and also decreases the risk
of damage to the urothelial wall

6. Dusting Technique
Dancing and chipping are techniques used during the
contact phase of dusting. Dancing is accomplished by
sweeping the laser fiber tip horizontally across the face
of the stone in a painting motion while firing
continuously
During this phase, stone fragments are pulverized in a
calyx with the laser activated in bursts away from the
stone, resulting in a whirlpool-like effect and stone
disintegration as the fragments come into direct contact
with the laser tip
Contact laser lithotripsy
Noncontact laser lithotripsy (Popcorn techinique)
When treating renal stones, a complete dusting technique consists of 2 phases: contact laser lithotripsy,
followed by noncontact laser lithotripsy.

7. Factors that should be considered when
performing the popcorn technique.

8. Advantages and disadvantages of dusting and retrieval techniques for ureteroscopic laser lithotripsy

9. LASER TECHNIQUES FOR PERCUTANEOUS
RENAL STONE SURGERY
Percutaneous nephrolithotomy
(PCNL) is the gold standard
treatment for stone burdens greater
than 2 cm or staghorn calculi.
The workhorse for lithotripsy during
PCNL has been the ultrasonic
and/or pneumatic device, an early
handpiece proved the utility of
combined suction with a holmium
laser fiber to permit simultaneous
lithotripsy and suction of fragments.
Laser suction devices has made the
holmium laser a viable energy
source for fragmentation during
PCNL.

10. NEW
TECHNOLOGY
• Moses technology changes how the energy is delivered to the stone, a
process called pulse modulation. The energy is delivered over 2 pulses
• The first pulse delivers part of the energy to form the vapor bubble. Once
the bubble is formed, the second pulse delivers the rest of the energy
through the already-formed vapor channel
• Moses technology can be cost-effective if the laser fiber cost can be
reduced or if the procedure time is reduced by at least 4 minutes
Moses Platform for Holmium
Laser Lithotripsy

11. EMERGING
TECHNOLOGY
• The first pulse delivers part of the energy to form the vapor bubble. Once
the bubble is formed, the second pulse delivers the rest of the energy
through the already-formed vapor channel
• Second, the energy or TFL is generated in a small fiber so it can be coupled
to laser fibers with core diameters as small as 100 mm
• Third, the range of settings available on the two laser systems are
different. TFL has pulse energies as small as 33 mJ and frequency as high
as 2000 Hz, compared with the holmium laser in which 200 mJ is the
lowest PE and 80 Hz is the highest currently achievable frequency
Thulium Fiber Laser (TFL)

12. Comparison of The Moses Effect and
The Moses Technology for HO:Yag Laser

13. Summary
Laser techniques during endoscopic stone surgery can result
in fragments that are small enough for retrieval or small
enough for spontaneous passage
High PE is used for active retrieval, whereas low PE is used
for dusting technique. LP mode results in less stone
retropulsion and fiber tip degradation.
The popcorn technique is used to pulverize stones into fine
fragments and is an important endgame strategy for dusting.
The Moses technology for the holmium laser is a pulse
modulation method that delivers energy over 2 pulses in
order to reduce retropulsion and increase fragmentation.
The TFL is an emerging laser technology, and future research
will help clinicians understand how to incorporate these
technologies and techniques with the aim of improving
patient outcomes.

14. Thank you