Moses Capability
Lumenis Pulse 120H UM-10012510 Rev. F
Page 13
Holmium laser systems can deliver the same average power at different
settings to achieve different laser tissue effect. Changing the energy of
each pulse can be described as the “bite size” of the laser effect, whereas
the frequency as the “bite rate”. For example, setting the system at 30W
can be performed using the following sets of parameters: 1.5J at 20 Hz or
0.5J at 60 Hz.
When working with calculi, for example, these different settings may
affect the stone by breaking the stone into particles versus disintegrating
the stone into fine dust. The selection of the appropriate energy and
frequency settings is dependent on the procedure and specific target
tissue.
Each pulse is delivered at a specific time frame, leading to a rapid rise in
temperature of the target tissue. By increasing the pulse duration, the time
frame of energy delivery to the tissue changes and thereby changing the
temperature profile of the tissue. A different temperature profile may lead
to a heating rather than a vaporizing effect and is useful for example when
blood vessel coagulation is desired.
The selection of appropriate power parameters and delivery system is
dependent on the procedure and the specific patient condition. It is
recommended that you become familiar with laser characteristics and
techniques by attending courses and consulting with colleagues in order to
utilize the lasers capabilities in a safe manner.
Moses Capability
In a liquid environment when laser is emitted from the holmium fiber tip,
the water surrounding the tip heats to above the boiling temperature and a
vapor bubble is created. The vapor bubble expands from the fiber tip
towards the target tissue or stone. As only a portion of the pulse is
sufficient to create the vapor bubble, the remaining pulse energy travels
through the void contained in the bubble, and is less attenuated compared
to travel through liquid water.
When the distance between the fiber tip and the target is very small, this
phenomenon is not observed, as most of the energy reaches the target
tissue. In contact, the laser is therefore the most efficient. However, when
distance is increased, the relative energy that reaches the target is greatly
decreased, leading to reduced ablation efficiency of the laser energy. The
laser efficiency is therefore much dependent on the distance between the
fiber tip and the target. This is defined as the regular mode currently
available for all system applications.