For the first time a surgical laser is available for soft tissue surgery which unifies all advantageous properties of existing laser principles in a single unit. RevoLix combines the cutting and ablation advantages of the well known CO2 laser – but there is no need for an articulated mirror arm. RevoLix achieves excellent hemostasis like the Nd:YAG or Diode laser – but there is no risk of deep tissue penetration. RevoLix provides excellent tissue vaporization – but unlike the KTP laser without the observed significant decrease in efficiency caused by bleaching of the target chromophore. RevoLix tissue effect is shallow like the Holmium laser – however there is no trauma produced by the laser and cutting edges are smooth and clean. In open surgery there is no splattering. RevoLix laser radiation is delivered to the surgical site through multi-use or disposable flexible fibers – ideal for endoscopic, laparoscopic and minimally invasive surgery.
- less blood loss
- quick recovery time
- out patient surgery
- less postoperative care
- short cauterization time in BPH treatment
- precise surgery
- no deep penetration
- safe operation
- excellent hemostasis
- treatment of patients under anticoagulant
- less damage to endoscopes and instruments
- reusable and disposable fibers
- color neutral safety glasses
- multi-disciplinary for minimally invasive surgery
Lasers are manufactured with a range of different wavelengths spanning from the ultraviolet to the infrared.
These different wavelengths have differing characteristics when they are applied to tissue. The chart to the right shows the absorption curve for the three chromophores at different wavelength. There are two pieces of information that can be obtained from these curves. Given the wavelength, the primary target chromophore can be determined and from that the absorption length in hemoglobin or water can be obtained. (the absorption length is the right vertical axis) The absorption length is the first indicator of the amount of thermal damage that can be created by a particular laser. (Note that the axis is logarithmic.)
How to select a suitable laser
There are four pieces of information that are critical to allow a surgeon to understand the tissue interaction of a particular laser:-
a) Wavelength of the laser energy
b) Temporal nature of the laser energy.
c) Medium that the tissue is in, i.e. water, air
d) Laser delivery system.
Selecting a laser for surgical applications is always a compromise. The surgeon would ideally prefer a device that produces clean efficient cutting with good hemostasis and no thermal damage. But, such a device does not exist. So here is the compromise, to find a balance between hemostasis on one hand while minimizing the thermal damage on the other hand.
Wavelengths Shorter than 1.2 micron (KTP, most Diode Lasers and ND:YAG)
With wavelengths shorter than 1.2 micron (KTP, most Diode lasers and Nd:YAG) there are three chromohores (but in almost all surgical procedures we can ignore melanin). The primary chromophore is hemoglobin and typically hemoglobin absorbs these wavelengths well, and has a short absorption length; however, this relies on well vascular tissue. If the tissue becomes blanched or is scar tissue the primary chromophore has been removed and now the laser energy will be absorbed by the secondary chromophore, water. The absorption length for water at these wavelengths is much longer, resulting in much more thermal damage to the tissue. While this may not be apparent from the surface, the laser energy is being absorbed over a much greater depth consequently the tissue temperature drops below the vaporization temperature (Is in Fig 2) to a point where it is just “cooking” the tissue.
Wavelengths Greater than 2.5 micron (Erbium, and carbon dioxide lasers)
At the other end of the infrared spectrum, wavelengths greater than 2.5 micron you have the erbium (2.94 micron) lasers and carbon dioxide (10.6 micron). These laser wavelengths only have one target chromophore, water, and the laser energy is very efficiently absorbed. The depth of thermal injury is short resulting in efficient vaporization of the tissue but producing poor hemostasis.
RevoLix 2 micron Thulium Wavelength
The Holmium and 2 micron CW laser have a absorption length that falls between these other two groups. The 2 micron laser was in fact specifically chosen to meet the demand for good hemostasis with acceptable thermal damage.
The development of lasers
Since lasers were first developed back in the 1960’s there has been a fixation on understanding the physics behind the laser. Then, when the laser was introduced into the medical field, this same approach was taken by the laser industry when they were marketing their laser systems. Even to this day, many laser companies still provide misleading or incomplete information when they discuss the laser technology and tissue interaction. Knowing if the laser is a YAG laser or a Diode laser doesn’t provide the necessary information to fully understand the clinical interaction. In fact, there is no such thing as a YAG laser, but still you will hear people referring to it. This is the wrong approach, because it does not give the surgeon any understanding of the laser-tissue interaction.
How Vaporization of tissue occurs
It is important to understand the thermo mechanics that take place in the tissue. The objective is to raise the temperature of the tissue to a level where it will vaporize. The volume of tissue that needs to be vaporized is defined by the diameter of the laser beam and the absorption length. To raise the temperature of this volume of tissue to a point of vaporization will take a finite amount of energy; however, this energy must be delivered to the tissue in a time frame that is quicker than it can be conducted away to the surrounding tissue. This time is known as the thermal relaxation time and is typically about a second.