Ho:YAG Fibers: One 'Size' Does Not Fit All September 19 2016
Today I was asked a question by a prospective customer that I wish to share with the marketplace at large; that marketplace being laser surgical intervention for kidney and gall bladder stones by endoscopy.
Q – I have then an additional question, why do you make 2 SMA version adapted to different brand of laser box. When I look at most of urology company offers, they mentioned that their fibers are compatible with SMA connector but indistinguishably if there are specific for Dornier/AMS or Quanta/Lumenis. What is the difference between the referenced fibers (LT/TG): power limitation?
A - The short answer is that other’s fibers necessarily compromise performance for simplicity of design: one model can’t possibly work optimally for such different laser focal conditions and wavelengths. This is why Boston’s AccuMax* and Flexiva* exist (kudos, Boston Scientific). In general, single source (brick/head) lasers produce better beam quality and therefore smaller focal spots, but this is just not the case for medical grade holmium lasers.
There are three different laser rod chemistries that are all called “holmium”, with different wavelengths and different benefits and faults: maximum energy density (goes to minimum rod diameter and length), thermal lensing (blooming under heat), efficiency, etc. There are single head lasers, dual head lasers, tri-head lasers and quad-head lasers and different methods are used to combine the output of multiple heads. Some lasers are pumped with flashlamps and some use diode pumping. Even the SMA ports are slightly different, e.g. one manufacturer only uses ports measuring from the bore nominal to the bore minimum so + tolerance SMAs will not fit.
Dornier, New Star and StoneLight lasers use a similar laser brick design, with the same rod chemistry and similar wavelength and are all single brick lasers, but the focal spots for these lasers are larger than that produced by Lumenis multi-brick lasers. Lumenis also uses a different rod chemistry for a wavelength that is some 60 nm longer than the others. Quanta's laser is a single brick but it produces an output that is very similar to Lumenis’ four brick lasers due a different power ramping strategy. Trimedyne uses two bricks combined in a very different manner than Lumenis to produce an output similar to Dornier is focal spot size and wavelength.
I have only a little experience with Chinese holmium lasers, but the word on the street is that higher power Chinese lasers (multiple bricks) can produce fairly large focal spots that are 'impossible' to couple to small core fibers safely. (We do not believe in impossibility at InnovaQuartz, and we've made small fibers for large focal spot lasers in the past, e.g. true 200 micrometer core fibers for DEKA Smart 2100 with a 0.5 mm spot, before bloom.)
My old SureFlex 200 (LLF200TG), when I made them pre-2007, was >85% efficient on all SMA lasers except the DEKA, but it was never >93% on any of them. Other ‘one fiber fits all’ designs usually work best on Lumenis, at <90%, and I am not aware of any that are as good as the old SureFlex 200 on a Dornier or New Star/AMS laser.
When you look at all of the differences it is possible to group certain laser models into similar design groups, but it is impossible to make a fiber that works well on them all. Chinese lasers have SMA ports, too, but nobody makes a 200 μm or 273 μm fiber that works on them (yet). Iranian lasers have SMA ports but they can’t get our fibers so they have no small core, flexible fibers, either. Convergent has a modified SMA port and we’ve chosen not to make fibers that fit their lasers, so far (that may change). Trimedyne uses a proprietary laser port but we DO make fibers to fit those lasers (and our LLF200TG-Ts work better than their 273s – and they don’t make a true 200).
If you do not mind blowing scopes, lenses and blast shields, a single design may be right for you. But if you don’t like dealing with angry surgeons, exasperated nurses and reports to regulatory officials, perhaps you’d prefer more refined designs like our ProFlex LLF.
I hope that answers your questions. If not, I do have a long answer but it will have to wait until we have mutual confidentiality between us.
* AccuMax and Flexiva are trademarks of Boston Scientific. Smart 2100 is a trademark of DEKA m.e.l.a. SureFlex is a trademark of AMS. ProFlex is an InnovaQuartz trademark. Copyright 2016 IQllc.