Biomedical Engineering Reference
In-Depth Information
been investigated for improving the strength of cutaneous repairs [19, 97]. To
minimize the effects of collateral thermal damage dynamic cryogen cooling
was successfully employed [98]. A more recent proposal was the use of gold
nanoparticles as exogenous absorbers, which allowed for the application of
light sources undergoing minimal absorption from tissue components, thereby
minimizing the damage to surrounding tissues [99]. Previously, the ability of
laser welding to accelerate and improve the skin wound healing process was
convincingly demonstrated [100]. However, it should be emphasized that -
until now - clinical work on laser skin welding has never been reported.
15.4.6 Laser Welding in Urology
Urological surgery requires watertight closures, because of the continuous flow
of urine. As urine lacks the clotting features of blood, producing effective
closures of the urinary tract using traditional suturing techniques tends to be
technically demanding and time-consuming. Moreover, suture material itself
can induce the formation of stones. Conversely, laser welding can provide
immediate watertight, non-lithogenic anastomoses, yielding a tensile strength
that is superior to that of conventional closure techniques [5]. Laser tissue
welding has been tested on several tissues of the genitourinary tract and for
different applications, including urologic applications, which gave the best
clinical achievements.
Laser vasal anastomosis using CO
2
and noncontact Nd:YAG laser was ini-
tially investigated in several experimental studies, followed by clinical trials
with good postoperative results [101]. Afterwards, laser soldering with ICG-
doped albumin in conjunction with an 808-nm diode laser was investigated for
hypospadia repair on 138 children [18]. Results were compared with conven-
tional suturing. The study emphasized the occurrence of fewer postsurgical
complications in the laser group compared with the sutured one, and an easier
operation in the laser set-up.
15.5 Perspectives of Nanostructured Chromophores
for Laser Welding
Laser welding of biological tissues has received substantial momentum from
coupling with exogenous chromophores with enhanced absorbance in the near-
infrared, applied topically at the edges of the wounds prior to irradiation. As
mentioned earlier, suitable exogenous chromophores absorb e
ciently and se-
lectively the near-infrared light from a laser, which immediately translates
into well-localized hyperthermia and an overall decrease of the power thresh-
olds required to achieve closure of wounds. This in turn minimizes collateral
thermal damage to healthy tissues, which has ultimately backed the emer-
gence of laser-welding as a minimally invasive and convenient alternative to
traditional suturing or grafting. The ultimate exogenous chromophore should
