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THE EFFECTIVENESS OF PHOTODYNAMIC THERAPY IN THE
SURGERY OF RECURRENT LARYNGEAL AND TRACHEAL
PAPILLOMATOSIS
Sadykov R.A.
Hayaliev R.Ya.
Azadov B.R.
RSSPMCS named after Academician V.Vakhidov,
RSPCSM, Urgench branch of TMA, Uzbekistan
https://doi.org/10.5281/zenodo.14162757
Relevance.
Recurrent respiratory papillomatosis (RRP) is the most
common, as well as the most expensive benign neoplasm of the respiratory tract
in the United States. There are reports of the clinical benefits of therapeutic
vaccines for patients with RRP. But none of the reports have definitively
demonstrated the induction of HPV-specific T cell responses, suggesting that
some or all of the clinical benefit caused by this treatment was due to local, non-
specific antiviral inflammatory reactions involving type I interferon. To date, at
least 50 different treatment methods are known, none of which guarantees a
lasting cure. The problem of radical treatment of respiratory papillomatosis still
remains unresolved. The use of lasers in papillomatosis surgery is a generally
recognized preferred method due to their undoubted advantages over cold
instruments. There are not many reports in the literature on the use of laser and
photodynamic therapy (PDT) for respiratory papillomatosis, especially in recent
years. The use of PDT reduces the aggressiveness of the course of respiratory
papillomatosis, in particular papillomatous lesions of the larynx. An analysis of
the literature data indicates that the results of surgical treatment of patients
with laryngeal and tracheal papillomas cannot be considered satisfactory, there
is a need for repeated therapeutic measures, an integral part of which is
considered to be high-precision and minimally invasive endoscopic and laser
surgery. The aim of our experimental study was to evaluate the effect of
semiconductor IR laser radiation followed by PDT on the mucous membrane of
the larynx and trachea.
Materials and methods:
The advantage of an IR diode laser is the ability to
generate radiation in the near-infrared spectrum of 1.36 microns, which
penetrates deep enough into biological tissues and can be delivered to the
affected area through flexible monofilament optical fibers of arbitrary diameter.
We used a Giga laser for research with a maximum power of 15W, light guides
with a diameter of 400 mm. The frequency of radiation, as well as the power, can
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be varied. For experiments on rabbits, a radiation power of 3W, an effect on an
area with a diameter of 3mm, and a pulse duration of 20 milliseconds were used.
At the same time, the energy of the laser exposure was 20-30 J. The research was
performed in the Laboratory of Experimental Surgery of the State Institution
"RSSPMCS named after Acad. V.Vakhidov". Mongrel rabbits and mini pigs were
used as experimental animals. 5-aminolevulinic acid was used as a
photosensitizer. Light-optical micrographs were obtained using a “DN-300M”
microscope coupled with a digital camera and a computer. All micrographs were
processed and stored on a computer using Microsoft's Windows 10 pro
application programs. The method of exposure consisted in conducting a
catheter into the lumen of the trachea according to the method described above.
Then the catheter was removed and the trachea, vocal cords and larynx were
irradiated with a laser at the specified dosage with a frequency of 1-2 Hz. Laser
treatment of the trachea and larynx required 10-15 laser flashes (200-350 joules
of radiation).
Results:
The conducted studies have allowed a deeper understanding of the
mechanisms of the effect of a diode laser in combination with photodynamic
therapy (PDT) on the tissues of the larynx and trachea. During the experiments,
it was found that the radiation of a diode laser has a significant effect on the
deeper layers of the laryngeal and tracheal walls, including cartilage tissue. This
effect leads to the development of an inflammatory process, which can further
contribute to the excessive growth of connective scar tissue, which is especially
important in the context of the prevention of cicatricial strictures of the
respiratory tract. In the early stages after laser exposure (in the first 2-3 days), a
pronounced inflammatory reaction is observed, which is confirmed by
morphological data. In the tissue of the larynx and trachea, neutrophil
infiltration, swelling of the submucosal layer, as well as necrotic changes in the
epithelium are noted. These morphological changes indicate that laser radiation
causes significant cell damage, which leads to activation of the local
inflammatory response. It is important to note that at this stage regenerative
processes are just beginning to manifest themselves and are characterized by
the initial stage of epithelialization, which remains poorly expressed. The use of
photodynamic therapy using a photosensitizer (FS) of 5-aminolevulinic acid (5-
ALA) and subsequent laser irradiation in the range of 630 nm led to significant
changes in the dynamics of the inflammatory process and tissue regeneration. It
was found that PDT has a modulating effect on the inflammatory process,
delaying the proliferative phase of inflammation. This is manifested in a
CURRENT APPROACHES AND NEW RESEARCH IN
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decrease in the intensity of granulation tissue growth and a decrease in the
degree of scarring. Morphologically, this is expressed in a decrease in the
number of inflammatory cells and an acceleration of the epithelialization
process, which becomes more active on 5-7 days after exposure. On the 14th
day, the tissue regeneration process is almost complete. The epithelial cover is
completely restored, and the submucosal layer shows signs of maturation of
fibrous tissue, which is a characteristic sign of the completion of reparative
processes. Studies have shown that the use of PDT in combination with laser
irradiation contributes not only to accelerating tissue healing, but also to
reducing the risk of pathological scarring, which is extremely important for
maintaining normal respiratory tract function.
Conclusions:
In the performed studies, it was found that the use of a diode laser
in combination with photodynamic therapy (PDT) has a significant effect on the
deep structures of the laryngeal and tracheal walls, including cartilage tissue.
Laser radiation causes a pronounced inflammatory reaction in the first 2-3 days
after exposure, which is accompanied by neutrophil infiltration, swelling of the
submucosal layer and necrotic changes in the epithelium. These processes
create conditions for the development of excessive growth of connective scar
tissue. The use of PDT using a 5-ALA photosensitizer and laser irradiation in the
630 nm range demonstrated the ability to modulate the inflammatory response,
delaying the proliferative phase of inflammation and reducing the intensity of
scarring. The combination of a diode laser and PDT with FS 5-ALA is a promising
method for the prevention of scarring of laryngeal and tracheal tissues, which
can significantly improve clinical outcomes and maintain normal respiratory
tract function in patients
