Discussion
Saline irrigation has been paramount for CRS treatment, with its role
recently being
considered as a vehicle to deliver anti-inflammatory drugs into the
sinus. The sinus ostium is not the sole targeted area for medical
exposure, but the distribution of the drug to the sinus mucosa is also
key to restoring the disease. Thus, the modification of the delivery
system has been developed with a much greater focus on the distribution
method of the drug into the sinus cavity. There has been a growing
amount of robust evidence on the administration of corticosteroids via
nasal irrigation with respect to technically distributing medication
into the sinus and clinically improving symptoms; however, most studies
to date have been conducted on post-surgical sinus
status.(2-5) Therefore, corticosteroid nasal irrigation as an
initial treatment before the sinus surgery has not been adopted as a
general practice. Clinically, Jiramongkolchai P. et
al.(15) recently conducted a randomized controlled trial that
showed the comparable efficacy of corticosteroid irrigation and spray in
CRSsNP patients who have not undergone sinus surgery regarding the
improvement of SNOT-22 scores. In addition, Tait et
al.(16) carried out another randomized controlled trial to
investigate the efficacy of large-volume, low-pressure corticosteroid
irrigation compared with a placebo in CRS patients, of which 70% of
patients in the study never had any sinus surgery. The authors reported
that the mean change of SNOT-22 scores from baseline was greater for the
treatment group in the subgroup of patients who had no prior sinus
surgery; however, the results were not significantly different.
Regarding the technical concept, some publications investigated the
extent of sinus
distribution among the delivery system in the unoperated
sinus.(9-11, 17) However, most studies have been done on the
cadavers, and in healthy subjects, which might not sufficiently
represent the actual physiology of diseased sinuses and the natural
mechanisms of oropharyngeal functions during sinus irrigation. Moreover,
the role of the mucociliary function that might impact the sinus
penetration of the solution was one of the biases from previous
studies. Wormald PJ. et al.(10) reported the restriction of
radioactivity via nuclear medicine imaging in unopened sinus cavities on
healthy control subjects. Most radioactivity appeared in the maxillary
sinuses from nasal douching, while there no radioactivity was detected
in any sinus cavity from the spray and nebulizer techniques. Harvey RJ.
et al.(9) conducted a study on cadavers and reported a
significant limitation of contrast distribution in unoperated sinuses,
particularly in sphenoid and frontal sinuses, regardless of the delivery
technique. Another study conducted in the pathological sinuses by
Grobler A. et al.(17) found that both unoperated sinuses and
sinuses with a small sinus ostium even after sinus surgery had
unreliable penetration. However, the results of this study were not
compared with the other delivery methods. The following research by
Snidvongs K. et al.(11) utilized a comparative study between
nasal irrigation and nasal spray. Nevertheless, they used low-volume
nasal irrigation and found neither the nasal irrigation nor the nasal
spray could enhance sinus penetration in the unopened sinus.
The present study’s advantage was the fact that it was designed to
dynamically evaluate
the potential sinus distribution of different delivery methods in actual
pathological sinuses. In addition, the alternative intervention that was
intended to be investigated has been proven as a gold standard in terms
of high-volume irrigation to deliver drugs into the opened sinus
cavity.(6) This study confirmed
that
the overall sinus distribution of nasal irrigation had significantly
more superiority than the nasal spray with the conclusive effect size.
In addition, the effect of nasal irrigation could create a greater sinus
distribution in each anatomical site. However, consistent with previous
studies, the maxillary and anterior ethmoid sinuses were the most
significantly affected areas.(9,10) The OMU was the area that
could reach the solution regardless of the delivery method. The rest of
the sinuses, particularly the frontal and sphenoid sinuses, had the
least significant solution distribution from both techniques. These
limitations were explained by their anatomical locations, which sit at
the most posterior and superior parts of the paranasal sinus system.
Also, the bony septation and the sinus pathology under the unoperated
sinus were critical barriers blocking the flow pathway. In the subgroup
analysis, the difference in sinus distribution between the two methods
was significantly greater, and remarkable in the moderate to severe
sinus diseases, in which nasal irrigation had a better result. In the
CRSwNP patients, nasal irrigation, regardless, provided significantly
greater overall sinus distribution than nasal spray but had less
significant effect than the CRSsNP subgroup.
Theoretically, saline irrigation has mechanisms as removing crust and
mucous, reducing
antigen load, enhancing ciliary beat, and response for a vehicle to
deliver the drugs into the sinus. This intervention brings the advantage
of opportunely providing anti-inflammatory medications into the sinus
using a one-step approach, resulting in more satisfactory compliance of
the patients. Furthermore, sufficient therapy duration might help
relieve inflammation at the OMU, maxillary and ethmoid sinuses,
ultimately promoting the distribution of the drug into the most
challenging parts, i.e., the frontal and sphenoid sinuses. Fortunately,
as per the updated evidence, the adverse events of corticosteroid
irrigation showed no serious effects, even in long-term
use.(18-20)
The limitation of this study was that sinus penetration of a solution
can be influenced by
multiple factors, not only the delivery technique, and such factors,
i.e., the head position and the surgical status of the sinus cavity,
were beyond the context of this study. In addition, finding of this
study could not represent the symptomatic outcomes in clinical
applications and could not entirely be used as a substitute for the
standard therapy. Therefore, using corticosteroid irrigation as the
initial treatment for CRS in selected phenotypes, i.e., moderate to high
severity sinus diseases on CT scan or CRSsNP, might potentially benefit
clinical outcomes. Further study on specific phenotypes or even
endotypes might increase the extension of clinical application.