DISCUSSION
The present study expands the perspectives in the therapeutic follow-up
of children with asthma, mainly in reference centers. Few studies have
been published on the subject in in children in this age group.
. The sample size was adequate and the success rate was 58%, comparable
to that of similar studies, since it is a specific population,
reflecting a good applicability of the method to the pediatric
population12. In addition, the method proved to be
safe. No patient had adverse events or had to interrupt the procedure.
Bronchospasm was not observed during the procedure, even in the case of
an asthmatic population. Proven safety of the procedure and the
incorporation into the routine of the investigation of children with
asthma in our center, there was an increase in the number of viable
samples, when compared to the beginning of the study execution.
There was a predominance of children with severe asthma in the study
population. Justified by the fact that the study was conducted in a
tertiary hospital that serves patients of greater complexity and is a
reference for primary health care services in the region.
The predominance of the eosinophilic pattern in the sputum pattern
(54%) was expected and has already been described in other studies,
mainly in children, who frequently present the allergic phenotype.
Eosinophils are the main inflammatory cells in the pathogenesis of
asthma, especially in atopic patients, who generally have a profile of
Th2 cytokines, represented by IL-4, IL-5 and IL-13, blood eosinophilia
and increased total IgE 13,14.
Another important finding in this study was the positive correlation
between sputum and blood eosinophil counts. Although some studies do not
show this correlation, this correspondence is interesting since the
collection of peripheral blood is easier and more accessible when
compared to sputum induction and could be used to guide and monitor the
treatment of childhood asthma. Further studies are needed to clarify
this association15,16,17.
The considerable frequency of non-eosinophilic phenotypes (neutrophilic
and pauci-granulocytic) is noteworthy in these asthmatic patients
(43.5% of the sample).
Sputum neutrophilia is related to severe asthma in adults, resistant to
treatment with inhaled corticosteroids and less related to
atopy4. In pediatrics, several hypotheses about the
presence of neutrophils in sputum have been formulated, including the
greater occurrence of viral infections, which are known to generate
neutrophilic inflammation. Sputum is not routinely analyzed in children
with acute respiratory symptoms, which could elucidate the finding and
to avoid bias. Another hypothesis suggested would be that there would be
an increase in neutrophils in the bronchial mucosa in response to
treatment with corticosteroids inhaled by chemotaxis and inhibition of
apoptosis of these cells in sputum 18,19. In view of
this, an initial eosinophilic pattern could hypothetically become mixed
with treatment with inhaled corticosteroids. In this study, there was no
significant difference between sputum cytological profiles and
children’s inhalation treatment, but the cross-sectional character of
the study is a limitation. In a longitudinal study evaluating
treatment-resistant pediatric patients with severe asthma, Eller et al.
reported a greater number of eosinophils in the initial induced sputum
of patients who obtained better control of asthma, with a tendency to
become pauci-granulocytic in the final sample20. The
authors showed that the presence of neutrophils was higher in the sputum
of children with uncontrolled asthma20. In this study
group there was a predominance of the eosinophilic pattern even in
children using inhaled corticosteroids as well as children with
non-eosinophilic sputum pattern were not all in the uncontrolled asthma
group. The follow-up, with serial sputum evaluations of the same
patient, may clarify this question.
Allergic comorbidities were prevalent in the studied group, with
percentages of rhinitis and atopic dermatitis similar to those of two
other studies developed in Brazil21,22,23. Almost all
asthmatics evaluated had allergic rhinitis, drawing attention to this
frequent association23. This atopic profile was
confirmed by a high frequency of total IgE above normal and peripheral
eosinophilia in the study population.
Most patients (85%) were sensitized, especially to household dust
mites, again confirming the atopic profile of the population and
according to data published from other Brazilian cities24,25,26. In the case of children with moderate to
severe illness, recommendations to avoid exposure to these allergens
should be emphasized at each visit.
Lung function was normal in most patients, despite having clinically
moderate or severe asthma, uncontrolled in 43.2% of cases. Previous
studies have already pointed out that the findings of spirometry may not
be faithfully related to the severity of childhood illness and that
clinical parameters are the most useful for conducting treatment in this
age group27. However, the role of spirometry in the
management of asthma is well established, since it is useful to identify
patients at higher risk due to the presence of obstructive ventilation
defect and a positive response to bronchodilator28.
This response in patients with normal spirometry is an alert to
specialists and may represent an objective parameter of uncontrolled
disease28. In this study, 22.2% of children had
positive responses after using 400 mcg of salbutamol.
This study has some limitations, such as the cross-sectional design, the
difficulty in correlating the sputum pattern with other variables,
especially with the use of drugs such as inhaled or systemic
corticosteroids. The collection of more than one sputum sample from the
same patient, at different times, could confirm the predominant pattern
and possible interferences of the medication.
In conclusion, this study found a predominance of eosinophilic profile
in the sputum of stable asthmatic children, but it also showed that
other cytological patterns may be present, especially in a population of
severe asthmatics.
The study also proved the viability of sputum induction in children with
asthma, representing a safe, effective and tolerant technique that would
be valuable in investigating patients who require specialized care,
contributing to the perspective of individualization. treatment.