DISCUSSION
Despite the low mortality, bronchiolitis has high morbidity. Death by
respiratory failure in bronchiolitis is rare, affecting 5.3 per 100,000
infants under 12 months old in the USA, where resources for intensive
care and research advance and reduce this rate.10Also, the mortality rate was low even in children with comorbidities
(e.g., low weight, young age, and premature birth) and those under IMV
for a long period (i.e., more than seven days).11-13This rate was associated with low breathing patterns in children with
bronchiolitis. However, children with bronchiolitis under IMV and who
progressed to SARS presented increased complications and mortality rates
since it is a viral infection that impairs the respiratory
system.11,13
Two children with low birth weight died in this study; one had
congenital heart disease, and the other had SARS. Although both children
were under IMV, they died due to severe bronchiolitis, which caused
hemodynamic instability.14,15 Similarly, severe
bronchiolitis was previously associated with young and low-weight
children who developed ARF followed by SARS since bronchiolitis may
increase the respiratory pattern by sixfold. 1,13
Younger (i.e., less than six months old) and premature infants presented
severe bronchiolitis with adverse respiratory impairment, needing
ventilatory support. Mechanical factors (e.g., small airway caliber) may
increase airway resistance, which is further increased by the
inflammation and swelling of the airways due to the disease. Also,
immunological factors, such as the weak immune system in younger and
premature infants, may hamper innate immune responses, and these infants
become susceptible to viral infections and require ventilatory
support.16,17
The NIV is one of the initial supportive measures for acute
bronchiolitis, which may progress to IMV in severe cases, especially in
children with comorbidity and low weight. These cases require continuous
positive airway pressure and BiPAP, which may not reverse the
respiratory distress.12 Corroborating this data, one
child in the present study was intubated even after using NIV. However,
a previous study showed that children under early NIV improved their
respiratory condition, requiring only nasal cannula oxygen therapy with
a low flow. 18 Thus, ventilatory support using NIV may
avoid IMV and its complications in most cases.19
The treatment of bronchiolitis depends on its severity since this
disease may impair lung function on the fifth day. Thus, oxygen therapy
is designated and changed to NIV in case of increased severity,
progressing to intubation with IMV in case of NIV failure. In this
sense, the three measures are related, and the inverse process may also
occur (i.e., an extubated patient may need NIV followed by oxygen
therapy in case of improved condition). These measures are commonly
combined with salbutamol, hypertonic solution, and bronchodilators,
especially in children with respiratory distress and requiring
nasogastric tube feeding.4,5
In this study, the risk of severe bronchiolitis caused by RSV was higher
in male than female children, possibly due to differences in lung
structure, airway development, and genetic factors.20The present study corroborated previous studies considering male gender,
congenital heart disease, and young age (from one to six months) as risk
factors for bronchiolitis; these conditions require bronchial washing
and aspiration due to excess mucus.21-23 The
comorbidities with the highest risk for bronchiolitis were congenital
heart disease and bronchopulmonary dysplasia.20
Children younger than 24
months old, with less than 37 gestational weeks, and low weight birth
also presented an increased risk for prolonged hospitalization in
PICU.17,24 Although the hospitalization period was not
associated with aspiration, children under IMV and NIV were hospitalized
for longer than those without IMV and NIV. Even with technological
advances in ventilatory support, which reduced hospitalization costs and
period and support-related lung injury, the most severe cases required
IMV, NIV, and prolonged hospitalization to obtain clinical improvement
and stability.12,24,25,26
In the present study, the hospitalization period ranged from 5 to 15
days in cases requiring IMV or NIV, with a mean of 12 days in PICU and
15.71 days of the total hospitalization period. Also, 94.52% of
children were discharged to the ward, and two were discharged for home
care. In this sense, the hospitalization period was directly associated
with the virus incubation (about four to five days) and factors
increasing the condition severity. Long hospitalization was previously
associated with high costs, emotional burdens, and health-related
issues.21 Parents accompanying the children during
hospitalization missed workdays, affecting their income. In addition,
anxiety was associated with the children condition, which may cause
long-term consequences for the family.21