Discussion:
In this prospective observational study, we noted that the number of
cases with AVB were higher in the months of November-December 2019. The
common symptoms included rapid breathing, cough, and fever. The common
findings at admission were tachypnea, chest retractions, respiratory
failure, low SpO2, wheezing, and crepitations. RSV and rhinovirus are
most commonly detected. The extra-pulmonary manifestations were
described in 25% cases in form of encephalopathy, transaminitis, shock,
AKI, myocarditis, MODS, and ARDS. More than 1/3rdcases needed PICU admission and common treatment included oxygen support
(nasal prong oxygen, CPAP, of HFNC), mechanical ventilation,
nebulization (3% saline, adrenaline, and salbutamol), vasoactive drugs,
and steroids. One-third cases also received intravenous antibiotics. The
mortality rate observed to be 8%.
The impact of AVB on the health of young children is huge and
approximately 2-3% of infants require hospitalization due to
AVB4. Characteristically, in a winter month a child
presents with 2-4 days history of low-grade fever, rhinorrhea, nasal
congestion; and symptoms of lower respiratory tract involvement (cough,
tachypnea); increased respiratory effort (grunting, nasal flaring, and
intercostal, subcostal, or supraclavicular retractions); and inspiratory
crackles and expiratory wheezing on auscultation4,10.
Despite the high burden of disease, there is lack of effective treatment
for AVB. None of the commonly practised modalities shown to shorten the
disease course or hastens the resolution of symptoms of AVB leaving the
clinicians to go for supportive therapy in form of heated humified
oxygen, adequate hydration, and respiratory monitoring for improvement
or worsening. With supportive treatment, majority of infants with AVB do
well. The American Academy of Pediatrics published clinical practice
guidelines based on Grading of Recommendations, Assessment, Development
and Evaluation (GRADE) system to standardize the diagnosis and
management of AVB18. As per the guidelines, the
suspicion of AVB should be based on the history and physical
examination. There is no need of routine radiographic, laboratory
studies, and viral testing. The supplemental oxygen is needed if
oxyhemoglobin saturation (SpO2) falls below 90%. Intravenous or
nasogastric fluids to be administered to maintain adequate hydration.
Epinephrine, short-acting β2-agonists, systemic glucocorticoids, chest
physiotherapy, and antibiotics are not recommended for the treatment of
AVB. Nebulization with hypertonic saline may be used as it improves
symptoms of mild-to-moderate AVB, if length of stay is >3
days18.
Due to tertiary care referral hospital, commonly the infants with severe
illness are referred with respiratory failure, higher rates of
extra-pulmonary complications (25%), more cases required PICU admission
(36.4%), and mechanical ventilation (23%), vasoactive drugs (14%);
and had higher mortality (8%).
PICU admission is needed in 15-25% of children with AVB. About 25-40%
of those admitted to PICU require endotracheal intubation and mechanical
ventilation which is associated with various complications including
ventilator induced lung injury, infection, airway trauma, vocal cord
dysfunction, need for prolonged sedation, and overall a financial burden
to the family19-22. Various non-invasive modes of
oxygen delivery are being increasingly used including CPAP, HFNC,
non-invasive positive pressure ventilation (NPPV), and bilevel positive
airway pressure (BiPAP) which may obviate the need for invasive
mechanical ventilation and complications related to
it23-27. The infants deteriorating on non-invasive
modes of oxygen delivery required intubation and mechanical ventilation
because of apnea, severe lower airway disease, or ARDS and usually need
a shorter mechanical ventilation (<5 days)3,
28. Appropriate sedation and analgesia should be provided to infants
with AVB. There is substantial variability in diagnosis and management
of infants with AVB in different PICUs22.
In index study, 36.4% cases needed PICU admission.
Underlying comorbidity; presence
of chest retractions, respiratory failure, and lower oxygen saturation
at admission; presence of shock; and need of mechanical ventilation were
independent predictors of PICU admission on multivariate analysis.
In AVB, the use of antibiotics does not lead to change in course or
outcome and are not routinely recommended4,18. Despite
these facts, antibiotics has been used in AVB inappropriately. Papenburg
et al29 noted that about 25% infants with AVB were
given antibiotics, 70% of them had no documented bacterial
co-infection, and 38% received macrolides. Therefore, efforts are
needed to reduce inappropriate and unnecessary use of antibiotics in
AVB.
With the availability of molecular techniques, it has been possible to
identify viruses causing AVB. The most common viruses identified are RSV
(50-80%), rhinovirus (5-25%), PIV (5-25%), hMPV (5-10%), coronavirus
(5-10%), adenovirus (5-10%), and influenza
(1-5%)4,11,30,31. The proportion of virus causing AVB
differ according to geographical location and time of the year. The
clinical features of AVB caused by different viruses are generally
indistinguishable. However, it has been noted that AVB caused by
rhinovirus may be less severe and associated with shorter duration of
hospitalization than RSV4,32. Also, there are not much
differences in response to medical treatment among infants with AVB
caused by different viruses4. The reported rates of
co-infection varied widely among different studies ranging from 6% to
more than 30%4,32,33. Few studies noted greater
severity of disease, longer hospital stay, more severe hypoxemia, and
greater risk of relapse in children with
co-infection32,34,35; whereas, other studies showed no
difference on disease severity and outcome in those with
co-infection33,36-38. In index study, atleast one
virus was isolated in 74% cases with RSV and rhinovirus as commonest.
One-fifth cases had co-infection with >1 virus.
However, isolation of virus or
co-infection was not associated with any differences in clinical
features, complications, treatment, PICU needs, and outcome.
The strengths of this study include prospective study with large sample
size. All the enrolled cases underwent viral testing which is important
to determine etiology but did not have much significance in determining
disease severity, prognosis, and short-term outcome. The details of
treatment, intensive care needs, and outcome has been described. The
predictors of PICU admission were determined. The limitations included
single centre study and lack of long-term follow-up.