Discussion
Synthesis of the results
The present study showed that (1) the moderate use of accessory muscles,
nutritional support and RR ≥ 70/min or < 30/min or apnea are
associated (OR=1.5), from virtually no association (OR=1.0) to a
significant positive association (OR=2.6) with the LOFR and (2) the new
severity scale proposed the HAS and other known factors such as oxygen
support appeared to be related to LOS in this work and (3) the ACT+
group were older and heavier and had a less severe clinical condition at
admission compared to the ACT- group.
Adequate nutrition
One major difficulty for this work was to define what constitutes
adequate infant feeding. The current guidelines agree on the importance
of maintaining adequate feeding during an episode of bronchiolitis, but
a clear definition of the nutritional monitoring and management is
lacking 3,15. We chose to define adequate feeding
according to the ratio of food intake to basal metabolic rate (BM), with
a ratio ≥0.7 indicating adequate nutrition based on the latest
Recommended Dietary Allowances (RDAs) of the French population and the
European guidelines on parenteral nutrition 11.
Previous studies including children hospitalized for bronchiolitis in
general ward and pediatric intensive care unit (PICU) proposed the use
of different ratios (namely 0.8 and 0.9) to detect undernourished
children based on expert committee 16,17. Furthermore,
the WHO recommends exclusive breastfeeding for children up to 6 months
of age, and dietary diversification starts at about 6 months of age18,19,20. As these two forms of feeding are not
suitable for mL measurement, we did not include 117 breastfed infants
(24.4%) and 93 who had started diversification (19.5%), which could
have impacted our results.
The HAS proposes to consider children with bronchiolitis feeding
difficulties from a cut-off of <50% of the habitual on three
consecutive intakes 5. According to this definition,
almost all children who had feeding difficulties on admission received
feeding support during the hospital stay (namely 31% and 28%). This
proportion is much lower than others studies (86% and 82%)13,21 and could be explained by the higher objectivity
of this cut-off value, compared to the oral parental reporting of
feeding difficulties in these studies.
Characteristics of the study
sample
The comorbidities previously identified as predictors of higher LOS are
congenital heart disease with shunt, chronic pulmonary disease (such as
cystic fibrosis), immune deficiency, neuromuscular disease
(polyhandicap, Down syndrome), preterm birth (<36 weeks of GA)
and corrected age <2 months 5,13,22. We did
not find any association between them and prolonged LOS, possibly
because they were not highly prevalent (1.4 to 3.5%), except for
prematurity (14.4%). Furthermore, compared to Gajdos et al.13, our lower proportions of infants exposed to
parental smoking (7% vs. 27%) or with atopic background (20% vs.
40%) could be due to the absence of systematical reporting in the
admission or medical records.
Respiratory distress
assessment
The median Silverman-Anderson score was 2/10 at admission in the present
study, corresponding to a mild respiratory distress. This could seem
quite surprising for a cohort of hospitalized children and contradictory
compared to the HAS severity scale, who mostly rated our cohort as
moderate to severe bronchiolitis (39.9 and 51.8% respectively). These
results can be explained by the important variability of symptoms during
the beginning or the bronchiolitis course, called the critical period by
Florin et al 6. As most infants are hospitalized
during the critical period, the clinical variability over 24 hours is
important and may lead to inconsistencies in the clinical evaluation
scores. Secondly, inter-observer reliability of the Silverman-Anderson
score has been shown to be questionable between different caregivers23.
The new severity scale (latest French
guidelines)
To our knowledge, this study is the first to investigate the
relationship between this new severity scale proposed by the HAS and the
hospitalization course of these children. It appeared that this scale
was associated with the LOS in the present study, but could be
questioning, especially since the median respiratory distress score was
low. It is worth noting that the Silverman-Anderson score only rates the
respiratory distress, whereas the severity scale includes more items,
such as general condition and feeding. Secondly, it is usually advised
to measure the infant’s RR over a complete minute because of the
variability of this parameter. However, in the context of a
retrospective study, the RR could have also been rated according to the
ED’s monitor, which is usually higher and more variable, than the
one-minute measure. In addition, assessing the general condition of a
children is highly subjective, which could explain the discrepancies
observed in the severity ratings. Finally, RR and HR are lower during
sleep, which may influence the use of accessory muscles24. Unfortunately, the children state of arousal was
not reported in the medical charts investigated.
ACT
In daily hospital practice, physiotherapists usually perceive the
indication for ACT in the mildest infants with bronchiolitis. Several
expert’s opinion has hypothesized that children with mild or too severe
bronchiolitis would not benefit for in-hospital ACT25. However, ACT referral is largely based on the
subjectivity of the physician’s prescription and on the
physiotherapist’s assessment. In our cohort, 63% of the infants
received regular ACT during their hospital stay, without any clinically
relevant significant difference between them, and those who did not.
These results are consistent with the previous evidence on that topic
since the studies that observed a benefit for ACT in children with acute
viral bronchiolitis included children with a moderate profile26. Clear and objective indications for ACT referral
should be identified, as well as the profiles of the children that would
eventually have a positive response to ACT. These two elements seem
unavoidable to get rid of a one size fits all approach that seem
inappropriate, as well as an approach only based on subjective features.