4-DISCUSSION
This randomized controlled study
involving children aged between 1 and 24 months diagnosed with moderate
and severe bronchiolitis requiring supplemental oxygen determined that
HFNCO therapy provided a notable improvement in HR, RR, and CRS over
time compared with LFO therapy. This treatment modality offers a heated,
humidified, and high-flow oxygen concentration regardless of the
patient’s effort;24 additionally, it optimizes the gas
exchange by decreasing dead space volume and maintaining mean airway
pressure.24,25 The improvement in mucociliary
clearance,25 with increased alveolar ventilation,
could positively affect high HR and RR baseline values at admission.
Assessing the disease severity is essential for the clinical management
of patients and clinical research. Although many scoring scales exist in
the literature, there are conflicting results regarding the effect of
HFNCO therapy on CRS.11,14,15 Those contradictory
outcomes might be associated with variable clinical score systems used
in studies. Because of the presence of many care providers for these
patients, we used the CRS reported by Liu et al.,19 an
excellent inter-rater agreement (82-88%), to minimize evaluation bias.
However, comprehensive studies focusing on valid and reliable clinical
tools involving objective parameters are needed.
A recent study conducted in children with moderate-to-severe
bronchiolitis found no notable difference in the length of oxygen
requirement and LOS between therapy groups, suggesting that early use of
HFNCO does not modify the underlying disease
process.13 Another randomized, controlled study
demonstrated a lower rate for escalation of care in HFNCO therapy but no
evidence for shorter LOS and the length of oxygen
requirement.12 Similar to these studies, our secondary
results showed a comparable LOS and a lower rate for escalation of care
in HFNCO therapy. Surprisingly, we determined that HFNCO therapy might
shorten the length of oxygen requirement. While many studies showed no
differences in the length of oxygen
requirement,12,13,27 a study conducted in the ICU
suggested that children treated with HFNCO had a shorter duration of
oxygen than those treated with LFO.28 Besides, we note
that secondary results of trials should be assessed carefully because of
the power analysis calculated for primary outcomes. In our study, we
administered HFNCO, at a flow rate of 2 L*kg/min, to the patients
admitted to the general ward and did not identify any severe AEs.
Although recently published reports did not determine any severe
AEs,10-13,26,28 critical air leak syndrome has been
described in children treated with HFNCO.29 Therefore,
HFNCO therapy, a relatively new mode of respiratory support and
increasingly being used, may be performed by closely monitoring the
patients’ clinical status.
This study had some limitations. First, it was performed in a single
center, and we could not reach the number of participants calculated
with the power analysis because of the financial support problem.
Although we used effect size for each of the primary outcomes, the
generalizability of the recommendations reduced. Second, we did not
blind the allocation of oxygen therapies to introduce the risk of
performance bias. Finally, the patients were not allocated to receive
therapy in a ratio of 1:1. Therefore, the results may have been affected
by this diversity.
One of our trial’s strengths was using a clinical scoring system for
children with bronchiolitis, a valuable tool for monitoring the clinical
severity of bronchiolitis. Although there may be a potential bias in any
clinical scoring system, CRS used in this study has been identified to
have an excellent inter-observer agreement. Second, we performed the
parent interview questionnaire by contacting parents 15 days after
discharge to increase the accuracy of the results for each treatment
arm.
In conclusion, HFNCO may provide enhanced respiratory support with a
notable improvement in HR, RR, and CRS than LFO. Comprehensive studies
are needed to assess the clinical efficacy of HFNCO therapy.