Discussion:
Our study demonstrates that a RT-driven HFNC management protocol can be
safely implemented for pediatric critical asthma patients in the PICU.
When used concurrently with a continuous albuterol weaning protocol, it
can reduce HFNC duration, PICU LOS and hospital LOS. This was done
without increased use of NIV and IMV or a sustained increase in 7-day
PICU and hospital readmission rates.
The use of HFNC has become more common in PICUs over the course of the
last two decades, and its efficacy in other similar disease processes
such as bronchiolitis has been well established (23,24). In critical
asthma, it has been shown to be safe, but limited data has not shown
significant clinical benefits or decreased length of stay with its use
(25,26). Many physicians utilize HFNC as a delivery mechanism for
aerosolized medications such as continuous albuterol, which is shown to
be effective at lower levels of HFNC (27). It is possible that despite
clinical improvement, patients remained on HFNC to facilitate continuous
albuterol delivery, which could help explain why there was not a
decrease in duration of HFNC in PDSA 3 and 4.
There are other therapies used in the treatment of pediatric critical
asthma aside from inhaled beta agonists. Steroids have long been a
mainstay in treatment (28,29). Other therapies, such as magnesium
sulfate, aminophylline, and terbutaline have had mixed results (30-32),
and because of this, institutions tend to have different protocols for
management of critical asthma. In our study, there was no increase in
the utilization of other adjunct medications which might affect our
outcome measures. It would be useful to have more definitive guidelines
on the use of adjunctive therapies in pediatric critical asthma in the
future to improve outcomes.
There is concern that with widespread use of HFNC in other disease
processes, hospitalization costs have increased (7,8). In many
hospitals, HFNC is used exclusively in the PICU which could be a driver
of the increased cost. Concerns have been raised regarding the
environmental impact associated with increased use of HFNC related to
carbon emissions (33). While we recognize HFNC as an important
respiratory support modality in many disease processes, it is important
to be judicious in its use. Often, patients in respiratory distress are
placed on HFNC in the emergency department as it is a quick and
relatively easy way to provide respiratory support. However, a patient
may rapidly improve in the PICU and no longer require HFNC treatment,
but this goes unrecognized by the care team because of higher acuity
patients, which leads to PICU and hospital stays, higher costs and
increased environmental impact. Standardization of care, such as
RT-driven HFNC management protocols, can help mitigate these issues.
There was no increase in adverse events in patients with critical asthma
with the implementation of the HFNC management protocol and its
subsequent modifications. During PDSA 1, there was a small but
statistically significant increase in PICU and hospital readmission with
return to baseline low levels in subsequent PDSA cycles. The rate of IMV
decreased during the study. A similar study on the utilization of a HFNC
management protocol in patients with bronchiolitis showed a similar
pattern (12). This could be due to increased provider comfort with
utilizing HFNC and other noninvasive respiratory support modalities or
related to improvement in the care of patients with critical asthma in
general. While previous studies have shown that HFNC decreases IMV rates
in other disease processes such as bronchiolitis (23,24), this is less
clear in critical asthma.
This study has several limitations. This was a single center quality
improvement project, which may limit its generalizability to other
centers that have different practices for treatment of critical asthma.
While the PASS is a validated measure, the Riley Hospital Respiratory
score is not, though it is similar to other scoring systems used in
other studies (34-36). Like many other PICUs, RT staffing was limited at
times which may have led to increased length of HFNC due to other more
acute needs. In addition, other factors can influence PICU and hospital
LOS, such as ward bed availability, nurse staffing, and social issues
that prevent timely discharge. These factors are difficult to monitor
and are outside the scope of this study. Finally, our protocol did not
include a standardized criteria to start HFNC. Given the national trend
of trading conventional oxygen therapy via facemask with HFNC in
pediatric critical asthma (37), future interventions can aim to
standardize the HFNC initiation in emergency rooms and PICUs.