Discussion
There is substantial variability in the surveillance and management of
children with tracheostomy. Clinical guidelines are lacking in several
aspects of tracheostomy care, including outpatient management of
respiratory infections. Hospitalizations for these patients are lengthy,
costly and common. To our knowledge, this is the first study to describe
the outpatient treatment of respiratory infections, as well as to
examine the impact of hospitalizations on children with long term
tracheostomy.
In this study, we retrospectively analyzed whether hospitalization rates
due to LRTI in patients with tracheostomy were affected by outpatient
treatment methods of either receiving only increased AWC or receiving an
antibiotic in addition to increased AWC. We found that those who
received only AWC did not have significantly higher odds of
hospitalization within 28 days of treatment, compared to those who
received an antibiotic. This data indicates that there may be no
advantage to prescribing antibiotics. Antibiotics can be costly, can
induce bacterial resistance and can have systemic side effects, even in
the case of inhaled tobramycin as renal failure and ototoxicity have
been reported 6-8.
We identified no studies that evaluated the same interventions and
outcome. However a study by Zhu 4 investigated
hospitalizations due to ambulatory care sensitive conditions (ACSCs)
which were defined as conditions for which good outpatient care could
potentially prevent the need for hospitalization or for which early
intervention could prevent complications. They found the most frequent
and costly ACSCs that lead to hospitalization were bacterial pneumonia
and tracheostomy infection. This study, along with our study where we
found that patients called frequently for respiratory concerns and were
treated often for these illnesses, indicates a need to identify optimal
treatments to effectively treat LRTIs at home.
As noted earlier in the study, inhaled tobramycin was the most commonly
prescribed antibiotic. Anecdotally, many parents prefer inhaled
tobramycin due to its localized activity and fewer systemic side effects
such as diarrhea and abdominal upset. In the absence of evidence based
guidelines for treatment of LRTI in this patient population, antibiotic
choice was determined by previous respiratory culture results,
patient/parent preference, accessibility to and availability of the
medication, insurance coverage and affordability. The intravenous form
of tobramycin for inhalation is not widely available in outpatient
pharmacies, with enteral antibiotics often being prescribed in its
place.
Despite minimal data, treatment of LRTI is often based on previous
cultures or most common bacteria cited in the literature (P.
aeruginosa and MRSA)5. In agreement with previous
studies, we found P. aeruginosa to be the most commonly isolated
pathogen on respiratory cultures 9,10. This is in part
due to the tenacious nature of Pseudomonas which strongly adheres to the
tracheal mucosa 9. Though there is conflicting
evidence, several authors have shown MRSA to also be prevalent in
tracheal cultures, second to P. aeruginosa9,10. Nevertheless this was not the case with our
study where S. maltophilia was actually more common than MRSA.
The cystic fibrosis (CF) literature has demonstrated an association
between P. aeruginosa acquisition and increased pulmonary
exacerbation rates, declining lung function and greater mortality11-13, as well as shortened survival in those with
MRSA 14. The acquisition and outcomes of eradication
of P. aeruginosa and MRSA in pediatric patients with tracheostomy
remains unclear though a retrospective study by Russell15 showed that acquisition of P. aeruginosa was
associated with significantly increased odds of readmission for
respiratory tract infections within 12 months of discharge from the
tracheostomy placement hospitalization.
While obtaining routine respiratory cultures is the norm in patients
with cystic fibrosis16,17, there is no evidence
showing the benefit of collecting surveillance respiratory cultures in
healthy patients with tracheostomy. Biofilm is known to develop in
tracheostomy tubes as soon as 7 days after tracheostomy tube change or
initial placement 18 and results in subsequent
bacterial colonization of the airway. Cline et al19showed that bacteria and antibiotic sensitivity can change between
consecutive respiratory cultures and thus use of prior cultures was of
limited benefit for choosing antibiotic therapy in treating
exacerbations. In addition, reports have shown that colonization without
infection is common and there are no good methods for distinguishing
colonization (which may not require treatment) from overt infection that
requires intervention 20,21.
Nevertheless, many practitioners use prior respiratory cultures as a
guide for treatment of LRTI5. However, despite the
prevalence of S. maltophilia in our patients’ respiratory
cultures, trimethoprim-sulfamethoxazole was not prescribed as often as
would be expected. This could be because S. maltophilia may not
have grown on the most recent culture and so was not thought to be the
cause of the current LRTI. We also think it could be due to previous
findings showing that most children with tracheosomy will acquireP. aeruginosa10,15 and would benefit from
anti-pseudomonal targeted therapy. A recent study 22evaluated treatment of S. maltophilia in children with
tracheostomy and acute respiratory illness. They found no difference in
the amount of time to return to respiratory baseline after treatment
targeting S. maltophilia with trimethoprim-sulfamethoxazole
versus those who were also S. maltophilia positive but did not
receive targeted treatment. This study shows there may be no benefit of
targeted treatment of S. maltophilia in this group, but more
rigorous evaluation is needed.
There were several limitations to this study. This is a retrospective
study, so we cannot ascribe causality to interventions for LRTI. Our
sample size was small and does not preclude type II error, i.e., that
antibiotics are effective in reducing LRTI hospitalizations in children
with tracheostomy. Additionally, most of the patients were young and
received a tracheostomy for prematurity and neuromuscular disease.
Further study is required for children over 6 years of age as well as
patients with other indications for tracheostomy.
We accounted for four confounders that we thought most impacted outcomes
including lower odds of hospitalization if patients were recently
hospitalized; however there were other confounders that we did not
evaluate such as socioeconomic status, smoke exposure at home, daycare
or school attendance and home nursing since this data was missing or
incomplete. Cristea et al 23 showed that chronically
ventilated children who lived in lower ZIP code- based annual household
income areas had higher mortality.
Next, several patients also received treatment outside of Riley Hospital
(such as antibiotics for LRTI from primary care provider) and we were
only aware of these treatment episodes if parents called our clinic to
report it. Our study was focused on chronically ventilated patients as
these patients were more likely to be treated solely within our hospital
system compared to patients who were not chronically ventilated,
ensuring that we were less likely to miss any episodes of LRTI. It is
reasonable to assume that we underestimated the number of treatment
episodes given outside of Riley Hospital considering it was easier to
see the local pediatrician than our outpatient clinic for a sick visit
either due to distance or sick visit availability. Similarly, patients
were sometimes hospitalized outside of Riley Hospital. We were only
aware of the hospitalizations if discharge paperwork was sent to us and
so the number of hospitalizations was also likely underestimated. Our
analysis does not account for adherence to the prescribed treatments.
Diagnosis of LRTI lacks consistency owing to various definitions of
infection and treatment recommendations, further complicating decision
to treat with antibiotics 24,25.