Abstract
Ventilator associated respiratory tract infections (VARTI) are among the
most common indications for hospitalization among children with chronic
respiratory failure requiring at-home ventilation. This review aims to
provide an overview of the key clinical features, diagnostic approaches,
and management strategies for home VARTIs while highlighting the
challenges in diagnosis and management.
Ventilator associated respiratory tract infections (VARTI) including
tracheitis and lower respiratory tract infections are among the most
common indications for hospitalization among children with chronic
respiratory failure requiring at-home ventilation 1.
Ventilator associated tracheitis is an infection of the trachea that can
result from bacterial colonization of the endotracheal tube, the
tracheostomy site or from aspiration of respiratory pathogens. Altered
upper airway defenses in these patients further increase the likelihood
of pathogen transmission to the lower airways resulting in lower
respiratory tract infections (LRTI). LRTI is an infection of the bronchi
or the lungs that can be caused by viruses, bacteria, or fungi.
Bacterial pneumonia is the most common reasons for hospital admission in
children with tracheostomy, accounting for over 2,000 admissions and
$100 million in U.S. hospital charges in 2009 1.
These numbers are likely increased with advances in biotechnology and
care of patients needing long-term mechanical ventilation. The
prevalence rates of VARTI or individual tracheitis and LRTI rates are
unknown as the definitions of these disease processes are not
standardized in children receiving home ventilation. Ongoing limitations
of diagnostic tools, as well as patients’ access for evaluation and
diagnostic testing add to the challenges of diagnosing VARTI. The Center
for Disease Control (CDC) criteria for diagnosing tracheobronchitis are
primarily designed for national surveillance rather than individual
patient diagnosis and does not provide clarity for LRTIs (CDC). Chest
radiographs, auscultation, and sputum production are unreliable
indicators, and tracheal aspirate cultures may not reliably distinguish
between colonization and infection 2,3. These
uncertainties and lack of standardized protocols in a patient population
with high risk of clinical deterioration understandably result in
variable clinical practices.
Families of children with medical complexities, who are chronically
ventilated, may call their clinician rather than bring their child to
the clinic or hospital, because of the large transportation burden on
these families 4. These calls to the physicians may
result in over diagnosis and unnecessary antibiotic treatments. This is
reported to be common occurrence in pulmonology, complex-care patient
clinics and may contribute to increased diagnosis and treatment of VARTI4. Physicians may also elect to admit patients to
avoid additional outpatient evaluation to ease the hardship for the
patients and caregivers. It is therefore crucial to have timely
identification and accurate diagnosis of these infections to provide
appropriate therapy and prevention of further complications and
morbidity. This review aims to provide an overview of the key clinical
features, diagnostic approaches, and management strategies for home
VARTIs while highlighting the challenges in diagnosis and management.
Several factors contribute to the increased risk of respiratory tract
infections in children with tracheostomy tubes. The upper airway’s
defense mechanisms, including nasal filtration, warming, and
humidification of inspired air, are compromised 5.
Tracheostomy tubes bypass the nasal cavity and reduce the effectiveness
of these defense functions, leading to increased susceptibility to
infections. Additionally, tracheostomy tubes can cause damage to the
tracheal mucosa, impair cough effectiveness and mucus clearance, and
create an environment conducive to the formation of biofilms, which
protect bacteria and contribute to antibiotic resistance6. Other risk factors for respiratory infections in
tracheostomy-dependent children include underlying medical conditions,
difficulty swallowing and aspiration, and the use of certain medications
such as proton pump inhibitors 7. Children with
tracheostomy tubes often develop a diverse range of bacterial
colonization in the trachea, including multi-drug resistant pathogens.
Viral respiratory infections, although less studied, are also common in
this population, with the same viral pathogens that are present in
children without tracheostomy.
With the varied consensus of VARTI, most clinicians consider a
combination of symptoms that indicate a possible infection in the
respiratory tract including the following 8:
- Systemic findings including fever, chills, malaise, fatigue
- Change in ventilator settings, oxygen requirement from baseline and
respiratory symptoms such as increased respiratory rate, dyspnea, or
hypoxemia
- Increased secretions, sputum production, sputum color or consistency,
purulent or foul-smelling discharge, hemoptysis, or blood-streaked
sputum
- Increased cough, wheezing, chest pain, concern for aspiration
- Localized pain or tenderness over the tracheostomy site
- Altered mental status, confusion, or agitation
A retrospective single center review of encounters found that bacterial
tracheostomy associated respiratory tract infections was significantly
associated with a chest radiograph consistent with bacterial pneumonia,
a positive tracheal aspirate culture, higher white blood cell count, and
change in oxygen requirement. Patients diagnosed with VARTI did have
more total abnormal studies documented suggesting a combination of above
listed factors played a role in their diagnoses 4.
Additional factors generally considered by physicians include: history
of exposure to a sick household contact, recent infections, vaccination
status and other comorbidities. Recently, artificial intelligence
modeling has been used in few adult studies to identify patients at risk
of developing infection and with advances in the analysis of patient
data can be considered in the future and may help with accurate
definition of VARTI.
Despite the obvious practical difficulties, a thorough clinical
evaluation, including a detailed history, physical examination, and
assessment of respiratory parameters, are still essential for
identifying possible tracheitis and LRTIs. Laboratory diagnostics can
include complete blood count (CBC), erythrocyte sedimentation rate
(ESR), C-reactive protein (CRP), procalcitonin, blood gas analysis.
Tracheal cultures (collecting tracheal secretions or sputum samples for
microbial culture and sensitivity testing and viral panel testing can
help identify the causative organisms and guide appropriate
antimicrobial therapy. Imaging studies may include chest X-ray (CXR),
which can show signs of pneumonia or atelectasis, or other modalities
such as ultrasound or computed tomography (CT) scan, depending on the
availability and indication. These tests have utility to help identify
the likely causative agent and the extent of inflammation and
respiratory changes in the child.
There is significant variability in the way tracheal cultures are
obtained, processed and in the interpretation of results. Currently
there is no gold standard for when microbiologic work up is needed.
There is a lack of epidemiologic understanding of organisms expected to
be isolated during true VARTI or during the periods of wellness2. Culturing tracheal aspirates does not effectively
distinguish between infection and colonization but can still be helpful3,9. Review of recent and previous tracheal aspirate
cultures identifying the same microorganisms may suggest ongoing
colonization rather than active infection. Although it is non-invasive,
obtaining a culture still poses significant hardship for the caregivers,
at times requiring patient to be evaluated in multiple facilities
increasing their risk of infection 2.
The prevention of VARTI involves strict adherence to infection control
measures, such as hand hygiene, aseptic technique, and proper care of
the ventilator circuit and humidifier 10. Providing
age-appropriate vaccinations including but not limited to pneumococcal,
COVID-19 and influenza vaccination is also crucial for prevention of
infections. There has been also significant debate on the best treatment
and management options of VARTI in this population group. It is hard to
decide when to start antimicrobial treatment especially when there is
any growth of bacteria from these cultures. The longer the exposure to
healthcare environments and ventilation the higher the likelihood for
patients to have colonization, and colonization with multi-drug
resistant microorganisms. Repeated excessive or unnecessary antibiotic
treatment courses can create more resistance and side effects.
Most physicians agree that in bacterial tracheitis patients may have
change and increase in secretions with no significant changes in their
oxygen requirement or ventilation parameters. They may have fevers, and
these are usually not persistent and if a chest radiograph is obtained
it does not show a new pulmonary infiltrate. If feasible, a tracheoscopy
will also help with the diagnosis 5. These patients
may have viral infections as well. In addition to evaluation of sick
household contacts and viral testing, especially for RSV, influenza and
SARS-CoV-2 should be considered. Bacterial infections could follow these
viral infections and may cause secondary fevers and further changes in
tracheal secretions and respiratory parameters.
Antimicrobial treatment is ideally guided by prior cultures while a
new one is obtained. If a culture is not obtained amoxicillin treatment
can be considered. A typical treatment for tracheitis can be limited to
five days and for LRTIs this duration could be extended to seven days.
If patient is clinically worsening and cultures and radiographs were not
obtained tracheal aspirate cultures and chest radiographs should be
obtained. Blood cultures should be considered especially in patients
with systemic inflammatory symptoms who are not improving on initial
empiric treatment. Treatment should be reevaluated weighing previously
identified pathogens, history of exposure and overall clinical status.
Treatment should not be started or continued without appropriate
assessment of the patient.
Available previous cultures could be again used to guide the clinician
for possible colonization and if treatment is needed to understand the
antimicrobial susceptibility patterns of the detected microorganisms.
Targeted treatments should start as soon as culture results are
available. Any additional risk factors including the possibility of
aspiration or pulmonary toilet changes need to be addressed as these may
be causing the infection.
There are several local management guidelines for patients with
home-care ventilation addressing supply needs and required education for
caregivers but the diagnostic criteria and required laboratory and
radiographic evaluation to guide therapy, including duration, are mainly
based on expert opinion or extrapolated from data for
ventilator-associated infections in inpatient settings. More research is
needed to further characterize the specific nuances (and its range of
variation) of pediatric patients with at-home ventilation.
With the advent of quality improvement science, implementation of
standardized criteria for testing and treatment guidelines have shown
that decrease in antibiotic use and resource utilization can be safely
achieved among children requiring mechanical ventilation. More
widespread use of these novel approaches are needed.
Home mechanical ventilation is increasingly used in children with
chronic respiratory insufficiency, but data on adverse events are
limited17. A small study has shown that incidence of
emergencies is low17 but nonetheless life-threatening,
and most could be handled at home (including VARTIs) if both caregivers
and providers are adequately prepared.