Bronchiolitis is the most common lower respiratory tract infection in patients under two years of age and the leading cause of hospital admission for those under six months of age .¹ This past winter saw a huge rise in pediatric respiratory illness in North America as well as an increased admission rate for children with bronchiolitis.² There is a wide spectrum of severity of illness as well as a huge variation in practice in treating these children.³ Complicating the approach to bronchiolitis further, the definition of bronchiolitis varies across guidelines, and while about 60 percent of bronchiolitis is caused by respiratory syncytial virus, 20 percent is caused by rhinovirus, which confers a 59 percent risk of developing asthma.⁴ While most children with bronchiolitis can be diagnosed without any workup and will improve with simple interventions and be discharged home, we need to know when to worry about the few who will require complex care, and this is sometimes challenging to sort out.

The Clinical Diagnosis

Bronchiolitis is a clinical diagnosis based on patient age, time of year, and clinical presentation. The typical patient with bronchiolitis is a child under 12 months of age who, during fall and winter months in northern climates, has a two- to three-day upper-respiratory-tract-infection prodrome and then develops symptoms of a lower respiratory tract infection with increased work of breathing, crackles, and wheezes, as well as poor feeding.⁵ It is important for clinicians and families to understand that acute symptoms usually last for approximately 10 days, but that the cough can last up to three weeks. Neonates may present with apnea and/or cyanosis.⁶

During the initial ED assessment, it can sometimes be difficult or even impossible to distinguish bronchiolitis from upper respiratory infection with asthma and bronchiolitis from bacterial pneumonia, as their clinical presentations overlap.⁷ Clinical presentations that suggest an alternative diagnosis to bronchiolitis include prolonged wheeze (three weeks or more), failure to thrive, recurrent feeding issues, choking with feeds, previous bacterial pneumonia, and the critically ill patient.⁵ Multiple wheezing episodes at any age increases the likelihood of asthma.⁴ The diagnosis of asthma can be tentatively made in otherwise healthy children as early as 12 months of age, using the following criteria: two or more episodes of wheezing, emergency department (ED) presentation of wheeze needing treatment, reversibility of respiratory distress after therapy, or first-time wheeze with response to therapy.⁸ The early diagnosis of asthma is important because literature suggests that a subset of patients with bronchiolitis develop abnormal lung function by the age of five years and long-term lung disease, and that this may be prevented with three-month courses of corticosteroids following each acute exacerbation.⁹ Bacterial pneumonia, which can occur concurrently with bronchiolitis, can be distinguished from bronchiolitis by the following clinical findings: high fever, toxic appearance, absence of wheeze, and unilateral chest findings.¹⁰

Pediatrics

Children with bronchiolitis are often over-investigated in EDs in the U.S.¹¹ For a child who presents typically, no investigations are necessary. The American Association of Pediatricians (AAP) Clinical Practice Guideline for the Management and Diagnosis of Bronchiolitis states: “clinicians should diagnose bronchiolitis and assess disease severity on the basis of history and physical examination. Clinicians should not routinely order laboratory and radiologic studies for diagnosis.”¹² The chest Xray (CXR) findings of bronchiolitis are often nonspecific patchy infiltrates and hyperinflation that can often be misinterpreted as consolidation and lead to inappropriate antibiotic use.¹³ Routine CXR for bronchiolitis is not recommended, as this often leads to unnecessary use of antibiotics.⁵ One study found that pediatric emergency physicians over-read CXRs at a rate of five to one compared to radiologists.¹⁴ Testing for respiratory viruses should be reserved for neonates, immuno-compromised patients, those with a prolonged fever, and those with atypical presentation.¹⁵

It is incumbent upon the ED physician to identify high-risk bronchiolitis patients who should be considered for admission to hospital. Factors considered high-risk in patients with bronchiolitis include heart rate greater than 180, respiratory rate greater than 70, awake persistent saturations less than 90 percent, age less than two months, prematurity less than 32 weeks, chronic lung disease, cyanosis or history of apnea, hemodynamically significant congenital heart disease, immunodeficiency, and neuromuscular disease.¹⁶ In the decision of whether or not to admit a child with bronchiolitis, it is important to understand that 30 percent of hospitalized infants receive no therapies needing hospitalization.¹³ Hospitalization for otherwise healthy children with mild bronchiolitis has been described as “expensive baby-sitting.”¹⁷ Remember that bronchiolitis symptoms usually peak around days three to five. If the patient presents on day two, you can expect the patient may get worse before they get better. This should be factored into your disposition decision.

Bronchiolitis is a self-limited disease, which can be managed at home with supportive care in the majority of cases. Parental education is vital. Explain the duration of illness and dynamic nature of symptoms. Explain why drugs are ineffective. Suggest frequent feeding (every two hours) to maintain adequate hydration. Explain the red flags of poor feeding and behavioral change as reasons to return.

Medications for Children

Pharmacotherapy is generally ineffective in children with bronchiolitis. There is no compelling evidence that bronchodilators, steroids, or epinephrine improves outcomes. While nasal suctioning is frequently employed with the goal of improving feeding in the child with nasal obstruction, its efficacy is unknown. One large bronchiolitis study suggests that in-hospital nasal suctioning significantly increases hospital length of stay.¹⁸ Given that pharmacotherapy and nasal suctioning are not backed by strong evidence, management should concentrate on three things: maintaining adequate volume status/feeding, oxygenation, and airway support.

Most children with bronchiolitis and volume depletion can be repleted by increasing the frequency and length of feeds. Those that have evidence of severe dehydration or require admission to hospital for another reason may require intravenous or nasogastric volume repletion.

Many healthy infants exhibit typical transient oxygen-saturation dips during sleep. A study of children discharged from the ED with bronchiolitis showed that 62 percent desaturate during sleep, some with prolonged desaturations, and the outcomes were the same regardless of whether desaturations were detected or not.¹⁹ There is in-hospital evidence to suggest that continuous oximetry may prolong length of stay,²⁰ particularly if staff react to normal transient dips in oxygen saturation or changes in heart and respiratory rates with interventions such as restarting oxygen therapy. The rationale for respiratory monitoring is to detect episodes of apnea requiring intervention. In a study of 691 infants under six months of age, only 2.7 percent had documented apnea, and all had risk criteria of either a previous apneic episode or young age under one month or under 48 weeks post-conception in premature infants).⁵ A randomized controlled trial (RCT) of 161 bronchiolitis inpatients at four U.S. hospitals randomized patients to continuous oximetry versus spot checks with vital signs and found no difference in outcomes. Continuous respiratory monitoring is indicated for high-risk patients in the ED, primarily to detect apneic episodes, but is not necessary for the vast majority of patients with bronchiolitis.²¹ The majority of children with bronchiolitis require only intermittent “spot check” oximetry. Use continuous oximetry selectively in those with marked respiratory distress and/or requiring supplemental oxygen.

High-flow nasal cannula (HFNC) for bronchiolitis has gained popularity in recent years after a multi-center RCT in 2018 showed lower rates of treatment failure in bronchiolitis patients treated with HFNC in a non-intensive-care setting compared to standard nasal cannula with a number needed to treat (NNT) of 9.22 However, with the increasing popularity of HFNC for children with bronchiolitis, there has been a doubling of ICU care for bronchiolitis in the U.S over the past two decades, independent of age, co-morbidities, and hospitalization rates.²³ This increase in ICU admissions corresponds to the surging rate of HFNC use. The main impetus for HFNC in hospital wards is to offload the ICU and to reduce ICU length of stay, however the evidence does not support this outcome. Two RCTs comparing early HFNC to rescue HFNC found the same rate of ICU transfers, that 75 percent of patients needed no escalation of care, and that HFNC costs 16 times more than standard nasal cannula.^24,25 These studies suggest that early HFNC provides costly therapy to many children who will not benefit and that HFNC should be used as rescue therapy for patients failing standard treatment, rather than initiated early. While there are no evidence-based clear guidelines on the indications for HFNC in bronchiolitis, reasonable indications include: failure of standard low-flow oxygen therapy (awake O2 saturations less than 90–92 percent), increasing oxygen requirements above 40 percent fraction of inspired oxygen, increasing lethargy, and persistent severe respiratory distress. Failure of HFNC is usually an indication for non-invasive ventilation (with continuous positive airway pressure) and ICU admission.

Less is More

Remember that for the vast majority, less is more. A workup is usually not indicated, pharmacotherapy is generally ineffective, spot check oximetry rather than continuous oximetry is usually adequate, and supportive care with simple nasal-prong oxygenation when indicated, HFNC only for treatment failures, increased feeding, and good parent education is usually all that is required.

Dr. Helman is an emergency physician at North York General Hospital in Toronto. He is an assistant professor at the University of Toronto, Division of Emergency Medicine, and the education innovation lead at the Schwartz/ Reisman Emergency Medicine Institute. He is the founder and host of Emergency Medicine Cases podcast and website.

References

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