INTRODUCTION — Bronchiolitis, part of the spectrum of lower respiratory tract diseases, is a major cause of illness and hospitalization in infants and children younger than two years. The treatment, outcome, and prevention of bronchiolitis will be reviewed here.
The epidemiology, clinical features, and diagnosis of bronchiolitis and the treatment of recurrent virus-induced wheezing in young children are discussed separately. (See "Bronchiolitis in infants and children: Clinical features and diagnosis" and "Treatment of recurrent virus-induced wheezing in young children".)
DEFINITION — For the purposes of this topic review, bronchiolitis is broadly defined as a clinical syndrome of respiratory distress that occurs in children <2 years of age and is characterized by upper respiratory symptoms (eg, rhinorrhea) followed by lower respiratory (eg, small airway/bronchiole) infection with inflammation, which results in wheezing and or crackles (rales). Bronchiolitis typically occurs with primary infection or reinfection with a viral pathogen, but occasionally is caused by bacteria (eg, Mycoplasma pneumoniae). In young children, the clinical syndrome of bronchiolitis may overlap with recurrent virus-induced wheezing and acute viral-triggered asthma. The diagnosis of bronchiolitis, virus-induced wheezing, and acute viral-triggered asthma are discussed separately. (See "Bronchiolitis in infants and children: Clinical features and diagnosis", section on 'Diagnosis' and "Role of viruses in wheezing and asthma: An overview" and "Asthma in children younger than 12 years: Initial evaluation and diagnosis" and "Asthma in children younger than 12 years: Initial evaluation and diagnosis", section on 'Respiratory tract infections'.)
SEVERITY ASSESSMENT — Consensus definitions for severe bronchiolitis are lacking. In general, we consider severe bronchiolitis to be indicated by any of the following:
●Persistently increased respiratory effort (tachypnea; nasal flaring; intercostal, subcostal, or suprasternal retractions; accessory muscle use; grunting) as assessed during repeated examinations separated by at least 15 minutes
●Hypoxemia (SpO2 <95 percent); SpO2 should be interpreted in the context of other clinical signs, the state of the patient (eg, awake, asleep, coughing, etc), and altitude
●Apnea
●Acute respiratory failure
We consider nonsevere bronchiolitis to be indicated by the absence of all of the above. However, the severity categories may overlap and clinical judgment is necessary to make appropriate management decisions.
Repeated observations are necessary to adequately assess disease severity because examination findings may vary substantially over time [1].
INDICATIONS FOR HOSPITALIZATION — Although clinical practice varies widely [2-4], hospitalization for supportive care and monitoring usually is indicated for infants and young children with [5-7]:
●Toxic appearance, poor feeding, lethargy, or dehydration
●Moderate to severe respiratory distress, manifested by one or more of the following signs: nasal flaring; intercostal, subcostal, or suprasternal retractions; respiratory rate >70 breaths per minute; dyspnea; or cyanosis
●Apnea
●Hypoxemia with or without hypercapnia (arterial or capillary carbon dioxide tension >45 mmHg); studies evaluating SpO2 (oxygen saturation) <95 percent as a predictor of disease severity or progression among outpatient children with bronchiolitis have inconsistent results [8,9]; nonetheless, the authors of this topic use SpO2 <95 percent on room air at sea level as a finding that may warrant admission (see 'Supplemental oxygen' below)
●Caregivers who are unable to care for them at home
Although age <12 weeks is a risk factor for severe or complicated disease, young age in and of itself is not an indication for hospitalization. (See "Bronchiolitis in infants and children: Clinical features and diagnosis", section on 'Risk factors for severe disease'.)
Hypoxemia is often used as a criterion for admission in infants without comorbid conditions for severe disease. However, it should not be the only criterion. Observational studies suggest that episodes of desaturation with mild to moderate respiratory distress are common in infants with bronchiolitis and that continuous monitoring for hypoxemia may be associated with increased health care utilization (eg, supplemental oxygen, admission, increased length of stay) but little or no acute benefit [4,10-13]. The effect of brief periods of hypoxemia caused by bronchiolitis on the developing brain has not been adequately addressed.
In an observational study (2008 to 2013), the caregivers of 118 otherwise healthy infants (6 weeks to 12 months) who were born at >36 weeks' gestation and discharged home from the emergency department with a diagnosis of acute bronchiolitis were provided with a portable oxygen saturation monitor that recorded SpO2 but neither displayed saturation values nor sounded alarms for threshold values [12]. Based on clinical characteristics at discharge from the emergency department, these infants had mild to moderate bronchiolitis that did not require hospitalization. Approximately two-thirds of infants had at least one episode of SpO2 <90 percent for at least one minute; one-half had at least three episodes; and 43 percent had SpO2 <90 percent continuously for ≥3 minutes. Episodes of desaturation typically occurred during sleep or while feeding. The rates of unscheduled medical visits and hospitalizations for bronchiolitis within 72 hours of discharge from the emergency department were similar among infants with and without desaturations (approximately 25 percent and <5 percent, respectively). Information beyond 72 hours post-discharge was not collected, which is a limitation of the study.
NONSEVERE BRONCHIOLITIS
Overview of approach — Infants and children with nonsevere bronchiolitis usually can be managed in the outpatient setting, unless there are concerns about the caregivers' ability to care for them at home. (See 'Indications for hospitalization' above.)
Supportive care and anticipatory guidance are the mainstays of management of nonsevere bronchiolitis. Supportive care includes maintenance of adequate hydration, relief of nasal congestion/obstruction, and monitoring for disease progression. (See 'Anticipatory guidance' below and 'Follow-up' below.)
For immune-competent infants and children with nonsevere bronchiolitis who are treated in the office or emergency department, we do not routinely recommend pharmacologic interventions because they lack proven benefit, increase the cost of care, and may have adverse effects. Randomized trials, systematic reviews, and meta-analyses do not support the benefits of bronchodilators (inhaled or oral) [14-19], glucocorticoids (inhaled or systemic) [1,20-24], or leukotriene inhibitors [25]. Antibiotics are indicated only if there is evidence of a coexisting bacterial infection. This approach is consistent with that of the American Academy of Pediatrics, the National Institute for Care Excellence, and other professional organizations [1,5,7,26,27]. (See 'Interventions that are not routinely recommended' below and 'Society guideline links' below.)
For infants and children with nonsevere bronchiolitis who are treated in the office or emergency department, we suggest not routinely treating with nebulized hypertonic saline. In a 2015 systematic review of randomized trials evaluating administration of hypertonic saline in the emergency department, hypertonic saline reduced the rate of hospitalization among children with bronchiolitis, but the evidence was of low quality [26].
Anticipatory guidance — Education and anticipatory guidance are important aspects of the management of bronchiolitis [5,26]. Components of education and anticipatory guidance include:
●Expected clinical course: Typical illness with bronchiolitis begins with upper respiratory tract symptoms. Lower respiratory symptoms and signs develop on days 2 to 3, peak on days 3 to 5, and then gradually resolve over the course of two to three weeks.
In a systematic review of four studies including 590 children with bronchiolitis who were seen in outpatient settings and not treated with bronchodilators [17,28-30], the mean time to resolution of cough ranged from 8 to 15 days [31]. Cough resolved in 50 percent of patients within 13 days and in 90 percent within 21 days. In a cohort of 181 children (not included in the systematic review), the median duration of caretaker-reported symptoms was 12 days; approximately 20 percent continued to have symptoms for at least three weeks, and 10 percent had symptoms for at least four weeks [32].
●Proper techniques for suctioning the nose (table 1). (See "Patient education: Bronchiolitis and RSV in infants and children (Beyond the Basics)", section on 'Nose drops or spray'.)
●The need to monitor fluid intake and output; children with bronchiolitis may have difficulty maintaining adequate hydration because of increased needs (related to fever and tachypnea) and decreased intake (related to tachypnea and respiratory distress).
●Avoidance of over-the-counter decongestants and cough medicines; these medications have no proven benefit and may have serious adverse effects [33]. (See "The common cold in children: Management and prevention", section on 'Over-the-counter medications'.)
●Indications to return to medical care immediately: apnea, cyanosis, poor feeding, new fever, increased respiratory rate and/or increased work of breathing (retractions, nasal flaring, grunting), decreasing fluid intake (<75 percent of normal, no wet diaper for 12 hours), exhaustion (eg, failure to respond to social cues, waking only with prolonged stimulation) [5,26].
●Strategies to prevent respiratory infection. (See 'Prevention' below.)
Follow-up — Children with bronchiolitis who are not hospitalized should be monitored by their clinician for progression and resolution of disease. Follow-up, usually within one to two days, may occur by phone or at the office. The timing and method of follow-up depend upon initial severity and duration of symptoms; patients who are seen in the first one to two day of symptoms may worsen before they improve. Repeated clinical assessments of the respiratory system (eg, respiratory rate, nasal flaring, retractions, grunting) may be necessary to determine the course of the illness and to identify deteriorating respiratory status. (See 'Anticipatory guidance' above.)
In children who do not improve as expected, chest radiographs may be helpful in excluding other conditions in the differential diagnosis (eg, foreign body aspiration, heart failure, vascular ring) [1]. Those whose cough persists for ≥4 weeks should be evaluated for chronic cough. (See "Bronchiolitis in infants and children: Clinical features and diagnosis", section on 'Differential diagnosis' and 'Anticipatory guidance' above.)
SEVERE BRONCHIOLITIS — Infants and children with severe bronchiolitis require assessment in the emergency department and usually require supportive care in the inpatient setting. Supportive care and anticipatory guidance are the mainstays of management of severe bronchiolitis. Supportive care includes maintenance of adequate hydration, respiratory support, and monitoring for disease progression. (See 'Severity assessment' above and 'Indications for hospitalization' above.)
Emergency department management — Emergency department management of severe bronchiolitis centers on stabilization of respiratory and fluid status and determining the appropriate setting for continuation of care (ie, observation unit, general inpatient ward, or intensive care unit [ICU]). In a network meta-analysis, no intervention (eg, nebulized bronchodilators, nebulized or systemic glucocorticoids, nebulized hypertonic saline) reduced the rate of hospital admission by day 7 [34].
●Trial of inhaled bronchodilator – We do not routinely suggest inhaled bronchodilators for the management of the first episode of bronchiolitis in children.
However, a one-time trial of inhaled bronchodilators (albuterol [salbutamol] or epinephrine) may be warranted for infants and children with severe bronchiolitis. Children with severe disease or respiratory failure generally were excluded from trials evaluating inhaled bronchodilators in children with bronchiolitis. (See 'Severity assessment' above and 'Bronchodilators' below.)
●Nebulized hypertonic saline – For infants and children with severe bronchiolitis who are treated in the emergency department, we suggest not routinely treating with nebulized hypertonic saline. (See 'Nebulized hypertonic saline' below.)
●Glucocorticoids – We recommend not using glucocorticoids routinely in the management of the first episode of bronchiolitis. (See 'Glucocorticoids' below.)
Inpatient management — Inpatient management of severe bronchiolitis centers on support of hydration and respiratory status as necessary. High-quality evidence of benefit of other interventions (ie, nebulized bronchodilators, nebulized or systemic glucocorticoids, nebulized hypertonic saline) is lacking [34]. In addition to standard precautions, children admitted with bronchiolitis should be placed on contact precautions. (See "Infection prevention: Precautions for preventing transmission of infection", section on 'Standard precautions' and "Infection prevention: Precautions for preventing transmission of infection", section on 'Contact precautions'.)
Fluid management — The fluid intake and output of infants and children with bronchiolitis should be assessed regularly. Children with bronchiolitis may have difficulty maintaining adequate hydration because of increased needs (related to fever and tachypnea) and decreased intake (related to tachypnea and respiratory distress).
Exclusive parenteral fluid administration may be necessary to ensure adequate hydration and avoid the risk of aspiration in infants and children who are hospitalized with bronchiolitis and have moderate to severe respiratory distress (nasal flaring; intercostal, subcostal, or suprasternal retractions; respiratory rate >70 breaths per minute; dyspnea; or cyanosis) [1,35]. For children who can tolerate enteral feedings, strategies to maintain hydration include small frequent feedings or orogastric or nasogastric feedings [5,36-39]. (See "Maintenance intravenous fluid therapy in children" and "Overview of enteral nutrition in infants and children", section on 'Indications for enteral nutrition'.)
It is also important to monitor urine output. Plasma antidiuretic hormone levels rarely may be elevated, leading to fluid retention and hyponatremia [40-42]. Fluid overload should be avoided, since it may lead to pulmonary congestion and worse outcomes [43]. (See "Pathophysiology and etiology of the syndrome of inappropriate antidiuretic hormone secretion (SIADH)", section on 'Pulmonary disease' and "Maintenance intravenous fluid therapy in children".)
Respiratory support — Respiratory support for infants and young children with bronchiolitis generally is provided in a stepwise fashion. Most children require nasal suctioning. Supplemental oxygen is provided as necessary to maintain SpO2 >90 to 92 percent. Infants who are at risk for progression to respiratory failure often receive a trial of heated humidified high-flow nasal cannula (HFNC) therapy and/or continuous positive airway pressure (CPAP) before endotracheal intubation. However, initial endotracheal intubation is more appropriate than HFNC or CPAP for children with hemodynamic instability, intractable apnea, or loss of protective airway reflexes.
Nasal suctioning — For children hospitalized with bronchiolitis, we suggest mechanical aspiration of the nares as necessary to relieve nasal obstruction. Saline nose drops and mechanical aspiration of nares may help to relieve partial upper airway obstruction in infants and young children with respiratory distress or feeding difficulties. In a retrospective cohort study of 740 infants (2 to 12 months) hospitalized with bronchiolitis, those who had three or four lapses of mechanical suctioning of more than four hours had longer hospital stay than those who had no lapses in suctioning (2.64 versus 1.62 days) [44].
There is little evidence to support routine frequent "deep" suctioning of the oropharynx or larynx with a nasopharyngeal catheter [1]. Catheter suctioning of the nasopharynx is traumatic and may produce edema and nasal obstruction. Catheter suctioning of the oropharynx can induce cough, but the theoretic complication of laryngospasm is not corroborated. In the retrospective cohort study of 740 patients hospitalized with bronchiolitis, those who had >60 percent deep suctioning (ie, via negative pressure vacuum system and nasopharyngeal catheter) during the first 24 hours of admission had longer hospital stay than patients with ≤60 percent deep suctioning (2.35 versus 1.75 days) [44]. Prospective randomized studies are needed to confirm this observation, which may be confounded by more frequent suctioning of infants perceived to be sicker.
Supplemental oxygen — Supplemental oxygen should be provided by nasal cannula, face mask, or head box to maintain SpO2 above 90 to 92 percent [45].
Data are lacking to support the use of a specific SpO2 cutoff value. The American Academy of Pediatrics practice guideline suggests SpO2 <90 percent as the threshold to start supplemental oxygen [1]. However, variability in the accuracy of oximeters, and concomitant fever, acidosis, or hemoglobinopathy favor the use of a higher cutoff value. In a multicenter study comparing oxygen saturation simultaneously measured with pulse oximetry (SpO2) and arterial blood gas (SaO2), the accuracy of pulse oximetry varied with the range of oxygen saturation [46]. In the SpO2 range of 76 to 90 percent, pulse oximetry tended to overestimate SaO2 (by a median of approximately 5 percent); in the SpO2 range of 91 to 97 percent, SpO2 and SaO2 values were similar (median difference of 1 percent).
Close monitoring is required as supplemental oxygen is weaned, particularly for children with hemodynamically significant heart disease, bronchopulmonary dysplasia, and premature birth. (See "Continuous oxygen delivery systems for the acute care of infants, children, and adults".)
HFNC and CPAP — Although standard oxygen therapy is effective for the majority of children with bronchiolitis who require supplemental oxygen [47,48], heated humidified high-flow nasal cannula (HFNC, also called high-flow warm humidified oxygen) therapy and/or continuous positive airway pressure (CPAP) are used to reduce the work of breathing, improve gas exchange, and avoid endotracheal intubation in children with bronchiolitis who are at risk for progression to respiratory failure [49-54]. Successful therapy with HFNC or CPAP avoids the adverse effects of endotracheal intubation (eg, laryngeal injury, ventilator-induced lung injury, ventilator-associated pneumonia, narcotic dependence and withdrawal) [55].
HFNC and CPAP typically require care in an intensive or intermediate care unit. However, some institutions initiate HFNC in the emergency department or on the general ward, which appears to be safe [51,56-58]. A detailed discussion of critical care respiratory interventions for infants and young children with bronchiolitis is beyond the scope of this review. General discussions of invasive and noninvasive ventilation strategies for infants and children with respiratory failure are provided separately. (See "Initiating mechanical ventilation in children" and "High-flow nasal cannula oxygen therapy in children" and "Noninvasive ventilation for acute and impending respiratory failure in children".)
●HFNC therapy – Our institutions use HFNC therapy to avoid endotracheal intubation in infants and children with bronchiolitis who have failed standard oxygen therapy and are at risk for respiratory failure (eg, persistently increased respiratory effort, hypoxemia). In observational studies, HFNC has been associated with decreased rates of endotracheal intubation [51,59-63]. Although this benefit has not been proven in randomized trials, HFNC may avoid the need for endotracheal intubation and is better tolerated and has fewer adverse effects than CPAP [52,54,64]. Among children admitted to the ICU, compared with CPAP, HFNC may reduce the use of sedation, duration of ICU stay, and duration of hospitalization [54].
Our institutions do not routinely provide HFNC to children with nonsevere bronchiolitis. Although early initiation of HFNC may reduce the need for escalation of care [56,65], it has not been shown to decrease the length of hospitalization, duration of oxygen therapy, or rate of intubation in children with nonsevere bronchiolitis [53,64,66-68].
HFNC is a well-tolerated noninvasive method of ventilatory support that permits high inspired gas flows (4 to 8 L/min) with or without increased oxygen concentration [69,70]. The increased flows are tolerated because the air is humidified; provision of HFNC requires a special circuit – it cannot be provided by simply turning up the flow from the wall unit. Flow rates ≥6 L/min can generate positive expiratory pressures in the range of 2 to 5 cm H2O. The size of the nasal cannula, which is determined by fit, affects the size of the circuit and maximum amount of flow. For the treatment of bronchiolitis in infants and children younger than two years, 8 L/min is generally the maximum flow rate, but higher rates may be used (cannula size permitting) [71,72].
Contraindications to HFNC include abnormalities of the face or airway that preclude an appropriate-fitting nasal cannula [73]. Relative contraindications include confusion or agitation, vomiting, excessive secretions, and bowel obstruction. In an observational study, nonresponse to HFNC was associated with lower pretherapy pH and higher pretherapy PCO2, highlighting the importance of early initiation [74].
Complications of HFNC include abdominal distension, aspiration, barotrauma, and pneumothorax (rare) [73]. However, the risk of pneumothorax is lower with HFNC than with mechanical ventilation following endotracheal intubation. In a meta-analysis of three randomized trials, no difference in the rate of adverse events was detected between HFNC and standard oxygen therapy (0.7 percent) [64]; in a meta-analysis of two trials comparing HFNC and CPAP, the risk of adverse events was lower with HFNC than CPAP (8 versus 20 percent; risk ratio [RR] 0.36, 95% CI 0.17-0.74).
Infants receiving HFNC who are clinically deteriorating may develop significant respiratory acidosis (hypercapnia) despite high oxygen saturations (if they are receiving supplemental O2). Oxygen saturation is a poor indicator of impending respiratory failure, which is better indicated by marked retractions, decreased or absent breath sounds, fatigue, and poor responsiveness to stimulation (eg, weak or no cry). Blood gas analysis to assess ventilation (ie, PCO2 levels) may be warranted in infants receiving HFNC who become more dyspneic and/or tachycardic.
A systematic review of nine unmasked randomized trials including 2121 children with bronchiolitis concluded that HFNC does not substantially benefit children with bronchiolitis compared with standard oxygen therapy or CPAP, although it appears to be safe and may decrease treatment failure (discontinuation of current therapy or escalation of care due to deterioration or adverse events) compared with standard oxygen therapy [64]. Meta-analysis of four trials (1640 participants) did not detect a difference in length of stay between HFNC and standard oxygen therapy (mean difference -1.5 days, 95% CI -3.3 to 0.3 days). Additional meta-analyses did not detect differences in length of oxygen supplementation (mean difference 0.6 days, 95% CI -1.7 to 0.5 days) or transfer to the ICU (RR 1.30, 95% CI 0.98-1.72). Although meta-analyses of two trials comparing HFNC with standard oxygen therapy did not detect differences in the rates of intubation, only 12 of 1526 participants required intubation. In meta-analysis of two trials conducted in emergency departments (1674 participants) [56,65], HFNC reduced treatment failure (discontinuation of current therapy or escalation of care due to deterioration or adverse events) compared with standard oxygen therapy (RR 0.50, 95% CI 0.40-0.62) [64].
Additional trials are being conducted to determine the effectiveness and effect of various flow rates on airway pressure, breathing patterns, and respiratory effort in infants hospitalized with bronchiolitis [75-78]. Flow rates of ≥6 L/min appear to provide positive pressure throughout the respiratory cycle, with positive end expiratory pressures in the range of 2 to 5 cm H2O [73,76,79]. A multicenter trial is needed to determine the optimal flow rate required for clinical benefit.
●CPAP – Our institutions use continuous positive airway pressure (CPAP) to avoid endotracheal intubation in infants and children with bronchiolitis who have failed standard oxygen therapy and are at risk for respiratory failure (eg, persistently increased respiratory effort, hypoxemia) but less frequently than we use HFNC. Although CPAP can decrease work of breathing and prevent endotracheal intubation in children with progressive hypoxemia or hypercarbia [80], it is associated with greater adverse effects (eg, nasal trauma) [54]. In children who fail HFNC, CPAP may be tried before endotracheal intubation. (See "Noninvasive ventilation for acute and impending respiratory failure in children".)
Several observational and randomized studies suggest that CPAP improves ventilation and oxygenation in infants with bronchiolitis and severe respiratory distress, may avoid endotracheal intubation, and may be associated with decreased length of stay in the ICU [52,55,81-90]. However, a systematic review found the evidence regarding CPAP for bronchiolitis to be inconclusive because of methodologic limitations and imprecision in the existing studies [91]. Additional studies are necessary to clarify the benefits of CPAP for infants with bronchiolitis who are admitted to an ICU.
Endotracheal intubation — Infants who have ongoing or worsening severe distress despite a trial of HFNC and/or CPAP, those who have hypoxemia despite oxygen supplementation, and those with apnea may require endotracheal intubation and mechanical ventilation. Signs of impending respiratory failure in infants and young children with bronchiolitis include marked retractions, decreased or absent breath sounds, fatigue, and poor responsiveness to stimulation (eg, weak or no cry). Arterial or venous blood gases obtained in infants with impending respiratory failure often reveal hypercapnia (ie, carbon dioxide tension >55 mmHg [arterial sample] or >60 mmHg [venous sample]); however, blood gases should not be used as the sole basis for deciding to intubate. Endotracheal intubation is discussed separately. (See "Emergency endotracheal intubation in children".)
Other therapies — We do not routinely suggest chest physiotherapy, inhaled bronchodilators, nebulized hypertonic saline, or leukotriene inhibitors (eg, montelukast) to relieve lower airway obstruction in infants and children with a first episode of bronchiolitis. We do not recommend glucocorticoids in the management of a first episode of bronchiolitis. (See 'Interventions that are not routinely recommended' below.)
Although we do not routinely suggest inhaled bronchodilators for the management of bronchiolitis, a one-time trial of inhaled bronchodilators (albuterol [salbutamol] or epinephrine) may be warranted for infants and children with bronchiolitis and severe disease. Children with severe disease or respiratory failure generally were excluded from trials evaluating inhaled bronchodilators in children with bronchiolitis. (See 'Severity assessment' above and 'Bronchodilators' below.)
Chest physiotherapy may be warranted in children with comorbidities associated with difficulty clearing respiratory secretions (eg, neuromuscular disorders, cystic fibrosis) [26]. However, in previously healthy children with bronchiolitis, chest physiotherapy has not been shown to be useful [92]. (See 'Chest physiotherapy' below.)
There is little evidence to support the benefit of adjunctive glucocorticoids or surfactant in the management of respiratory failure due to bronchiolitis. A meta-analysis of three studies evaluating the use of systemic glucocorticoids in infants with bronchiolitis requiring admission to the ICU did not find an effect on duration of mechanical ventilation or length of hospitalization [93]. Another meta-analysis of several small randomized trials evaluating surfactant therapy in mechanically ventilated infants with bronchiolitis concluded that surfactant therapy may shorten the duration of mechanical ventilation and duration of ICU stay in children with bronchiolitis [94-97]. However, additional studies are needed before reliable estimates of the magnitude of the effects can be made.
Monitoring clinical status
●Respiratory status – Repeated clinical assessment of the respiratory system (eg, respiratory rate, nasal flaring, retractions, grunting) is necessary to identify deteriorating respiratory status [98].
Early in the admission, hospitalized infants should have monitoring of heart rate, respiratory rate, and SpO2. In settings with respiratory monitoring capabilities (eg, ICU), respiratory rate should be monitored continuously; in other settings (eg, general ward), respiratory rate should be monitored with vital signs. Infants with severe distress or who have apnea should be monitored in the ICU. An arterial or capillary blood gas sample to assess PCO2 levels may be indicated in children who require intensive care and should be repeated as clinically indicated. (See 'HFNC and CPAP' above.)
A change from continuous to intermittent measurement of SpO2 may be instituted as the clinical course improves and the patient no longer requires supplemental oxygen [99,100]. However, consensus regarding a safe and acceptable SpO2 threshold for hospital discharge is lacking [1,101-104].
In children who do not improve at the expected rate, chest radiographs may be helpful in excluding other conditions in the differential diagnosis (eg, foreign body aspiration, heart failure, vascular ring, tuberculosis, cystic fibrosis) [1]. (See "Bronchiolitis in infants and children: Clinical features and diagnosis", section on 'Differential diagnosis'.)
●Fluid status – The fluid intake and output of infants and children with bronchiolitis should be assessed regularly. It is also important to monitor urine output. Plasma antidiuretic hormone levels rarely may be elevated, leading to fluid retention and hyponatremia [40-42]. (See 'Fluid management' above.)
Clinical course — Although discharge criteria vary from center to center, in multicenter-studies of children younger than two years hospitalized with bronchiolitis, the median length of stay was two days [105,106]. Length of stay may be shorter in children with bronchiolitis due to rhinovirus and longer in children with respiratory syncytial virus-rhinovirus coinfection [105-107]. The respiratory status typically improves over two to five days [101,108-112]. However, wheezing persists in some infants for a week or longer. The course may be prolonged in younger infants and those with comorbid conditions (eg, bronchopulmonary dysplasia) [8,113].
In a multicenter, multiyear prospective study of 1916 children hospitalized with bronchiolitis, the time between symptom onset and clinical improvement ranged from 1 to 33 days (median four days) [114]. However, 96 percent of patients continued to improve once they met certain clinical improvement criteria, including no retractions or mild retractions; decreasing or stable respiratory rate of <60 breaths/minute for age <6 months, <55 breaths/minute for age 6 to 11 months, <45 breaths/minute for age ≥12 months; ambient air oxygen saturation ≥90 percent and not lower than 88 percent; and ability to maintain hydration orally. Risk factors for worsening after initial clinical improvement included age <2 months, <37 weeks gestational age, and severe retractions, apnea, or dehydration at presentation [1,5,14-16,20,115].
Discharge criteria — Minimal clinical criteria for discharge from the hospital or emergency department include [5,6,26]:
●Respiratory rate <60 breaths per minute for age <6 months, <55 breaths per minute for age 6 to 11 months, and <45 breaths per minute for age ≥12 months
●Caretaker knows how to clear the infant's airway using bulb suctioning
●Patient is stable while breathing ambient air; discharge from the hospital requires that the patient remain stable for at least 12 hours prior to discharge
●Patient has adequate oral intake to prevent dehydration
●Resources at home are adequate to support the use of any necessary home therapies (eg, bronchodilator therapy if the trial was successful and this therapy is to be continued)
●Caretakers are confident they can provide care at home
●Education of the caregivers is complete (see 'Anticipatory guidance' above)
In addition, we generally prefer that hospitalized children maintain oxygen saturation ≥90 percent while breathing ambient air because this is predictive of continued improvement [114]. However, some observational studies suggest that strict adherence to pulse oximetry criteria is associated with increased health care utilization [4,10,11].
Discharge counseling — We counsel caregivers of children who have been admitted with bronchiolitis to seek medical care if the child develops wheezing or breathing difficulty during subsequent upper respiratory infections because of their known increased risk for wheezing [116]. (See 'Outcome' below.)
We also recommend avoidance of smoke exposure and timely receipt of routine childhood immunizations, particularly influenza and pneumococcal vaccines.
OUTCOME — Bronchiolitis is a self-limited illness and often resolves without complications in most previously healthy infants. Severely affected infants, especially those born prematurely and those with underlying cardiopulmonary disease or immunodeficiency, are at increased risk for complications (eg, apnea, respiratory failure, secondary bacterial infection). Approximately 30 percent of previously healthy infants hospitalized for bronchiolitis are at an increased risk for recurrent wheezing [117]. (See "Bronchiolitis in infants and children: Clinical features and diagnosis", section on 'Complications'.)
The overall mortality rate in children hospitalized with respiratory syncytial virus (RSV) bronchiolitis in developed countries is less than 0.1 percent [118]. Mortality is increased in young infants (6 to 12 weeks), those with low birth weight, and those with underlying medical conditions (eg, underlying cardiopulmonary disease, immune deficiency) [101,119,120].
Infants hospitalized for lower respiratory tract infection (LRTI), especially RSV and rhinovirus, are at increased risk for recurrent wheezing and reduced pulmonary function, particularly during the first decade of life [121-128]. In a prospective cohort, LRTI with RSV increased the risk for subsequent frequent and infrequent wheezing (odds ratio 4.3 and 3.2, respectively) and was associated with reduced forced expiratory volume in children up to 11 years of age [129]. However, this association was lost by age 13 years, perhaps due to inadequate sample size. Similar findings have been observed for infants infected with rhinovirus [125,130].
Whether bronchiolitis in early childhood, especially that caused by RSV and rhinovirus, is associated with the development of asthma is uncertain. In some studies, a correlation exists between infection with RSV and the later development of asthma. However, this may reflect the multifactorial nature of risk for asthma, including a genetic predisposition to airway reactivity, exposure to environmental pollutants such as smoke, immunologic mechanisms, and disruption of the growth and development of the lungs due to viral infection in early childhood. (See "Role of viruses in wheezing and asthma: An overview" and "Risk factors for asthma", section on 'Respiratory infections' and "Respiratory syncytial virus infection: Clinical features and diagnosis", section on 'Pulmonary sequelae'.)
PREVENTION
●Primary and secondary prevention – Standard strategies to reduce the risk of bronchiolitis and accompanying morbidity include hand hygiene (washing with soap or with alcohol-based rubs) to minimize transmission of infectious agents, minimizing passive exposure to cigarette smoke, and avoiding contact with individuals with respiratory tract infections [1].
Immunoprophylaxis with palivizumab, a humanized monoclonal antibody against the respiratory syncytial virus (RSV) F glycoprotein, decreases the risk of hospitalization due to severe RSV illness among preterm infants and those with chronic lung disease and hemodynamically significant congenital heart disease. The American Academy of Pediatrics guidance for palivizumab immunoprophylaxis has become increasingly restricted, driven in part by the high cost associated with monthly administration. The indications and administration of palivizumab are discussed separately. (See "Respiratory syncytial virus infection: Prevention in infants and children", section on 'Palivizumab immunoprophylaxis'.)
Vaccines to prevent the most common causes of bronchiolitis (RSV, rhinovirus, human metapneumovirus, and parainfluenza virus) are unavailable. However, annual influenza immunization is recommended for everyone older than six months. Priority is given to children age 6 through 59 months and household contacts of children age 0 through 59 months because children younger than five years are at increased risk for influenza-related hospitalization and health care utilization. (See "Seasonal influenza in children: Prevention with vaccines", section on 'Target groups'.)
●Prevention of sequelae – We suggest not using inhaled glucocorticoids or azithromycin to attenuate airway inflammation for the prevention of subsequent wheezing episodes in infants and children with bronchiolitis. In randomized trials and meta-analysis, neither inhaled glucocorticoids (budesonide, fluticasone, dexamethasone) nor azithromycin have been beneficial in reducing subsequent wheezing episodes [21-24,131].
We do not suggest montelukast or other leukotriene inhibitors for the prevention of airway reactivity after bronchiolitis. Randomized trials of montelukast for the prevention of airway reactivity have had inconsistent results [132-134]; heterogeneity in severity of disease, duration of treatment, and outcome measures precluded pooled analysis [25]. However, in the largest trial (n = 979), montelukast was not associated with improvement in post-RSV bronchiolitis respiratory symptoms [133].
INTERVENTIONS THAT ARE NOT ROUTINELY RECOMMENDED
Bronchodilators
●Inhaled bronchodilators – We do not suggest routine administration of inhaled bronchodilators for children with bronchiolitis. Meta-analyses of randomized trials and systematic reviews suggest that bronchodilators may provide modest short-term clinical improvement but do not affect overall outcome, may have adverse effects, and increase the cost of care [14-16,115,135].
Although we do not suggest routine administration of inhaled bronchodilators for children with first episode of bronchiolitis, a one-time trial of inhaled bronchodilators (albuterol [salbutamol] or epinephrine) may be warranted for infants and children with bronchiolitis and severe disease (ie, persistently increased respiratory effort [tachypnea, nasal flaring, retractions, accessory muscle use, grunting], hypoxemia, apnea, or respiratory failure).
Children with severe disease or respiratory failure generally were excluded from trials evaluating inhaled bronchodilators in children with bronchiolitis. In addition, a subset of young children with the clinical syndrome of bronchiolitis may have virus-induced wheezing or asthma and may benefit from inhaled bronchodilator therapy. In a prospective multicenter study of children hospitalized with bronchiolitis, children with rhinovirus-associated bronchiolitis were more likely than those with respiratory syncytial virus (RSV)-associated bronchiolitis to be >12 months of age and to have a history of wheezing and eczema [136], groups that also may have been excluded from trials evaluating bronchodilators. (See 'Emergency department management' above and 'Other therapies' above and "Treatment of recurrent virus-induced wheezing in young children", section on 'Episodic therapy'.)
For patients in whom such a trial is warranted, we suggest albuterol 0.15 mg/kg (minimum 2.5 mg; maximum 5 mg) diluted in 2.5 to 3 mL normal (0.9 percent) saline and administered over 5 to 15 minutes or four to six puffs via a metered dose inhaler with spacer and face mask. We prefer albuterol to epinephrine because albuterol is more appropriate for administration in the home setting. The effects should be monitored by evaluating the child before and up to one hour after treatment, recognizing that the clinician's ability to assess response may be limited [137]. If there is a clinical response to albuterol, it can be administered as needed (based on clinical status) every four to six hours and discontinued when the signs and symptoms of respiratory distress improve [15].
Multiple professional groups recommend that bronchodilators not be used routinely in the management of bronchiolitis [1,5,20,26,27]. (See 'Society guideline links' below.)
●Oral bronchodilators – We recommend against the use of oral bronchodilators in the management of bronchiolitis. In randomized trials, oral bronchodilators have neither shortened clinical illness nor improved clinical parameters, but were associated with adverse effects (eg, increased heart rate) [17-19].
Glucocorticoids
●Systemic glucocorticoids – For healthy infants and young children with a first episode of bronchiolitis, we recommend not using systemic glucocorticoids [1,20,24].
Although the anti-inflammatory effects of glucocorticoids theoretically reduce airway obstruction by decreasing bronchiolar swelling, most studies show little effect in bronchiolitis. In a 2013 meta-analysis evaluating the use of systemic glucocorticoids (oral, intramuscular, or intravenous) for acute bronchiolitis in children (0 to 24 months of age), no significant differences were found in hospital admission rate, length of stay, clinical score after 12 hours, or hospital readmission rate [24].
Whether glucocorticoids provide benefit in subgroups of children with bronchiolitis is uncertain. Some patients presenting with the first episode of bronchiolitis may be experiencing inflammation from asthma, and these patients can benefit from systemic glucocorticoids. Although patients with asthma can benefit from glucocorticoids, randomized controlled trials have demonstrated no benefit of oral glucocorticoids in young children with virus-associated wheezing [28,138]. In an observational study of 2479 children <2 years who had been hospitalized for bronchiolitis and had a subsequent hospitalization for asthma, administration of glucocorticoids during their hospitalization for bronchiolitis was not associated with improved outcomes [139]. (See "Acute asthma exacerbations in children younger than 12 years: Emergency department management" and "Acute asthma exacerbations in children younger than 12 years: Inpatient management".)
●Inhaled glucocorticoids – We do not suggest inhaled glucocorticoids for the treatment of bronchiolitis. In randomized trials and meta-analysis, inhaled glucocorticoids (budesonide, fluticasone, dexamethasone) have not been beneficial in reducing symptom duration or readmission rates [21-24].
●Bronchodilators plus glucocorticoids – We do not suggest combination therapy with bronchodilators plus glucocorticoids for infants and children with a first episode of bronchiolitis. Although a randomized trial suggested that administration of nebulized epinephrine and oral dexamethasone in the emergency department decreased the rate of hospitalization within one week of the emergency department visit, the result was not significant when adjusted for multiple comparisons [28]. Additional support of benefit and additional information about the long-term effects of combination bronchodilator/glucocorticoid therapy is necessary before combination therapy can be considered for infants with a first episode of virus-induced wheezing [28,140].
Nebulized hypertonic saline
●In the emergency department – For infants and children with severe bronchiolitis who are treated in the emergency department, we suggest not routinely treating with nebulized hypertonic saline (of any concentration). In a 2018 meta-analysis of eight randomized trials evaluating administration of hypertonic saline in the emergency department, hypertonic saline reduced the rate of hospitalization among children with bronchiolitis (risk ratio 0.77, 95% CI 0.62-0.96), but there was substantial heterogeneity [141].
●For hospitalized children – For infants and children admitted to the hospital with bronchiolitis, we suggest not routinely treating with nebulized hypertonic saline. In a meta-analysis of 20 randomized trials (2350 participants) in children hospitalized with bronchiolitis, length of stay was similar in the hypertonic saline and normal saline groups (mean difference -0.3 days, 95% CI -0.66 to 0.05) [141,142]. A network meta-analysis of randomized trials concluded that nebulized hypertonic saline (with or without epinephrine) may reduce length of stay, but the evidence is limited by imprecision, risk of bias, and heterogeneity [34].
Unless additional high quality studies show otherwise, nebulized hypertonic saline cannot be routinely recommended for hospitalized children with bronchiolitis [34].
The 2015 NICE bronchiolitis guideline recommends against the use of hypertonic saline in children with bronchiolitis [26]. The 2014 AAP clinical practice guideline on the management of bronchiolitis indicated that clinicians "may administer hypertonic saline to infants and children hospitalized for bronchiolitis" [1].
Chest physiotherapy — We suggest that chest physiotherapy not be used routinely in the management of bronchiolitis. A systematic review of 12 randomized trials concluded that chest physiotherapy did not reduce severity of disease or time to recovery [143]. The use of chest physiotherapy is discouraged because it may increase the distress and irritability of ill infants.
Chest physiotherapy may be warranted in children with comorbidities associated with difficulty clearing respiratory secretions (eg, neuromuscular disorders, cystic fibrosis) [26].
Antimicrobial agents and immunotherapies
●Antibiotics – Antibiotics should not be used routinely in the treatment of bronchiolitis, which is almost always caused by viruses [144-146]. Bronchiolitis does not increase the risk for serious bacterial infection. However, occasionally concomitant or secondary bacterial infections may occur. Coexisting bacterial infections should be treated in the same manner as they would be treated in the absence of bronchiolitis. (See "Bronchiolitis in infants and children: Clinical features and diagnosis", section on 'Microbiology' and "The febrile infant (29 to 90 days of age): Outpatient evaluation", section on 'Bronchiolitis' and "The febrile neonate (28 days of age or younger): Outpatient evaluation and initial management", section on 'Other viral infections'.)
●Ribavirin – We do not recommend ribavirin in the routine treatment of infants and children with bronchiolitis. However, in immunocompromised patients with severe bronchiolitis due to RSV, antiviral therapy may play a role. (See "Respiratory syncytial virus infection: Treatment", section on 'Ribavirin'.)
●Anti-RSV preparations – We do not recommend anti-RSV preparations for the treatment of bronchiolitis in infants and children. In randomized trials, intravenous immune globulin with a high neutralizing activity against RSV (RSV-IGIV, which has been discontinued) and RSV-specific humanized monoclonal antibody (palivizumab) failed to improve outcomes in infants (with or without risk factors) hospitalized with RSV infection [147-150]. (See "Respiratory syncytial virus infection: Prevention in infants and children", section on 'Palivizumab immunoprophylaxis'.)
Heliox — We do not suggest the routine use of heliox (a 70/30 or 80/20 mixture of helium and oxygen, respectively) in the treatment of bronchiolitis in infants and children. The administration of heliox is cumbersome and results in a relatively small benefit in a limited group of infants. A systematic review of six heterogeneous randomized trials of heliox for the treatment of bronchiolitis including 560 children concluded that heliox did not reduce the need for CPAP or intubation or the length of hospitalization [151]. (See "Physiology and clinical use of heliox", section on 'Technical issues'.)
Leukotriene inhibitors — We do not suggest montelukast or other leukotriene inhibitors for the treatment of bronchiolitis. Although leukotrienes appear to play a role in airway inflammation in bronchiolitis [152-155], a 2015 meta-analysis of five randomized trials did not find an effect on duration of hospitalization or clinical scores in children with bronchiolitis [25]. Additional studies are necessary to determine what role, if any, leukotriene inhibitors play in the management of acute bronchiolitis [156,157].
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Bronchiolitis in infants and children".)
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or email these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient education" and the keyword[s] of interest.)
●Basics topic (see "Patient education: Bronchiolitis and RSV in children (The Basics)")
●Beyond the Basics topic (see "Patient education: Bronchiolitis and RSV in infants and children (Beyond the Basics)")
SUMMARY AND RECOMMENDATIONS
●Definition – Bronchiolitis is broadly defined as a clinical syndrome of respiratory distress that occurs in children <2 years of age and is characterized by upper respiratory symptoms leading to lower respiratory infection with inflammation, which results in wheezing and or crackles. It typically occurs with primary infection or reinfection with a viral pathogen. (See 'Definition' above and "Bronchiolitis in infants and children: Clinical features and diagnosis", section on 'Diagnosis'.)
●Indications for hospitalization – Infants and children with moderate to severe respiratory distress (eg, nasal flaring, retractions, grunting, respiratory rate >70 breaths per minute, dyspnea, cyanosis) usually require hospitalization for supportive care and monitoring. Additional indications for hospitalization include toxic appearance, poor feeding, lethargy, apnea, and/or hypoxemia. (See 'Indications for hospitalization' above.)
●Management of nonsevere bronchiolitis – Infants and children with nonsevere bronchiolitis usually can be managed in the outpatient setting unless there are concerns about the caregivers' ability to care for them at home.
Supportive care (maintenance of adequate hydration, relief of nasal congestion/obstruction, monitoring disease progression) and anticipatory guidance are the mainstays of management. We generally do not use pharmacologic interventions (eg, bronchodilators, glucocorticoids) or nebulized hypertonic saline in the management of children with nonsevere bronchiolitis. (See 'Severity assessment' above and 'Nonsevere bronchiolitis' above.)
●Management of severe bronchiolitis – Infants and children with severe bronchiolitis require assessment in the emergency department and usually require supportive care in the inpatient setting.
Supportive care (maintenance of adequate hydration, provision of oxygen and respiratory support as necessary, monitoring disease progression) and anticipatory guidance are the mainstays of management of severe bronchiolitis. (See 'Severity assessment' above and 'Severe bronchiolitis' above and 'Fluid management' above and 'Supplemental oxygen' above and 'Monitoring clinical status' above.)
•We suggest not routinely administering inhaled bronchodilators (albuterol or epinephrine) to infants and children with a first episode of bronchiolitis (Grade 2B). (See 'Bronchodilators' above.)
However, a one-time trial of inhaled bronchodilators may be warranted for infants and children with bronchiolitis and severe disease. The bronchodilator response should be objectively assessed before and up to one hour after treatment. If there is a clinical response, aerosolized bronchodilator therapy can be administered every four to six hours as needed (based on clinical status) and discontinued when the signs and symptoms of respiratory distress improve. (See 'Severity assessment' above and 'Severe bronchiolitis' above and 'Bronchodilators' above.)
•We recommend not using systemic glucocorticoids routinely in the treatment of previously healthy infants hospitalized with a first episode of bronchiolitis (Grade 1A). We also suggest not using combination therapy with bronchodilators and glucocorticoids for infants and children with bronchiolitis (Grade 2B). (See 'Glucocorticoids' above.)
•We suggest not using nebulized hypertonic saline or heliox routinely in the treatment of bronchiolitis in infants and children (Grade 2B). (See 'Nebulized hypertonic saline' above and 'Heliox' above.)
•Infants and children with bronchiolitis and arterial or capillary carbon dioxide tension >55 mmHg, hypoxemia despite oxygen supplementation, and/or apnea may require mechanical ventilation. Noninvasive strategies that may be effective in reducing work of breathing, improving gas exchange, and avoiding the need for endotracheal intubation include heated humidified high-flow nasal cannula therapy and continuous positive pressure ventilation. (See 'HFNC and CPAP' above.)
●Discharge criteria – Minimal clinical criteria for discharge from the hospital, emergency department, or office include respiratory rate of <60 breaths per minute for age <6 months, <55 breaths per minute for age 6 to 11 months, and <45 breaths per minute for age ≥12 months; clinical stability without requiring supplemental oxygen; oral intake sufficient to prevent dehydration; and education of the caregiver. (See 'Discharge criteria' above and 'Anticipatory guidance' above.)
●Prevention – General strategies to prevent bronchiolitis include hand hygiene, minimizing passive exposure to cigarette smoke, avoiding contact with individuals with respiratory tract infections, and annual influenza immunization (for individuals older than six months). Immunoprophylaxis with palivizumab may decrease the risk of hospitalization in infants with bronchopulmonary dysplasia, premature infants, and hemodynamically significant congenital heart disease. (See 'Prevention' above and "Respiratory syncytial virus infection: Prevention in infants and children".)