Bronchiolitis in infants and children: Treatment, outcome, and prevention

INTRODUCTION — Bronchiolitis is a major cause of illness and hospitalization in infants and children younger than two years of age. The treatment, outcome, and prevention of bronchiolitis will be reviewed here.

Related topics include:

●(See "Bronchiolitis in infants and children: Clinical features and diagnosis".)

●(See "Respiratory syncytial virus infection: Clinical features and diagnosis in infants and children".)

●(See "Respiratory syncytial virus infection: Treatment in infants and children".)

●(See "Respiratory syncytial virus infection: Prevention in infants and children".)

●(See "Acute respiratory distress in children: Emergency evaluation and initial stabilization".)

●(See "Evaluation of wheezing in infants and children".)

●(See "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. It is characterized by initial upper respiratory symptoms (eg, rhinorrhea) followed by lower respiratory tract signs (eg, wheezing and/or crackles). Bronchiolitis is caused by viruses, most commonly respiratory syncytial virus (RSV). 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

Clinical assessment — We assess the following clinical parameters for determining the severity of bronchiolitis. Repeated observations are necessary to adequately assess disease severity because examination findings may vary substantially over time [1].

●Respiratory rate

●Respiratory effort (eg, retractions and accessory muscle use, grunting, nasal flaring)

●Oxygen saturation (SpO₂) – SpO₂ should be interpreted in the context of other clinical signs, the state of the patient (eg, awake, asleep, coughing, etc), and altitude

●Episodes of apnea lasting >15 seconds

●Mental status and responsiveness (ie, whether the infant appears to be tiring)

Infants with mild bronchiolitis have little to no respiratory distress and normal mental status and activity level.

Infants with moderately severe bronchiolitis are usually tachypneic with moderately increased work of breathing (ie, mild to moderate retractions without grunting or head bobbing), no apnea, and normal level of alertness.

Infants with severe bronchiolitis have persistent tachypnea and considerable respiratory distress (ie, retractions, grunting, nasal flaring, head bobbing). Other findings that indicate severe illness include apnea and/or poor responsiveness. Apnea occurs most commonly in preterm infants and those <2 months of age.

However, these severity categories may overlap and clinical judgment is necessary to make appropriate management decisions.

Severity scores — Numerous scoring instruments are available for assessing the severity of bronchiolitis, though few have been prospectively validated [2-4]. While these tools are widely used in research settings, their utility in routine clinical practice is uncertain. Nevertheless, they are commonly used in clinical practice to provide a uniform method for serially assessing illness severity.

Severity scores generally consist of a combination of vital signs and clinical findings. Variables that are commonly included are (table 1) [3]:

●Respiratory rate

●Degree of retractions/accessory muscle use

●Lung examination (aeration and degree of wheezing)

●Level of alertness, activity, and feeding

Commonly used tools include the respiratory severity score (RSS) (table 1) [5,6], Pediatric Emergency Research Network (PERN) tool [7], bronchiolitis risk of admission score (BRAS) [8], and Wood-Downes-Ferres score [9].

While these severity assessment tools have been adopted into routine clinical practice in many centers, it should be noted that they all have limitations. They are somewhat subjective (ie, the score may vary between different providers) and they sometimes do not capture the full clinical picture (eg, most scores do not account for apnea). Nevertheless, they can be a useful for following the child’s degree of respiratory compromise over time.

MILD BRONCHIOLITIS (OUTPATIENT MANAGEMENT)

Overview of approach — Infants and children with mild bronchiolitis (respiratory severity score [RSS] <5 (table 1)) 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' below.)

Supportive care and anticipatory guidance are the mainstays of management of mild 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.)

Infants and children with mild bronchiolitis who are treated in the office or emergency department generally do not require any specific pharmacologic interventions (eg, bronchodilators, glucocorticoids) since mildly affected patients generally recover well with supportive care alone.

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 [1,10-13]. (See 'Society guideline links' below.)

Anticipatory guidance — Education and anticipatory guidance are important aspects of the management of bronchiolitis [10,12]. 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. Thus, for infants who present early in the course of illness (first one to two days of symptoms), it is important to explain to the parents/caregivers that symptoms may worsen before they improve. (See 'Typical disease course' below.)

●Proper techniques for suctioning the nose (table 2). (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 can be harmful in young children [14]. (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) [10,12]. (See "Patient education: Bronchiolitis and RSV in infants and children (Beyond the Basics)", section on 'When to seek help'.)

●Strategies to prevent spread of the infection to others. (See 'Prevention' below.)

Follow-up — Infants and children with bronchiolitis who are managed in the outpatient setting should be monitored by their clinician for progression and resolution of disease. Follow-up within one to two days may occur by phone or in 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 patients who do not improve as expected, chest radiographs may be helpful in excluding other conditions in the differential diagnosis (eg, pneumonia, 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.)

EMERGENCY DEPARTMENT MANAGEMENT — Emergency department (ED) management of bronchiolitis focuses on stabilizing the infant's respiratory status, ensuring adequate hydration, and determining the appropriate setting of care (ie, outpatient management, observation unit, general inpatient ward, or pediatric intensive care unit).

Patients with mild symptoms (respiratory severity score [RSS] <5 (table 1)) usually can be managed in the outpatient setting unless there are concerns about the caregivers' ability to care for them at home. Supportive care and anticipatory guidance are the mainstays of management, as discussed above (see 'Mild bronchiolitis (outpatient management)' above). Criteria for discharge are summarized below. (See 'Discharge criteria' below.)

Patients with moderate to severe bronchiolitis (RSS ≥5 (table 1)) usually require supportive care and monitoring in the inpatient setting. (See 'Indications for hospitalization' below.)

Initial management in the ED includes:

●Initiation of respiratory support – Patients with persistent hypoxemia should receive supplemental oxygen as needed. Those with severe distress may require noninvasive ventilation (NIV) support (eg, with high-flow nasal canula or other NIV modality). (See 'Supplemental oxygen' below and 'Noninvasive ventilation' below.)

●Fluids – Patients with a history and/or clinical findings suggestive of dehydration should receive intravenous hydration, as appropriate. (See 'Fluid and nutrition management' below and "Treatment of hypovolemia (dehydration) in children in resource-abundant settings" and "Maintenance intravenous fluid therapy in children".)

●Nasal suctioning – Most patients with moderate to severe symptoms require intermittent nasal suctioning. (See 'Nasal suctioning' below.)

●Trial of inhaled bronchodilator – Bronchodilator therapy generally does not play a significant role in the management of bronchiolitis, particularly in patients without severe symptoms or wheezing. However, for patients with severe respiratory distress and wheezing, we suggest a trial of bronchodilator therapy. We typically use albuterol (salbutamol) for this purpose; other centers may use nebulized epinephrine. If the infant responds, additional treatments can be provided as needed. If the infant does not respond to bronchodilator therapy, it should not be continued. (See 'Severity assessment' above and 'Limited role of bronchodilator therapy' below.)

●Other interventions that are used selectively – The following interventions do not play a routine role in the ED management of bronchiolitis but may be used in select circumstances:

•We do not routinely treat with nebulized hypertonic saline at our center. However, other centers may use nebulized hypertonic saline in patients with ongoing moderate to severe symptoms despite nasal suctioning and NIV. (See 'Nebulized hypertonic saline' below.)

•Glucocorticoids are not routinely used in the management of the first episode of bronchiolitis. Use of glucocorticoids is generally limited to patients in whom there is clinical suspicion for underlying airway reactivity or asthma (eg, recurrent episodes of wheezing, especially if there is a personal or family history of asthma or atopic diseases). (See 'Limited role of glucocorticoids' below.)

•Antibiotics are indicated only in febrile neonates (age ≤28 days) or if there is evidence of a coexisting bacterial infection. (See 'Limited role of antibiotics' below and "The febrile neonate (28 days of age or younger): Outpatient evaluation and initial management".)

INDICATIONS FOR HOSPITALIZATION — Although clinical practice varies widely [15-17], hospitalization is generally indicated for infants and young children with any of the following [10,11,18]:

●Toxic appearance or lethargy.

●Moderate to severe respiratory distress (respiratory severity score ≥5 (table 1)). (See 'Severity assessment' above.)

●Apnea.

●Hypoxemia requiring oxygen therapy – Patients with oxygen saturation (SpO₂) levels that are persistently low (variably defined as <90 to <92 percent) generally warrant hospitalization for monitoring and oxygen therapy. However, SpO₂ levels should be interpreted in the context of other clinical signs. Transient self-resolving desaturation episodes are very common in infants with bronchiolitis, and this finding in isolation generally does not warrant hospitalization [17,19-22]. (See 'Supplemental oxygen' below.)

●Poor feeding and/or dehydration.

●Caregivers who are unable to care for the infant 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'.)

MODERATE TO SEVERE BRONCHIOLITIS (INPATIENT MANAGEMENT) — Supportive care is the mainstay of inpatient management of bronchiolitis, as discussed in the following sections.

Infection control precautions — Infants and children who are admitted to the hospital with bronchiolitis are typically managed initially with contact and droplet precautions (ie, gown and gloves, respiratory mask within three feet) if the viral etiology is unknown. If a specific viral pathogen is identified, precautions should be adjusted accordingly. This is discussed in detail separately. (See "Respiratory syncytial virus infection: Prevention in infants and children", section on 'Infection control in the health care setting' and "Infection prevention: Precautions for preventing transmission of infection".)

Monitoring — Monitoring for patients hospitalized for bronchiolitis includes:

●Monitoring of heart rate and respiratory rate – These can be monitored continuously or with intermittent measurements. Continuous monitoring is appropriate for patients with severe illness (especially those requiring pediatric intensive care unit [PICU] care and/or noninvasive ventilation [NIV]) and patients who have had documented apnea or are at risk for apnea (preterm infants and infants <2 months old).

●Pulse oximetry – We suggest continuous pulse oximetry initially in all patients who require oxygen therapy and/or NIV support. As the clinical course improves and the patient no longer requires supplemental oxygen, pulse oximetry can be changed from continuous monitoring to intermittent measurements [23,24].

●Regular assessments of the infant's respiratory status – This includes examination and auscultation to promptly recognize signs of worsening respiratory insufficiency (eg, increasing tachypnea, poor lung aeration, nasal flaring, retractions, grunting).

●Monitoring fluid intake and output – Fluid intake and urine output should be recorded in all infants and children hospitalized for bronchiolitis. (See 'Fluid and nutrition management' below.)

Other assessments that are not routinely performed in all patients, but may be warranted in select circumstances, include:

●In patients with severe distress, especially those who appear to be tiring, blood gas analysis may be warranted to assess for respiratory acidosis (ie, partial pressure of carbon dioxide [PCO₂] >45 mmHg).

●In children who do not improve as expected, chest radiographs may be helpful in excluding other conditions in the differential diagnosis (eg, pneumonia, foreign body aspiration, heart failure) [1]. (See "Bronchiolitis in infants and children: Clinical features and diagnosis", section on 'Differential diagnosis'.)

Fluid and nutrition management — Infants and children with bronchiolitis may have difficulty maintaining adequate hydration because of increased needs (related to fever and tachypnea) and poor oral intake (related to tachypnea and respiratory distress).

Patients who are hospitalized for bronchiolitis can be allowed to feed by mouth if their respiratory status permits. Providing small frequent feedings is a helpful strategy to maintain adequate hydration. Intravenous (IV) fluid hydration may be required if [1,25]:

●Oral intake is insufficient, or

●Respiratory distress is severe enough to make oral feeding unsafe due to risk of aspiration

For patients with severe distress (respiratory severity score [RSS] ≥9 (table 1)), we generally withhold feeds initially and provide IV hydration. As the infant's work of breathing improves, feeds can be gradually introduced as tolerated. Use of high-flow nasal cannula (HFNC) is not a contraindication to oral feeding [26,27].

Enteral feeding via an orogastric or nasogastric tube is an option for patients who cannot feed by mouth [10,28-31]. (See "Overview of enteral nutrition in infants and children", section on 'Indications for enteral nutrition' and "High-flow nasal cannula oxygen therapy in children", section on 'Cannula selection'.)

For patients requiring IV hydration, we generally used isotonic fluids (eg, normal saline or lactated Ringer) at a normal maintenance rate. Excessive fluid administration should be avoided, since it may lead to pulmonary congestion and worsening respiratory status [32]. (See "Maintenance intravenous fluid therapy in children".)

Fluid intake and urine output should be monitored. Patients with bronchiolitis are at risk for inappropriate secretion of antidiuretic hormone (ADH), which can lead to fluid retention and hyponatremia [33-35]. (See "Pathophysiology and etiology of the syndrome of inappropriate antidiuretic hormone secretion (SIADH)", section on 'Pulmonary disease'.)

Patients who remain on IV hydration for more than 48 hours should have serum electrolytes measured. Electrolytes should be measured sooner if there is clinical concerns for inappropriate ADH secretion (ie, fluid retention, low urine output).

Fever management — Fever can increase tachypnea and work of breathing in infants with bronchiolitis, and it contributes to insensible fluid loss. Thus, fever should be promptly treated with antipyretic therapy (eg, acetaminophen [paracetamol] or ibuprofen).

Neonates <29 days of age who develop fever (temperature ≥38°C [100.4°F]) generally warrant evaluation for bacterial illness and empiric antibiotic therapy pending culture results. This is discussed separately. (See "The febrile neonate (28 days of age or younger): Outpatient evaluation and initial management".)

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 oxygen saturation (SpO₂) >90 to 92 percent. Infants with more severe distress may require advanced respiratory support, with HFNC or other NIV support. Rarely, endotracheal intubation may be necessary for the most severely affected patients.

Supplemental oxygen — Patients with hypoxemia should receive supplemental oxygen by nasal cannula, face mask, or hood. Variable thresholds are used for starting oxygen therapy in infants with bronchiolitis, most commonly SpO₂ <90 to <92 percent.

Data are lacking to support the use of a specific SpO₂ cutoff value. In our practice, we target an SpO₂ ≥92 percent. Other experts may use different thresholds. For example, the American Academy of Pediatrics (AAP) practice guideline suggests SpO₂ <90 percent as the threshold to start supplemental oxygen [1].

However, variability in the accuracy of oximeters, particularly in the setting of concomitant fever and/or acidosis, favor the use of a higher cutoff value. In addition, studies have shown that skin pigmentation can impact pulse oximetry measurements, resulting in falsely elevated readings ("hidden hypoxemia") in individuals with darker skin pigmentation. (See "Pulse oximetry", section on 'Skin pigmentation'.)

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 [36]. 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 preterm infants and those with underlying conditions (eg, hemodynamically significant heart disease, bronchopulmonary dysplasia). (See 'Monitoring' above.)

Additional details regarding oxygen delivery systems are provided separately. (See "Continuous oxygen delivery systems for the acute care of infants, children, and adults".)

Noninvasive ventilation — Although standard oxygen therapy is sufficient for most infants and children with bronchiolitis who require supplemental oxygen, patients who have considerable work of breathing may benefit from NIV. NIV modalities that are commonly used in the management of bronchiolitis include HFNC, continuous positive airway pressure (CPAP), and bilevel positive airway pressure (BPAP) [37]. These modalities 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 [38-43]. Successful therapy with NIV avoids the adverse effects of endotracheal intubation (eg, laryngeal injury, ventilator-induced lung injury, ventilator-associated pneumonia, narcotic dependence and withdrawal) [44].

Infants and children who require NIV support are usually managed in a PICU or intermediate care unit. However, some institutions have protocols for using HFNC on the general ward, which appear to be safe [40,45-47]. A detailed discussion of critical care respiratory interventions for infants and young children with bronchiolitis is beyond the scope of this review. Additional details regarding use of HFNC and other NIV modalities in infants and children are provided separately. (See "High-flow nasal cannula oxygen therapy in children" and "Noninvasive ventilation for acute and impending respiratory failure in children".)

High-flow nasal cannula — For infants and children with bronchiolitis who have failed standard oxygen therapy and continue to have increased respiratory effort and/or hypoxemia, we suggest HFNC as the first-line NIV modality. These patients are at risk for respiratory failure and HFNC support may avoid the need for intubation. We prefer HFNC over CPAP and BPAP in most cases because HFNC appears to be equally effective and is generally well tolerated, simpler to use, and has lower risk of adverse events. Ideally, HFNC should be initiated before the infant shows signs of tiring [48].

●Initiation – HFNC is relatively simple to initiate. After an appropriately sized nasal cannula and circuit is selected for the patient, the clinician can determine delivery settings, including air temperature, flow rate, and fraction of inspired oxygen (FiO₂) (figure 1). Initial flow rates and FiO₂ vary by age/size of the patient and degree of hypoxemia. Guidance for flow settings according to patient weight are summarized in the table (table 3). Additional details are provided separately. (See "High-flow nasal cannula oxygen therapy in children", section on 'Initiation'.)

●Contraindications – Contraindications to HFNC include abnormalities of the face or airway that preclude an appropriate-fitting nasal cannula [49]. Relative contraindications include lethargy or agitation, vomiting, excessive secretions, and bowel obstruction. (See "High-flow nasal cannula oxygen therapy in children", section on 'Contraindications'.)

●Complications – Complications of HFNC include abdominal distension, aspiration, barotrauma, and pneumothorax (rare) [49]. However, the risk of pneumothorax is lower with HFNC than with other forms of positive pressure ventilation (eg, CPAP, BPAP, or invasive mechanical ventilation). In studies comparing HFNC and CPAP, the risk of adverse events, particularly nasal trauma, was lower with HFNC than CPAP [43,50]. (See "High-flow nasal cannula oxygen therapy in children", section on 'Complications'.)

●Monitoring response – After starting HFNC, the infant's respiratory status should be monitored closely. A positive response is indicated by improvement in tachypnea and work of breathing. If the infant continues to have significant distress and/or hypoxemia, the flow and FiO₂ settings should be adjusted as needed (table 3). SpO₂ is a poor indicator of success or failure of HFNC since infants with impending respiratory failure can have adequate SpO₂ despite having poor lung aeration and inadequate ventilation. If there is concern that the infant is failing HFNC, blood gas analysis should be performed to assess for respiratory acidosis (ie, PCO₂ >45 mmHg). (See 'Monitoring' above.)

For infants who continue to have significant respiratory distress despite maximizing HFNC, we suggest transitioning to CPAP or BPAP. We generally use BPAP since CPAP may not provide sufficient support for infants who fail HFNC. (See 'CPAP and BPAP' below.)

●Supporting evidence – The use of HFNC in patients with bronchiolitis is supported by observational studies and randomized trials [40,41,43,50-57].

•Studies comparing HFNC versus standard oxygen therapy – A 2019 systematic review identified six trials involving 1885 patients hospitalized for bronchiolitis who were randomly assigned to HFNC or standard oxygen therapy; none of the trials were blinded [50]. Different trials reported different outcomes, which precluded pooling of all six trials together. In a meta-analysis of four trials (1788 patients) that reported respiratory rate, HFNC had little to no effect on respiratory rate (mean difference 2 breaths per minute [bpm] slower in the HFNC group) [50]. In the two trials (1526 patients) that reported intubation rates, few patients in either group required intubation (8 patients in the HFNC group; 4 in the control group) [50].

An important limitation of these data is that the trials mostly enrolled patients with nonsevere bronchiolitis. For example, the two largest trials involved patients who were admitted to the general ward [45,58]. In one trial, the mean respiratory rate at time of randomization was 52 bpm, indicating only mild respiratory illness [45]; in the other trial, the median clinical severity score at the time of randomization was 2.6 on the modified Woods scale (which ranges from 0 to 14, with scores <5 indicating mild symptoms) [58]. The exclusion of severely affected patients from these trials is also reflected by the low intubation rates. As such, these trials did not directly evaluate the efficacy of HFNC as it is most commonly used (namely, for patients with severe respiratory distress). Rather, they were designed to address the question of whether broad use of HFNC in all patients requiring oxygen therapy ("preemptive" HFNC) effectively reduces intubation rates and/or hospital length of stay. Preemptive use of HFNC is discussed in greater detail below.

A subsequent trial that was not included in the meta-analysis enrolled 60 patients who were admitted to the PICU with moderate to severe bronchiolitis (median clinical severity score of 10 on the Wang score, which ranges from 4 to 12 points, with scores >8 indicating severe distress) [57]. Patients were randomly assigned to HFNC or blended oxygen via facemask. At six hours after starting therapy, patients in the HFNC group had greater improvements in respiratory rate and heart rate. Both PICU length of stay and hospital length of stay were one day shorter in the HFNC group. No patients in either group required intubation.

Additional support for use of HFNC in patients with severe bronchiolitis comes from retrospective and prospective observational studies reporting dramatic reductions in the need for intubation in patients with bronchiolitis following the introduction of HFNC [40,51-53,55].

•Studies comparing HFNC versus CPAP – In a randomized trial involving 573 infants and children with severe bronchiolitis who were randomly assigned to HFNC or CPAP, both groups had similar rates of intubation (15 versus 16 percent) and similar duration of respiratory support (median duration 53 versus 48 hours, respectively) [43]. However, patients in the HFNC group were less likely to require sedation and less frequently experienced nasal trauma. Both PICU length of stay and hospital length of stay were shorter in the HFNC group. A meta-analysis of four earlier small trials (total 264 patients) reported similar findings [50]. Observational studies have reported little to no differences in clinical outcomes of patients managed with HFNC or CPAP [54].

•Studies evaluating "preemptive" HFNC – Several studies have investigated the use of HFNC in patients with oxygen requirement but with otherwise nonsevere symptoms who are managed on the general ward (ie, "preemptive" HFNC) [45,58]. Based on the available data, this approach does not appear to decrease the length of hospitalization, duration of oxygen therapy, or need for intubation [42,50,59-62]. One large trial found that preemptive HFNC initiated on the ward reduced the need for transfer to the PICU [45]; while a second trial reported similar rates of PICU admission in patients managed with or without preemptive HFNC [58]. These studies were carried out at centers with protocols in place for using HFNC on the general wards, which is not universal practice. In many centers, need for HFNC automatically triggers PICU admission. Regardless of the setting of care (general ward versus PICU), routine use of HFNC for all patients with an oxygen requirement would likely put a strain on respiratory care resources at many hospitals. The additional cost and resources necessary to support this practice do not appear to be justified given the lack of apparent benefit. Thus, we suggest using HFNC only in patients who have a clinical need for this therapy (ie, significant respiratory distress).

Additional studies supporting use of HFNC for pediatric respiratory failure more broadly are discussed separately. (See "High-flow nasal cannula oxygen therapy in children", section on 'Comparison with other modes of oxygen delivery'.)

CPAP and BPAP — CPAP and BPAP are commonly used for patients with progressive respiratory insufficiency despite HFNC. These modalities may also be used as the initial mode of NIV support, particularly in patients with very severe symptoms. However, for most patients requiring NIV, we prefer HFNC as the initial modality for the reasons outlined above. (See 'High-flow nasal cannula' above.)

Similar to HFNC, NIV with CPAP or BPAP aims to avoid the need for endotracheal intubation and, as is true for HFNC, these modalities are optimally applied before the patient shows signs of tiring.

Observational studies and a few small randomized trials 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 intensive care unit [41,44,63-73]. Trials comparing CPAP and HFNC are discussed above. (See 'High-flow nasal cannula' above.)

Use of BPAP for management of bronchiolitis has been increasing at many centers. This practice is supported by observational studies [72,74,75]; clinical trials are lacking. In infants and small children, BPAP can be administered with an infant nasal interface (picture 1) [76], which is generally better tolerated than nasal masks (picture 2) or facial masks (picture 3). The practice of using nasal cannula BPAP (also called nasal intermittent positive pressure ventilation) in infants in the PICU setting is extrapolated from neonatal practice. Additional details are provided separately. (See "Noninvasive ventilation for acute and impending respiratory failure in children" and "Respiratory support, oxygen delivery, and oxygen monitoring in the newborn", section on 'Nasal intermittent positive pressure ventilation'.)

Endotracheal intubation — Infants who have ongoing or worsening severe distress despite a trial of NIV may require endotracheal intubation and mechanical ventilation. Intubation may also be necessary in infants with frequently recurrent episodes of apnea. 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, venous, or capillary blood gases obtained in infants with impending respiratory failure often reveal significant respiratory acidosis (ie, PCO₂ >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 "Technique of emergency endotracheal intubation in children".)

Interventions for airway clearance

Nasal suctioning — For infants and children hospitalized with bronchiolitis, saline nose drops and mechanical aspiration of the nares may help to relieve partial upper airway obstruction. This often reduces work of breathing and makes it easier for the infant to feed. In a retrospective study of 740 infants (2 to 12 months of age) hospitalized with bronchiolitis, those who had lapses of >4 hours between mechanical suctioning had longer hospital stay than those without lapses in suctioning (2.6 versus 1.6 days) [77].

Deep suctioning of the oro- or nasopharynx with a suction catheter is not necessary in most cases [1]. Catheter suctioning of the nasopharynx is traumatic and may produce edema, which may worsen nasal obstruction rather than relieving it. However, for severely affected infants managed in the PICU setting, careful deep suctioning by trained nursing staff is reasonable if there is concern for upper airway obstruction from copious secretions.

In the same retrospective study of 740 patients hospitalized with bronchiolitis, those who received frequent deep suctioning during the first 24 hours of admission had longer hospital stay compared with patients who received no or infrequent deep suctioning [77]. Given the observational nature of these data, it is possible that the association may be explained, at least in part, by confounding (ie, infants requiring frequent suctioning are likely sicker and their longer hospital stay may reflect their greater severity of illness rather than a negative impact of deep suctioning), though the study did attempt to control for confounding.

Chest physiotherapy — Chest physiotherapy (CPT) is not necessary for most patients with uncomplicated bronchiolitis. In patients with nonsevere bronchiolitis, the use of CPT is discouraged because it may increase the infant's discomfort and distress. However, CPT may be warranted in infants and children requiring PICU care, particularly intubated patients, and in children with comorbidities associated with difficulty clearing respiratory secretions (eg, neuromuscular disorders, cystic fibrosis) [12]. (See "Atelectasis in children", section on 'Airway clearance techniques'.)

A systematic review identified 17 small randomized trials investigating use of CPT in patients with bronchiolitis [78]. CPT techniques and frequency varied considerably and different trials reported different outcomes, which precluded pooling of all 17 trials together. In a meta-analysis of seven trials that reported clinical severity scores, CPT modestly reduced clinical severity (standardized mean difference 0.43, 95% CI 0.13-0.73) [78]. Only one trial reported time to recovery, which was shorter in the CPT group compared with control (2.6 versus 4.4 days) [79].

Nebulized hypertonic saline — Practice varies regarding the use of nebulized hypertonic saline in patients with bronchiolitis. At the authors' center, we do not routinely use nebulized hypertonic saline in hospitalized patients. Other centers may trial hypertonic saline in patients with moderate to severe distress that persists despite suctioning and NIV or in those with a prolonged hospital stay without improvement over the first 48 hours of admission.

The 2015 National Institute for Care Excellence bronchiolitis guideline recommends against the use of nebulized hypertonic saline in children with bronchiolitis [12]. 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].

In a meta-analysis of 21 trials (2479 infants) comparing nebulized hypertonic saline with nebulized 0.9% saline or no nebulized treatment, nebulized hypertonic saline reduced clinical severity scores and modestly reduced length of hospital stay (mean difference 10 hours, 95% CI 3-17 hours) [80]. In trials performed in the emergency department (ED) setting (eight trials, 1760 patients), nebulized hypertonic saline modestly reduced the need for hospitalization (28 versus 34 percent; relative risk 0.87, 95% CI 0.78-0.97). Adverse events due to hypertonic saline administration were uncommon.

In a network meta-analysis of 150 randomized trials evaluating various interventions for bronchiolitis (including hypertonic saline, HFNC, bronchodilators, glucocorticoids, heliox, and numerous other interventions), nebulized hypertonic saline was found to be among the most effective interventions for reducing hospital length of stay, though the absolute benefit relative to placebo was small (mean difference 15 hours) [81].

Limited role of bronchodilator therapy — Bronchodilator therapy generally does not play a significant role in the management of bronchiolitis, particularly in patients without severe symptoms or wheezing. However, for patients with severe respiratory distress and wheezing, we suggest a trial of bronchodilator therapy.

●Dosing and administration – When the decision is made to trial bronchodilator therapy, we suggest albuterol, administered either via nebulizer (0.15mg/kg [minimum 2.5 mg; maximum 5 mg] diluted in 2.5 to 3 mL saline given over 5 to 15 minutes) or via metered dose inhaler with spacer and face mask (four to six puffs). We prefer albuterol over epinephrine because if the child responds, albuterol is more appropriate for administration in the home setting.

●Assessing response – The response to bronchodilator therapy should be assessed by evaluating the child's respiratory status before and up to one hour after treatment [82]. A positive response is signaled by improvement in wheezing, better lung aeration, slower respiratory rate, and reduced work of breathing. In some cases, it may be difficult to definitively categorize the patient as responsive or nonresponsive, particularly if multiple interventions are provided simultaneously. In such cases, clinicians should use their best judgement as to whether to continue the medication. If there is an apparent clinical response to albuterol, it can be given every four to six hours as needed and discontinued when the signs and symptoms of respiratory distress improve [83]. If there is no apparent response to albuterol, it should be discontinued.

●Evidence – The use of bronchodilator therapy (inhaled or oral) in patients with bronchiolitis has been studied in randomized trials and meta-analyses [83-88]. The available evidence suggests that bronchodilators may provide modest short-term clinical improvement, but they do not appear to hasten recovery. When used in the outpatient or ED setting, they do not appear to reduce the need for hospitalization [85]. Given the modest clinical benefit and the potential for adverse effects from these medications [89], they should not be used routinely.

In a meta-analysis of 11 placebo-controlled trials involving 495 patients hospitalized for bronchiolitis, bronchodilator therapy had little to no impact on oxygen saturation (mean difference 0.6 percent), though in some trials the clinical severity score was more likely to improve in patients treated with bronchodilator therapy [85]. Duration of hospitalization was similar in both groups.

It is important to recognize that most of these trials excluded children with severe disease or respiratory failure, and thus it is uncertain if these findings apply to severely affected patients. In addition, a subset of young children with the clinical syndrome of bronchiolitis may have virus-induced wheezing or asthma and may respond to bronchodilator therapy. In particular, children with prior episodes of wheezing, rhinovirus bronchiolitis, older age (>15 months), and family history of asthma or atopy are more likely to respond to albuterol compared with younger infants with first-time wheezing in the setting of respiratory syncytial virus (RSV) bronchiolitis [90]. (See "Treatment of recurrent virus-induced wheezing in young children", section on 'Episodic therapy'.)

Multiple professional groups recommend that bronchodilators not be used routinely in the management of bronchiolitis [1,10,12,13,91]. (See 'Society guideline links' below.)

Limited role of glucocorticoids — Glucocorticoid therapy does not play a role in the routine management of bronchiolitis. Use of glucocorticoids is limited to patients in whom there is a clinical suspicion for underlying airway reactivity or asthma and respond to albuterol.

●Patients with first-time episode of bronchiolitis – For otherwise healthy infants and young children with a first episode of bronchiolitis, we suggest not using systemic or inhaled glucocorticoids [1,91,92]. Glucocorticoids do not appear to reduce the need for hospitalization for those seen in the outpatient or ED setting, nor do they reduce the duration of hospitalization for those who require inpatient care [92].

Although the anti-inflammatory effects of glucocorticoids theoretically reduce airway obstruction by decreasing bronchiolar swelling, most studies show little to no benefit of glucocorticoid therapy in patients with bronchiolitis. In a meta-analysis of eight trials (1762 patients) evaluating glucocorticoid therapy for bronchiolitis in the ED or outpatient setting, hospital admission rates were similar in the glucocorticoid and placebo groups (15 versus 16 percent; risk ratio 0.92, 95% CI 0.78-1.08) [92]. In a meta-analysis of trials involving inpatients (eight trials, 633 patients), duration of hospitalization was similar in both groups (mean difference four hours shorter in the glucocorticoid group; 95% CI nine hours shorter to one hour longer) [92].

●Patients with recurrent episodes of wheezing – For patients with recurrent episodes of wheezing, there is some overlap between the clinical syndrome of bronchiolitis and viral-induced exacerbation of underlying airway reactivity or asthma. It is reasonable to use glucocorticoid therapy if there is clinical concern for underlying asthma. Patients who are most likely to benefit from glucocorticoid therapy are children >12 months of age who have had multiple prior episodes of wheezing, especially if there is a clear response to albuterol and/or a personal or family history of asthma or atopic diseases. Management of asthma in the ED and inpatient settings is discussed in detail separately. (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".)

Although patients with acute asthma exacerbations clearly benefit from glucocorticoid therapy, the role of glucocorticoid therapy in young children with recurrent viral-induced wheezing is less certain. The available studies have not consistently shown a benefit of systemic glucocorticoid therapy in this setting, as discussed separately. (See "Treatment of recurrent virus-induced wheezing in young children", section on 'Antiinflammatory therapy'.)

Limited role of antibiotics — Antibiotics should not be used routinely in the treatment of bronchiolitis, which is almost always caused by viruses [93]. (See "Bronchiolitis in infants and children: Clinical features and diagnosis", section on 'Viral etiology'.)

Use of antibiotic therapy is limited to the following circumstances:

●Neonates ≤28 days old with fever (temperature ≥38°C [100.4°F]) and symptoms and signs of bronchiolitis have the same risk for invasive bacterial illness as febrile neonates without bronchiolitis. These infants should undergo appropriate evaluation and receive empiric antibiotics pending cultures, as discussed separately. (See "The febrile neonate (28 days of age or younger): Outpatient evaluation and initial management", section on 'Other viral infections'.)

●Occasionally, concomitant or secondary bacterial infections may occur in patients with bronchiolitis, most commonly otitis media or bacterial pneumonia. Coexisting bacterial infections should be treated in the same manner as they would be treated in the absence of bronchiolitis. (See "Acute otitis media in children: Treatment" and "Pneumonia in children: Inpatient treatment".)

Therapies of unproven or uncertain benefit — We suggest not using any of the following therapies in the management of bronchiolitis:

●Leukotriene inhibitors – We suggest not using montelukast or other leukotriene inhibitors for the treatment of bronchiolitis. Studies measuring levels of leukotrienes from nasal lavage samples of patients with bronchiolitis suggest that leukotrienes may play a role in airway inflammation in bronchiolitis [94-96]. However, in a meta-analysis of two randomized trials involving 136 patients with bronchiolitis who were assigned to a leukotriene inhibitor or placebo, both groups had similar clinical severity scores and similar duration of hospitalization [97]. We also suggest not using leukotriene inhibitors during recovery following hospitalization for bronchiolitis in an attempt to prevent subsequent wheezing episodes since this does not appear to be effective, as discussed below. (See 'Prevention of recurrences' below.)

●Heliox – We suggest not routinely using heliox (a 70/30 or 80/20 mixture of helium and oxygen, respectively) in the treatment of bronchiolitis. Based on the available data, heliox does not appear to hasten recovery or reduce the need for advanced respiratory support [98]. In addition, the administration of heliox is cumbersome, particularly when used in conjunction with other modalities such as HFNC. In a meta-analysis of six randomized trials involving a total of 560 patients with bronchiolitis who were assigned to heliox or a standard air-oxygen mixture, both groups had similar rates of CPAP usage (15 versus 17 percent, respectively) and need for intubation (7 versus 5 percent), and both groups had similar hospital duration [98]. (See "Physiology and clinical use of heliox", section on 'Technical issues'.)

●Monoclonal antibody therapy – RSV-specific monoclonal antibody agents (nirsevimab or palivizumab) are available and commonly used for prevention of severe RSV disease in infants. However, these agents are not used in the treatment of RSV infection. In a randomized trial, the duration of hospitalization was similar for infants who received palivizumab or placebo (29 versus 30 hours, respectively) [99]. Earlier trials also failed to detect a benefit of palivizumab or other antibody products (ie, immune globulin with high neutralizing activity against RSV [RSV-IVIG], which is no longer available) [100]. Nirsevimab has not been studied in this setting. The use of nirsevimab and palivizumab for preventing RSV infections in infancy is discussed separately. (See "Respiratory syncytial virus infection: Prevention in infants and children".)

●Ribavirin – Ribavirin is an antiviral agent with activity against RSV. It does not play any role in the routine management of RSV bronchiolitis in otherwise healthy children [101]. Its use is limited to immunocompromised patients with severe RSV infection, as discussed separately. (See "Respiratory syncytial virus infection: Treatment in infants and children", section on 'Ribavirin'.)

●Surfactant – For patients with bronchiolitis who require intubation and mechanical ventilation, surfactant therapy does not play any role in management. A meta-analysis of three small randomized trials involving mechanically ventilated infants with bronchiolitis did not detect a difference in duration of mechanical ventilation between those who did or did not receive surfactant therapy, though duration of PICU stay was shorter for surfactant-treated infants [102].

DISCHARGE CRITERIA — At a minimum, the following criteria should be met for discharge from the hospital or emergency department [10,12,18]:

●Tachypnea and work of breathing have improved; the respiratory rate should be <60 breaths per minute (bpm) for age <6 months, <55 bpm for age 6 to 11 months, and <45 bpm for age ≥12 months.

●The patient is stable while breathing ambient room air (for at least 12 hours in hospitalized patients). We generally prefer that hospitalized patients maintain oxygen saturation ≥90 percent in room air because this is predictive of continued improvement [103]. However, some observational studies suggest that adherence to strict pulse oximetry criteria is associated with increased health care utilization [17,19,20]. Clinicians should be aware that transient self-resolving episodes of mild desaturation are common in children with bronchiolitis and generally do not warrant ongoing hospitalization if the child is otherwise well-appearing and ready for discharge.

●The 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).

●Caregivers are confident they can provide care at home, including clear use of bulb suctioning to clear the infant's airway, if necessary.

●Education of the caregivers is complete. (see 'Anticipatory guidance' above and 'Information for patients' below)

The duration of hospitalization for bronchiolitis varies considerably, depending on the age of the patient, severity of illness, complications, and comorbidities. The usual duration is approximately two to three days for patients with an uncomplicated course [103-105]. The course may be prolonged in younger infants and those with comorbid conditions (eg, bronchopulmonary dysplasia) [106,107]. In addition, hospital length of stay tends to be shorter in patients with rhinovirus bronchiolitis compared with respiratory syncytial virus [104,105,108].

FOLLOW-UP AFTER DISCHARGE — Infants and children who have received treatment for bronchiolitis in the emergency department or inpatient setting should have outpatient follow-up within 48 hours.

Prior to discharge, we review indications for seeking medical care (worsening respiratory distress, decreasing fluid intake, no wet diapers for 12 hours, new fevers) [10,12]. (See "Patient education: Bronchiolitis and RSV in infants and children (Beyond the Basics)", section on 'When to seek help'.)

We inform caregivers that some children who have been admitted with bronchiolitis may experience recurrent wheezing with subsequent respiratory illnesses and we counsel caregivers to seek medical care if the child develops wheezing or breathing difficulty during subsequent upper respiratory infections [109]. (See 'Association with recurrent wheezing and asthma' below.)

We also recommend avoidance of smoke exposure and timely receipt of routine childhood immunizations, including influenza and pneumococcal vaccines. (See "Secondhand smoke exposure: Effects in children" and "Standard immunizations for children and adolescents: Overview".)

OUTCOME — Bronchiolitis is a self-limited illness and often resolves without complications in most previously healthy infants. Severely affected infants, especially preterm infants and those with underlying cardiopulmonary disease or immunodeficiency, are at increased risk for complications (eg, apnea, respiratory failure, secondary bacterial infection).

Typical disease course — For infants with uncomplicated bronchiolitis, the illness typically begins with upper respiratory tract symptoms (eg, nasal congestion and cough). Lower respiratory signs (wheezing, crackles) typically develop on days 2 to 3, peak on days 3 to 5, and then gradually resolve over the course of two to three weeks [110-112].

However, the duration of the illness can vary depending on the age of the patient, severity of illness, comorbidities (eg, prematurity, chronic pulmonary disease), and the causative agent [104]. The course may be prolonged in young infants (particularly those <12 weeks of age) and those with comorbid conditions (eg, bronchopulmonary dysplasia); these children are more likely to have severe disease requiring hospitalization and advanced respiratory support [106,107].

In a systematic review of four studies including 590 children with bronchiolitis who were seen in outpatient settings and not treated with bronchodilators, the mean time to resolution of cough ranged from 8 to 15 days [112]. 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 caregiver-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 [111].

Bronchiolitis-associated mortality — In resource-abundant countries, the risk of mortality due to respiratory syncytial virus (RSV) bronchiolitis is very low (<0.1 percent) [113]. Most RSV-related deaths occur in young infants (6 to 12 weeks), those who were born preterm, and those with underlying medical conditions (eg, cardiopulmonary disease, immune deficiency) [114-116].

Association with recurrent wheezing and asthma — Compared with children who never had bronchiolitis, those who were hospitalized for bronchiolitis in infancy, especially due to RSV and rhinovirus, have a three- to fourfold higher risk of having recurrent wheezing or asthma during the first decade of life [117-127].

Whether there is a causal relationship between bronchiolitis in infancy and development of asthma is uncertain. The association may be due to factors that predispose to both wheezing in infancy (bronchiolitis) and wheezing later in childhood (asthma). The risk of asthma is multifactorial, 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 infections in early childhood. These issues are discussed in greater detail separately. (See "Role of viruses in wheezing and asthma: An overview" and "Risk factors for asthma", section on 'Respiratory infections'.)

PREVENTION

Primary prevention

General strategies — Standard strategies to reduce the risk of bronchiolitis 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]. (See "Respiratory syncytial virus infection: Prevention in infants and children", section on 'General measures'.)

Vaccines and immunoprophylaxis — Vaccines and/or immunoprophylaxis agents are available for some of the causes of bronchiolitis:

●Respiratory syncytial virus – Strategies to prevent severe RSV infections in infancy include the following, which are discussed in detail separately:

•Maternal vaccination during pregnancy (see "Immunizations during pregnancy", section on 'Respiratory syncytial virus')

•Immunoprophylaxis with monoclonal antibodies (eg, nirsevimab, palivizumab) in the infant (see "Respiratory syncytial virus infection: Prevention in infants and children", section on 'Immunoprophylaxis')

●Influenza – Annual influenza vaccination is recommended for all infants and children ≥6 months of age. Household contacts of young children should also receive annual influenza vaccination. (See "Seasonal influenza in children: Prevention with vaccines" and "Seasonal influenza vaccination in adults".)

●COVID-19 – COVID-19 vaccination is recommended for all infants and children ≥6 months of age. (See "COVID-19: Vaccines", section on 'Children aged six months to four years'.)

●Other viruses – Vaccines to prevent other causes of bronchiolitis (rhinovirus, human metapneumovirus, and parainfluenza virus) are unavailable.

Prevention of recurrences — For infants and young children who have experienced an episode of bronchiolitis, strategies to prevent subsequent episodes are largely the same as for primary prevention. (See 'Primary prevention' above.)

We suggest not using inhaled glucocorticoids, azithromycin, or leukotriene inhibitors (eg, montelukast) to attenuate airway inflammation for the prevention of subsequent wheezing episodes in infants and children following their first episode of bronchiolitis. In randomized trials and meta-analysis, none of these interventions have been beneficial in reducing subsequent wheezing episodes [92,97,128-132]. However, some of these therapies may be appropriate for patients with recurrent viral-induced wheezing. Additional information on prevention of viral-induced wheezing is provided separately. (See "Treatment of recurrent virus-induced wheezing in young children", section on 'Preventive therapy'.)

The use of inhaled glucocorticoids and leukotriene inhibitors in patients with an established diagnosis of asthma is discussed separately. (See "Asthma in children younger than 12 years: Management of persistent asthma with controller therapies".)

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 5^th to 6^th 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 10^th to 12^th 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

●Severity assessment – For infants and young children with bronchiolitis, the severity assessment informs management decisions (table 1) (see 'Severity assessment' above):

•Mild bronchiolitis is characterized by mild lower respiratory tract signs (wheezing and/or crackles) with little to no respiratory distress and normal activity level.

•Moderately severe bronchiolitis is characterized by moderate tachypnea and respiratory distress (ie, mild to moderate retractions without grunting or head bobbing), no apnea, and normal level of alertness.

•Severe bronchiolitis is characterized by persistent tachypnea, considerable respiratory distress (ie, retractions, grunting, nasal flaring, head bobbing), apnea, and/or poor responsivity.

●Management of mild bronchiolitis – Infants and children with mild bronchiolitis (respiratory severity score [RSS] <5 (table 1)) 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. (See 'Mild bronchiolitis (outpatient management)' above.)

●Indications for hospitalization – Hospitalization is generally indicated for infants and young children with any of the following (see 'Indications for hospitalization' above):

•Toxic appearance or lethargy

•Moderate to severe respiratory distress

•Apnea

•Hypoxemia requiring oxygen therapy

•Poor feeding and/or dehydration

•Caregivers who are unable to care for the infant at home

●Management of moderate to severe bronchiolitis – Infants and children with moderate to severe bronchiolitis (RSS ≥5 (table 1)) require evaluation in the emergency department (ED) and usually require supportive care in the inpatient setting. (See 'Emergency department management' above and 'Moderate to severe bronchiolitis (inpatient management)' above.)

Supportive care is the mainstay of management of bronchiolitis in the ED and inpatient settings. This includes:

•Respiratory support – Patients with persistent hypoxemia should receive supplemental oxygen as needed. For patients with severe distress, we suggest high-flow nasal canula (HFNC) as the initial mode of respiratory support rather than other noninvasive ventilation (NIV) modalities (Grade 2B). Rarely, endotracheal intubation may be necessary for the most severely affected patients. (See 'Supplemental oxygen' above and 'High-flow nasal cannula' above and 'Endotracheal intubation' above.)

•Fluids – Patients with a history and/or clinical findings suggestive of dehydration should receive intravenous hydration, as appropriate. (See 'Fluid and nutrition management' above and "Treatment of hypovolemia (dehydration) in children in resource-abundant settings" and "Maintenance intravenous fluid therapy in children".)

•Nasal suctioning – Most patients with moderate to severe symptoms require intermittent nasal suctioning. (See 'Nasal suctioning' above.)

•Trial of inhaled bronchodilator – For most patients with a first episode of nonsevere bronchiolitis, we suggest not routinely administering inhaled bronchodilators (albuterol or epinephrine) (Grade 2B). However, for patients with severe respiratory distress and wheezing, we suggest a trial of bronchodilator therapy (Grade 2C). We suggest albuterol (salbutamol) rather than nebulized epinephrine for this purpose (Grade 2C). Other centers may use epinephrine. If the infant responds, additional treatments can be provided as needed. If the infant does not respond, bronchodilator therapy should be discontinued. (See 'Limited role of bronchodilator therapy' above.)

•Other interventions that are used selectively – The following interventions are not routine but may be used in select circumstances:

-We do not routinely treat with nebulized hypertonic saline at our center. However, some centers may use nebulized hypertonic saline in patients with ongoing moderate to severe symptoms despite nasal suctioning and NIV. (See 'Nebulized hypertonic saline' above.)

-We recommend not using systemic glucocorticoids routinely in the treatment of previously healthy infants hospitalized with a first episode of bronchiolitis (Grade 1B). Use of glucocorticoids is generally limited to patients in whom there is clinical suspicion for underlying airway reactivity or asthma (eg, recurrent episodes of wheezing, especially if there is a personal or family history of asthma or atopic diseases). (See 'Limited role of glucocorticoids' above and "Acute asthma exacerbations in children younger than 12 years: Emergency department management", section on 'Systemic glucocorticoids'.)

-Antibiotics are indicated only in febrile neonates (age ≤28 days) or if there is evidence of a coexisting bacterial infection. (See 'Limited role of antibiotics' above and "The febrile neonate (28 days of age or younger): Outpatient evaluation and initial management".)

●Discharge criteria – At a minimum, the following criteria should be met for discharge from the hospital or ED (see 'Discharge criteria' above and 'Anticipatory guidance' above):

•Tachypnea and work of breathing have improved

•The patient is stable while breathing ambient room air

•The patient has adequate oral intake to prevent dehydration

•Resources at home are adequate to support the use of any necessary home therapies

•Caregivers are confident they can provide care at home, including clear use of bulb suctioning to clear the infant's airway, if necessary

•Education of the caregivers is complete

●Prevention – Strategies to prevent bronchiolitis include hand hygiene, minimizing passive exposure to cigarette smoke, avoiding contact with individuals with respiratory tract infections, and vaccination or immunoprophylaxis against the viruses that cause bronchiolitis. (See 'Prevention' above.)

Prevention of respiratory syncytial virus infection is discussed in detail separately. (See "Respiratory syncytial virus infection: Prevention in infants and children".)

ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges Ann R Stark, MD, who contributed to earlier versions of this topic review.