17:I[462708,["/_next/static/chunks/3yo3kiro3bmlp.js","/_next/static/chunks/3vr2wvd8f2efb.js","/_next/static/chunks/2vtmb68_vu-9t.js","/_next/static/chunks/2s8mt6_8wrpfo.js","/_next/static/chunks/3vkulz2i3l61y.js","/_next/static/chunks/1cqw2i1silz0i.js","/_next/static/chunks/14dbm3lm_t629.js","/_next/static/chunks/335_v2mb569ld.js","/_next/static/chunks/3ykn5ops9bft5.js","/_next/static/chunks/3cmavum774kjt.js","/_next/static/chunks/3th-0-a2xf9qs.js","/_next/static/chunks/0p0xpwde6kzmv.js","/_next/static/chunks/401-sxxnzbtf_.js","/_next/static/chunks/0wywtv698a1v0.js","/_next/static/chunks/2botzqwpnrzyj.js"],"ArticleReader"] 18:T476a,## Summary Acute bronchiolitis is a clinical syndrome of viral lower-respiratory-tract infection in infants and young children, most commonly during the first year of life. A typical illness begins with coryza and cough, followed by tachypnea, increased work of breathing, wheeze and/or crackles, reduced feeding, and sometimes hypoxemia or apnea.[1-3] Diagnosis is usually clinical. **Routine chest radiography, blood tests, and viral testing are not indicated in an otherwise typical case.** Nonspecific atelectatic or interstitial changes on chest radiography can be misinterpreted as bacterial pneumonia and drive unnecessary antibiotic use.[1,2] Treatment is predominantly supportive: minimize distress, clear nasal secretions when obstruction interferes with breathing or feeding, maintain hydration and nutrition, provide oxygen for persistent hypoxemia, and escalate respiratory support when the child is tiring or failing lower-level support.[1-4] For most infants aged **6 weeks or older**, NICE and the 2025 Australasian guideline use persistent room-air **SpO₂ <90%** as the threshold for supplemental oxygen in hospital. A higher threshold of **<92%** is used for infants younger than 6 weeks and for children with important underlying conditions in NICE guidance.[1,3] Clinical trajectory, apnea, feeding, work of breathing, age, and comorbidity remain essential; a single saturation reading should not determine admission or discharge. Do **not** routinely use salbutamol/albuterol, nebulized epinephrine, systemic or inhaled corticosteroids, hypertonic saline, ipratropium, montelukast, antibiotics without a bacterial indication, or chest physiotherapy for typical bronchiolitis.[1-3] The updated Australasian guidance reserves a possible corticosteroid-plus-epinephrine strategy for selected critically ill infants under specialist intensive-care protocols; this should not be extrapolated to routine ward or emergency care.[3] High-flow nasal cannula (HFNC) can reduce escalation from conventional oxygen in hospitalized infants, but contemporary guidance does **not** support routine first-line HFNC for moderate bronchiolitis. Start with low-flow oxygen when oxygen is needed; use HFNC when persistent hypoxemia or respiratory distress remains despite appropriate conventional support, according to local pediatric respiratory protocols.[3,4] Impending respiratory failure is suggested by recurrent apnea, exhaustion or decreasing respiratory effort, altered responsiveness, poor air entry, persistent/worsening hypoxemia despite support, rising carbon dioxide with acidemia, or hemodynamic instability. These findings require urgent senior pediatric/critical-care review.[1-3] RSV prevention has changed substantially. Current 2026 American Academy of Pediatrics (AAP) policy recommends seasonal long-acting RSV monoclonal-antibody immunization for eligible infants younger than 8 months who are not adequately protected by maternal RSV vaccination, and for selected high-risk children aged 8–19 months entering a second RSV season.[5] Prevention does not treat established bronchiolitis. > **Clinical pearl:** The sickest infant may become quieter rather than more visibly distressed. Falling respiratory effort with persistent tachycardia, hypoxemia, poor air entry, or altered responsiveness suggests fatigue, not recovery. ## Definition and typical course Bronchiolitis is an acute viral small-airway illness in a baby or young child, usually younger than 2 years, with an upper-respiratory prodrome followed by lower-airway findings and no better alternative diagnosis. Definitions differ by jurisdiction; the disease is most typical in infants.[1,2] A common trajectory is: 1. rhinorrhea and nasal congestion; 2. cough and reduced feeding; 3. tachypnea with subcostal/intercostal recession; 4. diffuse crackles and/or wheeze; 5. variable hypoxemia and feeding intolerance. Symptoms often peak around days 3–5, but management should follow the individual child's physiology rather than a calendar rule.[1] ## Etiology Respiratory syncytial virus (RSV) is the leading cause of severe infant bronchiolitis. Other causes include rhinovirus, human metapneumovirus, influenza, parainfluenza, adenovirus, seasonal coronaviruses, and SARS-CoV-2. Coinfection can occur. Identifying the virus usually does not change treatment. Viral testing may be useful when it changes cohorting, infection-control practice, influenza antiviral treatment, or management of an immunocompromised child. ## Pathophysiology Viral infection injures ciliated airway epithelium and produces mucosal edema, mucus, and cellular debris. Because infant bronchioles are narrow, modest swelling markedly increases resistance. Partial obstruction produces air trapping; complete obstruction causes distal atelectasis. Ventilation-perfusion mismatch produces hypoxemia while tachypnea and nasal obstruction impair feeding.[2] Young infants are vulnerable because of: - small airway caliber; - compliant chest wall; - limited respiratory reserve; - dependence on nasal breathing; - immature respiratory control and apnea risk; - limited ability to compensate for reduced intake. ## Risk factors for severe disease Higher risk is associated with: - age under 2–3 months, especially under 6 weeks; - prematurity; - chronic lung disease of prematurity; - hemodynamically important congenital heart disease; - neuromuscular disease impairing ventilation or secretion clearance; - important airway abnormalities; - immunocompromise; - major medical complexity; - apnea during the current illness; - poor baseline growth; - tobacco-smoke exposure; - social circumstances that make observation or rapid return difficult.[1-3] These factors lower the threshold for observation or admission but do not by themselves determine respiratory-support level. ## Clinical assessment ### Respiratory status Assess and trend: - respiratory rate; - subcostal, intercostal, and suprasternal recession; - nasal flaring or grunting; - air entry; - crackles and wheeze; - apnea; - color and perfusion; - pulse oximetry; - interaction, tone, and fatigue. Severe distress, recurrent apnea, cyanosis, or exhaustion warrants emergency escalation. ### Feeding and hydration Ask about usual intake and current intake, number of wet diapers, vomiting, and ability to coordinate suck-swallow-breathe. Look for dry mucosa, prolonged capillary refill, reduced urine output, lethargy, and weight loss when available. An infant who cannot safely maintain hydration because of tachypnea or fatigue may require nasogastric or IV support even if oxygenation is acceptable. ## Differential diagnosis | Alternative | Clues | Action | |---|---|---| | Pneumonia | High fever, focal crackles, focal reduced breath sounds, toxic appearance | Targeted imaging/antibiotic pathway when clinically indicated | | Asthma/viral-induced wheeze | Older child, recurrent episodic wheeze, atopy, prior bronchodilator response | Reconsider diagnosis rather than repeated empiric bronchodilators in a typical infant | | Heart failure | Poor growth, sweating with feeds, hepatomegaly, murmur | Cardiac evaluation | | Foreign-body aspiration | Sudden onset, focal or unilateral findings | Airway imaging/bronchoscopy pathway | | Pertussis | Paroxysmal cough, apnea, exposure | PCR and treatment/isolation pathway | | Sepsis | Ill appearance, poor perfusion, temperature instability | Age-appropriate sepsis evaluation | | Metabolic acidosis | Deep breathing without typical lower-airway findings | Blood gas/metabolic testing | ## Investigations ### Pulse oximetry Measure oxygen saturation in infants referred to hospital or when severity is uncertain. Ensure a good waveform and interpret values in context. Brief desaturations during sleep are common; decisions should be based on **persistent** hypoxemia and the child's overall status.[1] ### Chest radiography Do not order chest radiography routinely in typical bronchiolitis. Consider it when: - the diagnosis is unclear; - focal bacterial pneumonia is strongly suspected; - there is severe or unusual deterioration; - pneumothorax or another complication is possible; - the child requires intensive respiratory support and imaging will change management.[1,2] ### Blood tests and blood gas Routine CBC, CRP, electrolytes, and blood gas are unnecessary in uncomplicated disease. Obtain targeted studies when severe dehydration, sepsis, electrolyte disturbance, impending respiratory failure, or another diagnosis is plausible. Blood gas testing is most useful in a tiring infant with severe disease or escalating respiratory support. Rising carbon dioxide with acidemia in the context of worsening clinical status supports ventilatory failure. ### Viral testing Do not test routinely when the result will not alter care. Test selectively for cohorting, influenza treatment, outbreak control, or immunocompromised-host management. ## Acute management ### 1. Minimize distress Agitation increases oxygen consumption and work of breathing. Cluster care, use caregiver holding when safe, and avoid repeated low-value procedures. ### 2. Nasal secretion management Gentle superficial nasal suction can improve feeding or breathing when secretions obstruct the nares. Deep routine suction is uncomfortable and may cause mucosal trauma; reserve more intensive airway clearance for a clear clinical need.[1-3] ### 3. Oxygen For most children aged **≥6 weeks**, start supplemental oxygen for persistent **SpO₂ <90%**. For infants **<6 weeks** or children with clinically important underlying conditions, NICE uses **<92%**.[1] Use the lowest level of support that maintains the jurisdictional target while the child remains clinically stable. Avoid chasing transient dips with unnecessary oxygen escalation. ### 4. Fluids and feeding Continue oral or breastfeeding if the infant can feed safely. Use smaller, more frequent feeds where helpful. If oral intake is unsafe or inadequate: - **nasogastric/orogastric feeding** is appropriate for many infants with moderate disease; - **IV isotonic fluid** is appropriate when enteral feeding is unsafe, poorly tolerated, or contraindicated. Avoid overhydration because inappropriate antidiuretic hormone secretion and positive fluid balance can worsen respiratory status. Monitor electrolytes when IV fluids are ongoing or the child is severely ill.[1,2] ## Therapies not routinely recommended | Therapy | Routine role | Reason | |---|---|---| | Salbutamol/albuterol | No | No consistent meaningful benefit in typical bronchiolitis | | Nebulized epinephrine | No | No routine sustained benefit | | Systemic/inhaled corticosteroid | No | Does not improve routine outcomes | | Hypertonic saline | No routine acute-care role | Benefit is inconsistent and small | | Antibiotic | No unless bacterial infection is suspected/confirmed | Bronchiolitis is viral | | Ipratropium | No | No established benefit | | Montelukast | No | No established benefit | | Chest physiotherapy | No | Does not improve routine outcomes and increases handling | A single bronchodilator “trial” should not be used reflexively in young infants with a classic first episode. If the child is older with recurrent wheeze and an atopic phenotype, reconsider whether the syndrome is bronchiolitis or asthma/viral-induced wheeze.[1-3] ## High-flow nasal cannula HFNC delivers warmed, humidified gas at flows exceeding conventional nasal-cannula delivery. A 2024 Cochrane review found that, compared with low-flow oxygen, HFNC may modestly reduce duration of oxygen and hospital stay and reduces treatment escalation, without a clear increase in adverse events; certainty for several outcomes remains limited.[4] The 2025 Australasian guideline recommends **against first-line HFNC in moderate bronchiolitis**. Use low-flow oxygen first and escalate to HFNC when hypoxemia persists or respiratory distress remains clinically important despite conventional support.[3] ### Reassessing HFNC Within the first hour after initiation, reassess: - respiratory rate and effort; - heart rate; - oxygen requirement; - air entry; - apnea; - mental status and fatigue. Failure to improve or worsening distress should trigger escalation to pediatric critical care rather than simply increasing flow indefinitely. ## CPAP and invasive ventilation CPAP or other noninvasive positive-pressure support can be used in severe bronchiolitis when HFNC is inadequate, particularly in a monitored pediatric critical-care setting. Evidence does not establish universal superiority of HFNC or CPAP across all severe phenotypes; local expertise matters.[3,4] ### Indications for urgent critical-care escalation - recurrent or prolonged apnea; - exhaustion or falling respiratory effort; - worsening hypoxemia despite escalating noninvasive support; - rising carbon dioxide with acidemia and clinical deterioration; - reduced consciousness; - severe air-entry reduction; - shock or hemodynamic instability.[1-3] Intubation is a clinical decision. Do not wait for a fixed carbon-dioxide threshold in a deteriorating infant. ## Admission Admit or observe when there is: - apnea; - persistent oxygen need; - severe or worsening work of breathing; - inability to maintain hydration safely; - very young age with concerning trajectory; - important cardiopulmonary, neuromuscular, or immune comorbidity; - unreliable home observation or inability to return promptly.[1] A saturation value at or just above a threshold does not make discharge safe when feeding, work of breathing, apnea risk, or social safety is poor. ## Discharge criteria Before discharge, confirm: - clinically stable or improving respiratory effort; - no recent clinically important apnea; - adequate hydration with a workable feeding plan; - stable oxygen saturation in room air for an appropriate observation period, including sleep when relevant; - caregivers can recognize deterioration and clear nasal secretions; - reliable access to follow-up and urgent reassessment.[1] NICE uses sustained room-air **SpO₂ ≥90% for children aged ≥6 weeks** and **≥92% for infants <6 weeks or children with underlying health conditions** as part of discharge criteria.[1] ## Fever and bacterial coinfection Bacterial coinfection is uncommon in typical bronchiolitis, but the risk is not zero. A markedly ill infant, focal bacterial findings, persistent high fever, or age-specific sepsis risk warrants targeted investigation. Very young febrile infants should be managed using an age-appropriate febrile-infant pathway rather than assuming the viral diagnosis excludes invasive bacterial infection. ## Apnea Apnea can be the presenting manifestation of RSV or other bronchiolitis, particularly in young or preterm infants. Recurrent apnea requires admission and continuous monitoring. Evaluate for sepsis, pertussis, seizure, metabolic disease, and other causes when the pattern is atypical. ## RSV prevention RSV prevention is separate from treatment of an acute episode. Current AAP 2026 guidance recommends long-acting RSV monoclonal-antibody immunization for:[5] - infants younger than **8 months** born during or entering their first RSV season unless adequately protected through maternal RSV vaccination; - selected high-risk children aged **8–19 months** entering their second RSV season. Eligibility details vary by jurisdiction and change with product availability and public-health policy. Use current national guidance for exact timing and product selection. In US guidance, when maternal RSV vaccination was given during the current pregnancy at least 14 days before birth, most infants do not also require monoclonal-antibody immunization; exceptions can apply when maternal antibody transfer or protection is likely inadequate.[5] > **Current practice:** Preventive monoclonal antibodies reduce RSV disease risk but are not antivirals and do not treat established bronchiolitis. ## Complications Potential complications include: - dehydration; - apnea; - acute hypoxemic or hypercapnic respiratory failure; - atelectasis; - secondary bacterial infection, uncommon but important when present; - pneumothorax, rare and more associated with positive-pressure support; - feeding-associated aspiration in exhausted infants. ## Acute management checklist ```text Typical bronchiolitis? | +-- Assess apnea, work of breathing, SpO2, hydration, age/comorbidity | +-- Mild, feeding well, no persistent hypoxemia | -> supportive care + safety-net discharge | +-- Persistent hypoxemia | -> low-flow oxygen | -> reassess | +-- improving -> continue supportive care | +-- persistent hypoxemia/distress -> HFNC per protocol | +-- Apnea, fatigue, worsening gas exchange, altered responsiveness -> urgent pediatric critical-care escalation -> CPAP/noninvasive support or intubation as clinically required ``` ## References 1. National Institute for Health and Care Excellence. *Bronchiolitis in children: diagnosis and management (NG9).* Published 2015; updated August 9, 2021. https://www.nice.org.uk/guidance/ng9 2. Ralston SL, Lieberthal AS, Meissner HC, et al. Clinical practice guideline: the diagnosis, management, and prevention of bronchiolitis. *Pediatrics*. 2014;134(5):e1474-e1502. doi:10.1542/peds.2014-2742. PMID:25349312. https://pubmed.ncbi.nlm.nih.gov/25349312/ 3. Borland ML, et al. Australasian Bronchiolitis PREDICT Guideline 2025: evidence-based recommendations for care across diverse settings. *J Paediatr Child Health*. 2025. doi:10.1111/jpc.70142. https://onlinelibrary.wiley.com/doi/10.1111/jpc.70142 4. Armarego M, Forde H, Wills K, Beggs SA. High-flow nasal cannula therapy for infants with bronchiolitis. *Cochrane Database Syst Rev*. 2024;3:CD009609. doi:10.1002/14651858.CD009609.pub3. PMID:38506440. https://pubmed.ncbi.nlm.nih.gov/38506440/ 5. American Academy of Pediatrics. Recommendations for the Prevention of Respiratory Syncytial Virus Disease in Infants and Children: Policy Statement. *Pediatrics*. 2026. doi:10.1542/peds.2026-079047. https://publications.aap.org/pediatrics/article/doi/10.1542/peds.2026-079047/208784/19:T476a,## Summary Acute bronchiolitis is a clinical syndrome of viral lower-respiratory-tract infection in infants and young children, most commonly during the first year of life. A typical illness begins with coryza and cough, followed by tachypnea, increased work of breathing, wheeze and/or crackles, reduced feeding, and sometimes hypoxemia or apnea.[1-3] Diagnosis is usually clinical. **Routine chest radiography, blood tests, and viral testing are not indicated in an otherwise typical case.** Nonspecific atelectatic or interstitial changes on chest radiography can be misinterpreted as bacterial pneumonia and drive unnecessary antibiotic use.[1,2] Treatment is predominantly supportive: minimize distress, clear nasal secretions when obstruction interferes with breathing or feeding, maintain hydration and nutrition, provide oxygen for persistent hypoxemia, and escalate respiratory support when the child is tiring or failing lower-level support.[1-4] For most infants aged **6 weeks or older**, NICE and the 2025 Australasian guideline use persistent room-air **SpO₂ <90%** as the threshold for supplemental oxygen in hospital. A higher threshold of **<92%** is used for infants younger than 6 weeks and for children with important underlying conditions in NICE guidance.[1,3] Clinical trajectory, apnea, feeding, work of breathing, age, and comorbidity remain essential; a single saturation reading should not determine admission or discharge. Do **not** routinely use salbutamol/albuterol, nebulized epinephrine, systemic or inhaled corticosteroids, hypertonic saline, ipratropium, montelukast, antibiotics without a bacterial indication, or chest physiotherapy for typical bronchiolitis.[1-3] The updated Australasian guidance reserves a possible corticosteroid-plus-epinephrine strategy for selected critically ill infants under specialist intensive-care protocols; this should not be extrapolated to routine ward or emergency care.[3] High-flow nasal cannula (HFNC) can reduce escalation from conventional oxygen in hospitalized infants, but contemporary guidance does **not** support routine first-line HFNC for moderate bronchiolitis. Start with low-flow oxygen when oxygen is needed; use HFNC when persistent hypoxemia or respiratory distress remains despite appropriate conventional support, according to local pediatric respiratory protocols.[3,4] Impending respiratory failure is suggested by recurrent apnea, exhaustion or decreasing respiratory effort, altered responsiveness, poor air entry, persistent/worsening hypoxemia despite support, rising carbon dioxide with acidemia, or hemodynamic instability. These findings require urgent senior pediatric/critical-care review.[1-3] RSV prevention has changed substantially. Current 2026 American Academy of Pediatrics (AAP) policy recommends seasonal long-acting RSV monoclonal-antibody immunization for eligible infants younger than 8 months who are not adequately protected by maternal RSV vaccination, and for selected high-risk children aged 8–19 months entering a second RSV season.[5] Prevention does not treat established bronchiolitis. > **Clinical pearl:** The sickest infant may become quieter rather than more visibly distressed. Falling respiratory effort with persistent tachycardia, hypoxemia, poor air entry, or altered responsiveness suggests fatigue, not recovery. ## Definition and typical course Bronchiolitis is an acute viral small-airway illness in a baby or young child, usually younger than 2 years, with an upper-respiratory prodrome followed by lower-airway findings and no better alternative diagnosis. Definitions differ by jurisdiction; the disease is most typical in infants.[1,2] A common trajectory is: 1. rhinorrhea and nasal congestion; 2. cough and reduced feeding; 3. tachypnea with subcostal/intercostal recession; 4. diffuse crackles and/or wheeze; 5. variable hypoxemia and feeding intolerance. Symptoms often peak around days 3–5, but management should follow the individual child's physiology rather than a calendar rule.[1] ## Etiology Respiratory syncytial virus (RSV) is the leading cause of severe infant bronchiolitis. Other causes include rhinovirus, human metapneumovirus, influenza, parainfluenza, adenovirus, seasonal coronaviruses, and SARS-CoV-2. Coinfection can occur. Identifying the virus usually does not change treatment. Viral testing may be useful when it changes cohorting, infection-control practice, influenza antiviral treatment, or management of an immunocompromised child. ## Pathophysiology Viral infection injures ciliated airway epithelium and produces mucosal edema, mucus, and cellular debris. Because infant bronchioles are narrow, modest swelling markedly increases resistance. Partial obstruction produces air trapping; complete obstruction causes distal atelectasis. Ventilation-perfusion mismatch produces hypoxemia while tachypnea and nasal obstruction impair feeding.[2] Young infants are vulnerable because of: - small airway caliber; - compliant chest wall; - limited respiratory reserve; - dependence on nasal breathing; - immature respiratory control and apnea risk; - limited ability to compensate for reduced intake. ## Risk factors for severe disease Higher risk is associated with: - age under 2–3 months, especially under 6 weeks; - prematurity; - chronic lung disease of prematurity; - hemodynamically important congenital heart disease; - neuromuscular disease impairing ventilation or secretion clearance; - important airway abnormalities; - immunocompromise; - major medical complexity; - apnea during the current illness; - poor baseline growth; - tobacco-smoke exposure; - social circumstances that make observation or rapid return difficult.[1-3] These factors lower the threshold for observation or admission but do not by themselves determine respiratory-support level. ## Clinical assessment ### Respiratory status Assess and trend: - respiratory rate; - subcostal, intercostal, and suprasternal recession; - nasal flaring or grunting; - air entry; - crackles and wheeze; - apnea; - color and perfusion; - pulse oximetry; - interaction, tone, and fatigue. Severe distress, recurrent apnea, cyanosis, or exhaustion warrants emergency escalation. ### Feeding and hydration Ask about usual intake and current intake, number of wet diapers, vomiting, and ability to coordinate suck-swallow-breathe. Look for dry mucosa, prolonged capillary refill, reduced urine output, lethargy, and weight loss when available. An infant who cannot safely maintain hydration because of tachypnea or fatigue may require nasogastric or IV support even if oxygenation is acceptable. ## Differential diagnosis | Alternative | Clues | Action | |---|---|---| | Pneumonia | High fever, focal crackles, focal reduced breath sounds, toxic appearance | Targeted imaging/antibiotic pathway when clinically indicated | | Asthma/viral-induced wheeze | Older child, recurrent episodic wheeze, atopy, prior bronchodilator response | Reconsider diagnosis rather than repeated empiric bronchodilators in a typical infant | | Heart failure | Poor growth, sweating with feeds, hepatomegaly, murmur | Cardiac evaluation | | Foreign-body aspiration | Sudden onset, focal or unilateral findings | Airway imaging/bronchoscopy pathway | | Pertussis | Paroxysmal cough, apnea, exposure | PCR and treatment/isolation pathway | | Sepsis | Ill appearance, poor perfusion, temperature instability | Age-appropriate sepsis evaluation | | Metabolic acidosis | Deep breathing without typical lower-airway findings | Blood gas/metabolic testing | ## Investigations ### Pulse oximetry Measure oxygen saturation in infants referred to hospital or when severity is uncertain. Ensure a good waveform and interpret values in context. Brief desaturations during sleep are common; decisions should be based on **persistent** hypoxemia and the child's overall status.[1] ### Chest radiography Do not order chest radiography routinely in typical bronchiolitis. Consider it when: - the diagnosis is unclear; - focal bacterial pneumonia is strongly suspected; - there is severe or unusual deterioration; - pneumothorax or another complication is possible; - the child requires intensive respiratory support and imaging will change management.[1,2] ### Blood tests and blood gas Routine CBC, CRP, electrolytes, and blood gas are unnecessary in uncomplicated disease. Obtain targeted studies when severe dehydration, sepsis, electrolyte disturbance, impending respiratory failure, or another diagnosis is plausible. Blood gas testing is most useful in a tiring infant with severe disease or escalating respiratory support. Rising carbon dioxide with acidemia in the context of worsening clinical status supports ventilatory failure. ### Viral testing Do not test routinely when the result will not alter care. Test selectively for cohorting, influenza treatment, outbreak control, or immunocompromised-host management. ## Acute management ### 1. Minimize distress Agitation increases oxygen consumption and work of breathing. Cluster care, use caregiver holding when safe, and avoid repeated low-value procedures. ### 2. Nasal secretion management Gentle superficial nasal suction can improve feeding or breathing when secretions obstruct the nares. Deep routine suction is uncomfortable and may cause mucosal trauma; reserve more intensive airway clearance for a clear clinical need.[1-3] ### 3. Oxygen For most children aged **≥6 weeks**, start supplemental oxygen for persistent **SpO₂ <90%**. For infants **<6 weeks** or children with clinically important underlying conditions, NICE uses **<92%**.[1] Use the lowest level of support that maintains the jurisdictional target while the child remains clinically stable. Avoid chasing transient dips with unnecessary oxygen escalation. ### 4. Fluids and feeding Continue oral or breastfeeding if the infant can feed safely. Use smaller, more frequent feeds where helpful. If oral intake is unsafe or inadequate: - **nasogastric/orogastric feeding** is appropriate for many infants with moderate disease; - **IV isotonic fluid** is appropriate when enteral feeding is unsafe, poorly tolerated, or contraindicated. Avoid overhydration because inappropriate antidiuretic hormone secretion and positive fluid balance can worsen respiratory status. Monitor electrolytes when IV fluids are ongoing or the child is severely ill.[1,2] ## Therapies not routinely recommended | Therapy | Routine role | Reason | |---|---|---| | Salbutamol/albuterol | No | No consistent meaningful benefit in typical bronchiolitis | | Nebulized epinephrine | No | No routine sustained benefit | | Systemic/inhaled corticosteroid | No | Does not improve routine outcomes | | Hypertonic saline | No routine acute-care role | Benefit is inconsistent and small | | Antibiotic | No unless bacterial infection is suspected/confirmed | Bronchiolitis is viral | | Ipratropium | No | No established benefit | | Montelukast | No | No established benefit | | Chest physiotherapy | No | Does not improve routine outcomes and increases handling | A single bronchodilator “trial” should not be used reflexively in young infants with a classic first episode. If the child is older with recurrent wheeze and an atopic phenotype, reconsider whether the syndrome is bronchiolitis or asthma/viral-induced wheeze.[1-3] ## High-flow nasal cannula HFNC delivers warmed, humidified gas at flows exceeding conventional nasal-cannula delivery. A 2024 Cochrane review found that, compared with low-flow oxygen, HFNC may modestly reduce duration of oxygen and hospital stay and reduces treatment escalation, without a clear increase in adverse events; certainty for several outcomes remains limited.[4] The 2025 Australasian guideline recommends **against first-line HFNC in moderate bronchiolitis**. Use low-flow oxygen first and escalate to HFNC when hypoxemia persists or respiratory distress remains clinically important despite conventional support.[3] ### Reassessing HFNC Within the first hour after initiation, reassess: - respiratory rate and effort; - heart rate; - oxygen requirement; - air entry; - apnea; - mental status and fatigue. Failure to improve or worsening distress should trigger escalation to pediatric critical care rather than simply increasing flow indefinitely. ## CPAP and invasive ventilation CPAP or other noninvasive positive-pressure support can be used in severe bronchiolitis when HFNC is inadequate, particularly in a monitored pediatric critical-care setting. Evidence does not establish universal superiority of HFNC or CPAP across all severe phenotypes; local expertise matters.[3,4] ### Indications for urgent critical-care escalation - recurrent or prolonged apnea; - exhaustion or falling respiratory effort; - worsening hypoxemia despite escalating noninvasive support; - rising carbon dioxide with acidemia and clinical deterioration; - reduced consciousness; - severe air-entry reduction; - shock or hemodynamic instability.[1-3] Intubation is a clinical decision. Do not wait for a fixed carbon-dioxide threshold in a deteriorating infant. ## Admission Admit or observe when there is: - apnea; - persistent oxygen need; - severe or worsening work of breathing; - inability to maintain hydration safely; - very young age with concerning trajectory; - important cardiopulmonary, neuromuscular, or immune comorbidity; - unreliable home observation or inability to return promptly.[1] A saturation value at or just above a threshold does not make discharge safe when feeding, work of breathing, apnea risk, or social safety is poor. ## Discharge criteria Before discharge, confirm: - clinically stable or improving respiratory effort; - no recent clinically important apnea; - adequate hydration with a workable feeding plan; - stable oxygen saturation in room air for an appropriate observation period, including sleep when relevant; - caregivers can recognize deterioration and clear nasal secretions; - reliable access to follow-up and urgent reassessment.[1] NICE uses sustained room-air **SpO₂ ≥90% for children aged ≥6 weeks** and **≥92% for infants <6 weeks or children with underlying health conditions** as part of discharge criteria.[1] ## Fever and bacterial coinfection Bacterial coinfection is uncommon in typical bronchiolitis, but the risk is not zero. A markedly ill infant, focal bacterial findings, persistent high fever, or age-specific sepsis risk warrants targeted investigation. Very young febrile infants should be managed using an age-appropriate febrile-infant pathway rather than assuming the viral diagnosis excludes invasive bacterial infection. ## Apnea Apnea can be the presenting manifestation of RSV or other bronchiolitis, particularly in young or preterm infants. Recurrent apnea requires admission and continuous monitoring. Evaluate for sepsis, pertussis, seizure, metabolic disease, and other causes when the pattern is atypical. ## RSV prevention RSV prevention is separate from treatment of an acute episode. Current AAP 2026 guidance recommends long-acting RSV monoclonal-antibody immunization for:[5] - infants younger than **8 months** born during or entering their first RSV season unless adequately protected through maternal RSV vaccination; - selected high-risk children aged **8–19 months** entering their second RSV season. Eligibility details vary by jurisdiction and change with product availability and public-health policy. Use current national guidance for exact timing and product selection. In US guidance, when maternal RSV vaccination was given during the current pregnancy at least 14 days before birth, most infants do not also require monoclonal-antibody immunization; exceptions can apply when maternal antibody transfer or protection is likely inadequate.[5] > **Current practice:** Preventive monoclonal antibodies reduce RSV disease risk but are not antivirals and do not treat established bronchiolitis. ## Complications Potential complications include: - dehydration; - apnea; - acute hypoxemic or hypercapnic respiratory failure; - atelectasis; - secondary bacterial infection, uncommon but important when present; - pneumothorax, rare and more associated with positive-pressure support; - feeding-associated aspiration in exhausted infants. ## Acute management checklist ```text Typical bronchiolitis? | +-- Assess apnea, work of breathing, SpO2, hydration, age/comorbidity | +-- Mild, feeding well, no persistent hypoxemia | -> supportive care + safety-net discharge | +-- Persistent hypoxemia | -> low-flow oxygen | -> reassess | +-- improving -> continue supportive care | +-- persistent hypoxemia/distress -> HFNC per protocol | +-- Apnea, fatigue, worsening gas exchange, altered responsiveness -> urgent pediatric critical-care escalation -> CPAP/noninvasive support or intubation as clinically required ``` ## References 1. National Institute for Health and Care Excellence. *Bronchiolitis in children: diagnosis and management (NG9).* Published 2015; updated August 9, 2021. https://www.nice.org.uk/guidance/ng9 2. Ralston SL, Lieberthal AS, Meissner HC, et al. Clinical practice guideline: the diagnosis, management, and prevention of bronchiolitis. *Pediatrics*. 2014;134(5):e1474-e1502. doi:10.1542/peds.2014-2742. PMID:25349312. https://pubmed.ncbi.nlm.nih.gov/25349312/ 3. Borland ML, et al. Australasian Bronchiolitis PREDICT Guideline 2025: evidence-based recommendations for care across diverse settings. *J Paediatr Child Health*. 2025. doi:10.1111/jpc.70142. https://onlinelibrary.wiley.com/doi/10.1111/jpc.70142 4. Armarego M, Forde H, Wills K, Beggs SA. High-flow nasal cannula therapy for infants with bronchiolitis. *Cochrane Database Syst Rev*. 2024;3:CD009609. doi:10.1002/14651858.CD009609.pub3. PMID:38506440. https://pubmed.ncbi.nlm.nih.gov/38506440/ 5. American Academy of Pediatrics. Recommendations for the Prevention of Respiratory Syncytial Virus Disease in Infants and Children: Policy Statement. *Pediatrics*. 2026. doi:10.1542/peds.2026-079047. https://publications.aap.org/pediatrics/article/doi/10.1542/peds.2026-079047/208784/7:["$","$L17",null,{"article":{"id":"medical-acute-bronchiolitis","title":"Acute Bronchiolitis","slug":"acute-bronchiolitis","description":"Acute bronchiolitis is a clinical syndrome of viral lower-respiratory-tract infection in infants and young children, most commonly during the first year of life. 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