Acute bronchiolitis is caused by a viral infection, usually affecting children younger than two years of age.

[1] Occasionally, hospital admission for oxygen, particularly high flow nasal cannula, or intravenous fluids is needed in more severe cases of disease.

After the acute illness, it is common for the airways to remain sensitive for several weeks, leading to recurrent cough and wheeze.

Other agents that cause this illness include, but are not limited to, human metapneumovirus, influenza, parainfluenza, coronavirus, adenovirus, rhinovirus and mycoplasma.

[9][20] Bronchiolitis may be differentiated from some of these by the characteristic pattern of preceding febrile upper respiratory tract symptoms lasting for 1 to 3 days with associated persistent cough, increased work of breathing, and wheezing.

[9] The US Food and Drug Administration (FDA) has currently approved two RSV vaccines for adults ages 60 and older, Arexvy (GSK plc) and Abrysvo (Pfizer).

"[23] It is unclear how effective these vaccines will be in preventing infection with bronchiolitis since they are new, although the FDA has approved them due to the clear benefit that they have shown in clinical trials.

[9] Otherwise healthy premature infants that were born after a gestational age of 29 weeks should not be administered Palivizumab, as the harms outweigh the benefits.

[9] Tobacco smoke exposure has been shown to increase both the rates of lower respiratory disease in infants, as well as the risk and severity of bronchiolitis.

[9] Guidelines recommend that parents be fully educated on the risks of tobacco smoke exposure on children with bronchiolitis.

[8] Most guidelines recommend sufficient fluids and nutritional support for affected children along with frequent nasal suctioning.

[9] Accuracy of pulse oximetry is limited in the 76% to 90% range and there is weak correlation between oxygen saturation and respiratory distress as brief hypoxemia is common in healthy infants.

[9] Infants are nose breathers and bronchiolitis causes congestion of the airways with secretions that can make it difficult to feed and breathe.

Clinical guidelines state that routine suctioning is safe and can provide relief for infants which allows them to eat and sleep more comfortably.

[9] The use of humidified, heated, high-flow nasal cannula may be a safe initial therapy to decrease work of breathing and need for intubation.

[20][40] The use of CPAP has very limited evidence for improving breathing (a decreased respiratory rate) and does not reduce the need for mechanical ventilation.

[9][15] Nebulized hypertonic saline (3%) has limited evidence of benefit and previous studies lack consistency and standardization.

[9][20][46][47] Additionally, there are adverse effects to the use of bronchodilators in children such as tachycardia and tremors, as well as adding increased cost to the medical visit.

[48][46] Several studies have shown that bronchodilation with β-adrenergic agents such as salbutamol may improve symptoms briefly but do not affect the overall course of the illness or reduce the need for hospitalization.

[20][49][50] The current state of evidence suggests that nebulized epinephrine is not indicated for children with bronchiolitis except as a trial of rescue therapy for severe cases.

[9][20] Epinephrine is an α and β adrenergic agonist that is used to treat other upper respiratory tract illnesses, such as croup, as a nebulized solution.

[15] It is the leading cause of hospital admission for respiratory disease among infants in the United States and accounts for one out of every 13 primary care visits.

[17] During the pandemic, there was a sharp decrease in cases of bronchiolitis and other respiratory illness, which is likely due to social distancing and other precautions.

[17] After social distancing and other precautions were lifted, there was increases in the cases of RSV and bronchiolitis worldwide to varying degrees.

Recent evidence suggests that bronchiolitis still poses a large disease burden to both primary care providers and emergency departments.