The investigators will conduct a study around the best way to monitor infants hospitalized with bronchiolitis, the most common lung infection and a leading reason for hospitalization in infants. Infants with bronchiolitis have breathing difficulties and are provided supplemental oxygen if their oxygen levels are low. However, there is uncertainty regarding how to best monitor oxygen levels. A probe placed on the hand or foot can be used to monitor oxygen levels all the time (continuous oxygen monitoring) or just every 4-6 hours (intermittent oxygen monitoring). Research has suggested that placing infants with bronchiolitis on continuous monitoring results in unnecessary use of oxygen and infants staying longer in hospital. However, due to the lack of high quality research, its unclear which strategy is best and practice varies. The objective of this study is to conduct high quality research across hospitals to determine whether intermittent compared to continuous oxygen monitoring will reduce the length of hospital stay in infants hospitalized with bronchiolitis. The investigators will also compare safety and cost. The results of this study will inform bronchiolitis practice standards and the best use of health care resources.

BACKGROUND This research protocol focuses on bronchiolitis, a leading cause of infant hospitalization and cumulative expense for the health care system. Supportive management, such as oxygen supplementation and monitoring, is the major focus of care, as active medical treatment is not effective. Oxygen saturation monitoring may be performed on an intermittent (e.g. every 4-6hrs) or continuous basis for stable infants hospitalized with bronchiolitis. Observational studies find that the use of continuous monitoring is associated with overuse of supplemental oxygen and longer hospital stay. Based on this low quality evidence, practice guidelines state that clinicians may choose not to use continuous monitoring and practice variation exists due to a lack of RCTs.

SPECIFIC AIMS Primary: To determine if intermittent vs continuous oxygen saturation monitoring will reduce length of hospital stay in infants with bronchiolitis. Secondary: To determine differences in other outcomes - effectiveness, safety, acceptability, and cost.

METHODOLOGY Design: multi-centre, pragmatic, parallel group, 1:1, two arm superiority RCT. Population: Previously healthy infants (4 weeks-2 years) hospitalized with bronchiolitis who are clinically stable, will be recruited from children's and community hospitals in Ontario, Canada.

Interventions: Randomization to intermittent (every 4hrs) or continuous oxygen saturation monitoring. In keeping with local and national clinical practice guidelines, an acceptable oxygen saturation target of ≥ 90% will be used for both groups.

Children admitted to the general pediatric inpatient unit (GPIU) with bronchiolitis will be eligible if their clinical status is stable and not at high risk of deterioration

Inclusion Criteria:

• Clinical diagnosis of bronchiolitis as determined by the attending physician.
• First episode of acute bronchiolitis.
• Age: 4 weeks to 24 months.
• Clinical status stable for 6 hours
• Parent consent

Exclusion Criteria:

• Known risk factors for clinical deterioration including chronic medical condition; premature birth (<35weeks), history of apnea, weight < 4kg, receiving morphine
• Patient on heated high flow oxygen at enrolment
• ICU admission on current admission
• No telephone available