Bronchiolitis Severity Bands
Classify bronchiolitis as mild, moderate, or severe using age-based respiratory rate plus key exam findings.
Last reviewed: February 26, 2026
Clinical disclaimer
Bands: 2-12 months <50 / 51-70 / >70; 12-24 months <40 / 41-60 / >60.
How the banding tool works
The severity band is determined by the highest category in any domain. For example, severe work of breathing results in a severe band even if other findings are mild.
- Age-based respiratory rate thresholds for infants 2-12 months and 12-24 months.
- Work of breathing categories based on retractions and severe effort signs.
- Oxygen requirement and mental status add additional severity cues.
Respiratory rate bands
- Age 2-12 months: mild <50, moderate 51-70, severe >70.
- Age 12-24 months: mild <40, moderate 41-60, severe >60.
Use a calm resting rate; crying elevates rate and can overestimate severity.
Work of breathing and oxygen
- Work of breathing: none (mild), intercostal/subcostal retractions (moderate), nasal flaring, grunting, head bobbing, or suprasternal retractions (severe).
- Oxygen requirement: none (mild), <1.5 L/min (moderate), >1.5 L/min (severe).
- Mental status: normal (mild), agitated (moderate), lethargic or inconsolable (severe).
Interpreting severity bands
- Mild: supportive care with close follow-up if feeding and oxygenation are adequate.
- Moderate: consider observation or admission based on hydration, oxygenation, and risk factors.
- Severe: high risk for deterioration; escalate monitoring and respiratory support per local pathway.
Reassessment cadence
- After suctioning, oxygen adjustment, or hydration intervention: repeat banding in the same care block.
- If mild/moderate and stable: continue interval reassessment per local bronchiolitis protocol.
- If worsening work of breathing, feeding tolerance, or mentation: immediate re-banding and escalation.
Shift handoff checklist
- Highest-severity domain driving current band classification.
- Recent interventions and observed response trajectory.
- Current oxygen and feeding/hydration status.
- Next reassessment interval and escalation threshold.
Related calculators
References
Frequently asked questions
This tool is based on a consensus-modified respiratory assessment used in clinical pathways. It is not a formally validated score and should be used to support, not replace, clinical judgment.
The overall severity is the highest category from any domain (respiratory rate, work of breathing, oxygen requirement, or mental status).
The referenced pathway applies to infants 2-24 months old. Outside this range, use local guidance.
No. It is a simpler banding tool. Wang and RDAI are formal scoring systems that can be used to trend severity over time.
Document which domain set the band, trend over time, and intervention timing. A consistent domain-level record improves handoff safety and escalation timing.