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Respiratory rate and severity of illness in babies under 6 months old
C J Morley1, A J Thornton, M A Fowler
1Department of Paediatrics, University of Cambridge.
Insights
This study establishes normal respiratory rates for infants under six months. Awake infants averaged 61 breaths/minute, while sleeping infants breathed slower, unaffected by illness severity.
Area of Science:
- Pediatrics
- Respiratory Physiology
Background:
- Establishing normal respiratory rates is crucial for infant health assessment.
- Variations in infant respiratory rate can indicate underlying health issues.
Purpose of the Study:
- To define the normal range of respiratory rate in infants under six months of age.
- To investigate the correlation between respiratory rate and infant state (awake, asleep, crying), illness severity, and diagnosis.
Main Methods:
- Respiratory rate was measured by two observers in 1007 infants (<6 months).
- Infants were assessed either during hospital visits for acute illness (709) or randomly at home (298).
- Infant state (asleep, content, crying), illness severity, and diagnosis were recorded.
Main Results:
- The mean respiratory rate for awake infants was 61 breaths/minute (SD 18 at hospital, SD 14 at home).
- Awake respiratory rate did not correlate with illness severity or lower respiratory tract infections.
- Sleeping infants had a significantly lower mean rate (42 breaths/minute, SD 12).
- Crying infants had a lower mean rate (51 breaths/minute, SD 14) than awake/content infants.
Conclusions:
- Normal respiratory rate ranges for infants under six months have been defined.
- Infant state significantly influences respiratory rate, with sleeping and crying infants exhibiting lower rates than awake infants.
- Respiratory rate in awake infants is not a reliable indicator of illness severity or serious lower respiratory tract infections.
Abstract:
This paper defines the normal range of respiratory rate in babies under 6 months of age. It was counted by two observers in 1007 babies of whom 709 were seen when presenting to hospital for assessment of an acute illness, and 298 on a random basis at home. Whether they were asleep, content, or crying was recorded and the severity of their illness graded. The diagnosis was also recorded. The mean (SD) for the respiratory rate in babies seen awake was 61 (18) breaths/minute at hospital and 61 (14) breaths/minute at home. The respiratory rate when awake did not correlate with the severity of a baby's illness or the presence of serious lower respiratory tract infections. Sleeping babies had a significantly lower mean rate than awake babies at 42 (12) breaths/minute. Crying babies had a significantly lower mean rate than awake and content babies: 51 (14) breaths/minute compared with 61 (18) breaths/minute.