Respiratory rate and severity of illness in babies under 6 months old.

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.