TUESDAY, March 15 (HealthDay News) -- Centile charts derived from a systematic review of observational studies provide new evidence-based reference ranges for these vital signs but do not agree with existing reference ranges for heart rate and respiratory rate in children; the research has been published online March 15 in The Lancet.
Susannah Fleming, Ph.D., from Oxford University in the United Kingdom, and colleagues analyzed data from 69 studies to derive new centile charts for heart rate and respiratory rate for children from birth to 18 years of age. Heart rates from 143,346 children and respiratory rates from 3,881 children were used to create centile charts in relation to age, and these centiles were compared with existing international ranges.
The investigators found that their centile charts showed a decrease in respiratory rate from birth to early adolescence. A steep drop in respiratory rate occurred from an average of 44 breaths per minute at birth to 26 breaths per minute at 2 years of age. The average heart rate increased from 127 beats per minute at birth to a peak of 145 beats per minute at 1 month, and subsequently decreased to 113 beats per minute by 2 years of age. A marked discrepancy was seen when comparing these charts with existing centiles, the published limits frequently crossed the median, or exceeded the 99th and first centiles.
"We have shown that existing reference ranges for heart rate and respiratory rate in children are inconsistent, and do not agree with centile charts derived from a systematic review of observational studies," the authors write.