TUESDAY, March 15, 2011 (HealthDay News) -- Guidelines for children's heart and breathing rate reference ranges need to be updated, say researchers who reviewed 69 studies that included a total of about 143,000 children.
The review produced new reference ranges that differ widely from existing published guidelines, according to Dr. Matthew Thompson, of Oxford University in the United Kingdom, and colleagues. The reference ranges are used for assessing and resuscitating children.
The new reference ranges show declines in respiratory rate from birth to early adolescence, with the steepest decrease in infants under 2 years of age -- falling from a median of 44 breaths per minute at birth to 26 breaths per minute at 2 years of age.
The researchers also found that median heart rate increases from 127 beats per minute at birth to a maximum of 145 beats per minute at about 1 month, and then decreases to 113 beats per minute at 2 years of age.
In many cases, the rates in the review are completely different from the existing published ranges. For example, the existing reference range classifies about half of healthy 10-year-olds as having an abnormal heart or respiratory rate, the researchers said.
"Our centile charts of respiratory rate and heart rate in children provide new evidence-based reference ranges for these vital signs. We have shown that there is substantial disagreement between these reference ranges, and those currently cited in international pediatric guidelines," they concluded.
"For clinical assessment of children, our findings suggest that current consensus-based reference ranges for heart rate and respiratory rate should be updated with new thresholds on the basis of our proposed centile charts, especially for those age groups where there are large differences between current ranges and our centile charts, indicating that many children are likely to be misclassified."
The review findings are published in the March 15 online edition of The Lancet.
Dr. Rosalind L. Smyth of the Institute of Translational Medicine in Liverpool, U.K., said she was surprised the study does not include differences between sexes; she also warned that factors such as pain or distress can raise heart rate.
"[These] centile charts should initiate important new studies to establish where the clinical boundaries should be set for different ages, to assist clinicians to distinguish between normal and abnormal heart and respiratory rates," she said in a commentary accompanying the study. "[They] will then need to be extensively validated in different settings and populations before they can be incorporated into clinical practice."
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