New reference ranges for children’s heart and breathing rates have been produced by Oxford University scientists to help doctors assess these vital signs.
The new reference charts, based on an analysis of 69 studies including a total of some 143,000 children, differ widely from existing guidelines in use. The researchers, led by Dr Matthew Thompson of the Department of Primary Health Care, say these existing guidelines should now be updated.
For example, the researchers show that one existing set of guidelines classifies half of healthy 10 year-olds as having an abnormal heart rate or respiratory rate.
‘Reference ranges are often used in scoring systems, which try to identify children at high risk of serious illness, or who may need urgent treatment or referral,’ explains Dr Susannah Fleming of the Department of Primary Health Care at the University of Oxford. ‘Abnormal heart rate and breathing rate are two important signs which can assist doctors in making a diagnosis of serious illness, such as pneumonia or meningitis.’
‘We expect that our reference values will make it easier for doctors to decide on appropriate care for unwell children,’ says Dr Fleming. ‘Users of existing guidelines will want to take account of these new reference ranges, and we expect that they will be incorporated into the overall recommendations for new and updates guidelines.’
The group’s new reference plots show a decline in children’s breathing rate from birth to early adolescence. The steepest fall occurs in infants under 2 years of age, with breathing rate dropping decreasing from a median of 44 breaths per minute at birth to 26 breaths per minute at age 2.
At birth, children’s median heart rate is 127 beats per minute. This rises to a peak of 145 beats per minute at about 1 month, before decreasing to 113 beats per minute by 2 years of age.
Heart rate and respiratory rate are not the only way of measuring a child’s health. Temperature, blood pressure and oxygen levels are all important vital signs in determining appropriate care.
Dr Fleming explains that, ‘Children who were seriously ill are therefore very unlikely to have had inappropriate care, as they will have had other symptoms that would have been used to decide on their treatment.’
The study was funded by the NIRH Biomedical Research Centre, Oxford the Engineering and Physical Sciences Research Council and the National Institute for Health Research.