title: Normal ranges of heart rate and respiratory rate in children from birth to 18 years of age: a systematic review of observational studies.
abstract: BACKGROUND
  Although heart rate and respiratory rate in children are measured routinely in acute settings, current reference ranges are not based on evidence. We aimed to derive new centile charts for these vital signs and to compare these centiles with existing international ranges.
  
  
  METHODS
  We searched Medline, Embase, CINAHL, and reference lists for studies that reported heart rate or respiratory rate of healthy children between birth and 18 years of age. We used non-parametric kernel regression to create centile charts for heart rate and respiratory rate in relation to age. We compared existing reference ranges with those derived from our centile charts.
  
  
  RESULTS
  We identified 69 studies with heart rate data for 143,346 children and respiratory rate data for 3881 children. Our centile charts show decline in respiratory rate from birth to early adolescence, with the steepest fall apparent in infants under 2 years of age; decreasing from a median of 44 breaths per min at birth to 26 breaths per min at 2 years. Heart rate shows a small peak at age 1 month. Median heart rate increases from 127 beats per min at birth to a maximum of 145 beats per min at about 1 month, before decreasing to 113 beats per min by 2 years of age. Comparison of our centile charts with existing published reference ranges for heart rate and respiratory rate show striking disagreement, with limits from published ranges frequently exceeding the 99th and 1st centiles, or crossing the median.
  
  
  CONCLUSIONS
  Our evidence-based centile charts for children from birth to 18 years should help clinicians to update clinical and resuscitation guidelines.
  
  
  BACKGROUND
  National Institute for Health Research, Engineering and Physical Sciences Research Council.
authors.affiliation: Oxford University, Department of Primary Health Care, Rosemary Rue Building, Old Road Campus, Headington, Oxford, UK.
authors.forename: Susannah
authors.initials: S
authors.lastname: Fleming
authors.forename: Matthew
authors.initials: M
authors.lastname: Thompson
authors.forename: Richard
authors.initials: R
authors.lastname: Stevens
authors.forename: Carl
authors.initials: C
authors.lastname: Heneghan
authors.forename: Annette
authors.initials: A
authors.lastname: Plüddemann
authors.forename: Ian
authors.initials: I
authors.lastname: Maconochie
authors.forename: Lionel
authors.initials: L
authors.lastname: Tarassenko
authors.forename: David
authors.initials: D
authors.lastname: Mant
mesh_terms: D000293:Adolescent; D022561:Advanced Cardiac Life Support; D002648:Child; D002675:Child, Preschool; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D017410:Practice Guidelines as Topic; D012016:Reference Values; D056152:Respiratory Rate / Q000502:physiology*