ArticlesNormal ranges of heart rate and respiratory rate in children from birth to 18 years of age: a systematic review of observational studies
Introduction
Heart rate and respiratory rate are key vital signs used to assess the physiological status of children in many clinical settings. They are used as initial measurements in acutely ill children, and in those undergoing intensive monitoring in high-dependency or intensive-care settings. During cardiopulmonary resuscitation, these indices are critical values used to determine responses to life-saving interventions. Heart rate and respiratory rate remain an integral part of standard clinical assessment of children with acute illnesses,1 and are used in paediatric early warning scores2, 3 and triage screening.4, 5 Early warning scores are used widely in routine clinical care, and there is good evidence that they can provide early warning of clinical deterioration of children in hospital and in emergency situations.6, 7, 8, 9
Reference ranges for heart rate and respiratory rate in children are published by various international organisations (webappendix p 1). Of these publications, only two guidelines cite sources for their reference ranges: the pediatric advanced life support guidelines10 cite two textbooks,11, 12 neither of which cite sources for their ranges, and WHO limits for respiratory rate, which are based on measurements made in developing countries.13 Evidence underpinning guidelines is therefore scarce, and many ranges are probably based on clinical consensus.
Scoring systems underpinning triage and resuscitation protocols for children invariably require measurement of heart rate and respiratory rate. Rates are converted to a numerical score by applying age-specific thresholds. Accurate reference ranges are key to assessing whether vital signs are abnormal. Thresholds that are incorrectly set too low risk overdiagnosing tachycardia or tachypnoea, whereas those set too high risk missing children with these signs. Additionally, a reference range that is applied to an age range that is too broad is likely to lead to incorrect assessment of children in some parts of these age groups.
We aimed to develop new age-specific centiles for heart rate and respiratory rate in children, derived from a systematic review of all studies of these vital signs in healthy children. We use these centiles to define new evidence-based reference ranges for healthy children, which we compare with existing reference ranges.
Section snippets
Search strategy and selection criteria
We searched Medline, Embase, CINAHL and reference lists to identify studies that measured heart rate or respiratory rate in healthy children between birth and 18 years of age, from 1950, to April 14, 2009, with MeSH terms and free text. Webappendix p 2 shows the search strategy that was used to identify relevant studies. There were no language restrictions. Panel 1 shows the inclusion and exclusion criteria. SF and MT assessed eligibility of studies for inclusion, and disagreements were
Results
Figure 1 depicts the study selection process. We identified 69 studies from 2028 publications. 59 of 69 reported data for heart rate from 150 080 measurements of 143 346 children, and 20 reported data for respiratory rate from 7565 measurements on 3881 children, with ten studies reporting data for both vital signs (for scatter plots of data see webappendix p 5). 46 studies were cross-sectional, 12 longitudinal, and 11 case-control. They were undertaken in 20 different countries on four
Discussion
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 paediatric guidelines, such as those shown in webappendix p 1, which are used widely as the basis for clinical decisions when interpreting these signs in children (panel 2). For example, the paediatric advanced warning score and Brighton
References (29)
- et al.
The pediatric early warning system score: a severity of illness score to predict urgent medical need in hospitalized children
J Crit Care
(2006) - et al.
Effects of age, sex, and race on ECG interval measurements
J Electrocardiol
(1994) Feverish illness in children: assessment and initial management in children younger than 5 years
(2007)Detecting and managing deterioration in children
Paediatr Nurs
(2005)- et al.
The PAWS score: validation of an early warning scoring system for the initial assessment of children in the emergency department
EMJ
(2008) - et al.
Emergency severity index, version 4: implementation handbook
(2005) - et al.
Revisions to the Canadian Triage and Acuity Scale paediatric guidelines (PaedCTAS)
CJEM
(2008) - et al.
Development and initial validation of the bedside paediatric early warning system score
Crit Care
(2009) - et al.
Sensitivity of the pediatric early warning score to identify patient deterioration
Pediatrics
(2010) - et al.
Can paediatric early warning score be used as a triage tool in paediatric accident and emergency?
Eur J Emerg Med
(2008)