Evidence-based measures of normal heart and respiratory rates in children differ significantly with existing published data

Article Outline

• Question
• Design
• Data Sources
• Study Selection and Assessment
• Outcomes
• Main Results
• Conclusions
• Commentary
• Copyright

Fleming S, Thompson M, Stevens R, Heneghan C, Pluddemann A, Maconochie I, et al. Normal ranges of heart rate and respiratory rate in children from birth to 18 years of age: a systematic review of observational studies. Lancet 2011;377:1011-8.

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Question 

Are there evidence-based, normal values for heart rates and respiratory rates in children?

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Design 

Systematic review.

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Data Sources 

Medline, Embase, CINAHL, and reference lists were searched for studies that reported heart rate or respiratory rate of healthy children between birth and 18 years of age.

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Study Selection and Assessment 

Studies were included if they were a cross-sectional, case-control, or longitudinal study, if they included at least 20 children (age range between birth and 18 years), and described an objective measurement of heart rate or respiratory rate.

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Outcomes 

Percentile charts for heart and respiratory rate in relation to age. The authors compared existing reference ranges with those derived from these centile charts.

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Main Results 

69 studies were identified with heart rate data for 143 346 children and respiratory rate data for 3881 children. The percentile charts show a 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 minute at birth to 26 breaths per minute at 2 years. Median heart rate shows a small peak at age 1 month, increasing from 127 beats per minute at birth to a maximum of 145 beats per minute at about 1 month, before decreasing to 113 beats per minute by 2 years of age. Comparison of these percentile charts with existing published reference ranges for heart and respiratory rate show striking disagreement, with limits from published ranges frequently exceeding the 99th and 1st percentiles, or crossing the median.

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Conclusions 

Evidence-based percentile charts for children from birth to 18 years should help clinicians to update clinical and resuscitation guidelines.

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Commentary 

Accurate assessment of heart rate and respiratory rate in children is of fundamental importance in the assessment and monitoring of ill or injured children in a variety of clinical settings. However, published reference ranges for these physiological measures in children of different ages are not based on robust evidence. To address this problem, Fleming et al systematically reviewed all available studies, which assessed the normal ranges for these physiological measures in healthy children. Using data from 69 studies, which included over 140 000 children, they were able to create new age-specific percentile charts for heart and respiratory rate, which provide important evidence to underpin future clinical guidelines and recommendations. In the charts, the percentile boundaries are wide, particularly in children under 2 years, and there was significant heterogeneity between studies for community compared with clinical/laboratory setting, manual versus automated measurement, type of country, and when the study was published. Because of this, direct extrapolation from percentile charts from Fleming et al for heart and respiratory rates to recommendations of limits for intervention in particular clinical settings would be unwise. More work is needed to enable clinicians to differentiate, for example, between the effects of infection or hypovolemia and a healthy child whose heart rate is appropriately elevated by environmental stress. However, these percentile charts are an important step in summarizing all relevant data and should prompt new studies to determine where clinical boundaries should be set, at different ages, between normal and abnormal heart and respiratory rates in children.