Relationship Between Body Temperature and Heart Rate in Children With No Other Apparent Cause of Tachycardia.

OBJECTIVE

The aim of the study was to investigate the normal heart rate range for each body temperature in patients visiting the emergency department (ED) with no other, apparent, coexisting factors causing tachycardia.

METHODS

This was an observational study conducted in the ED at a single children's hospital between April 1, 2014, and March 31, 2017. Data on all visits were extracted from the electronic triage system and were excluded if they indicated the presence of factors other than body temperature potentially increasing the heart rate. We created age-dependent heart rate percentile curves for body temperature in 6 age categories: 0 to younger than 3 months, 3 to younger than 12 months, 1 to younger than 2 years, 2 to younger than 5 years, 5 to younger than 10 years, and 10 years or older. The curves were created for the body temperatures of 36.0°C to 38.0°C for the 0 to younger than 3 months age group and for body temperatures of 36.0°C to 40.5°C for the other age groups.

RESULTS

Of the 113,242 patients included, 61,321 were analyzed. The percentile curves across all age groups were similar despite differences in the baseline heart rate. Heart rate increase was steepest between 37.0°C and 38.0°C at a rate of approximately 20 beats per minute per degree Celsius for all groups. Compared with previous studies in the outpatient setting, including the ED, heart rate was lower in younger patients and was similar among older patients.

CONCLUSIONS

We created new, age-dependent heart rate percentile curves for body temperature for use in the ED setting. In outpatients, the effect of coexisting factors affecting heart rate, such as crying, may be higher among younger patients.