Relationship between body temperature and heart rate in adults and children: A local and national study

Background: A patient's vital signs are all inextricably interrelated, and together provide critical information regarding hemodynamic and physiological status. Yet, the precise relationship between body temperature (T) and heart rate (HR) in adults remains a fundamental gap in our knowledge. Methods: We performed a retrospective secondary analysis of (1) electronic medical records from a large academic center (annual ED census of 110,000) and (2) the National Hospital Ambulatory Medical Care Survey (NHAMCS), a large CDC-sponsored weighted sample of U.S. EDs and our own large tertiary care ED, extracting demographic and clinical data including vital signs. Results: We included 8715 local ED visits and approximately 123.3 million estimated national adult ED visits. Mean T was 36.9 °C, and 5.2% of patients had a T over 38 °C. Mean (SD) HR was 93.3 bpm, 28% had a HR over 100 bpm. Males had significantly lower HR than females (coefficient −1.6, 95%CI −2.4 to −0.8), while age was negatively associated with HR (coefficient −0.08, 95%CI −0.10 to −0.06). For national data, an increase of 1 °C in T corresponded to an increase in HR of 7.2 bpm (95%CI 6.2 to 8.3). After adjusting for age and gender, a 1 °C increase in T corresponded to a mean (95%CI) 10.4 (9.5–11.4) and 6.9 (5.9–7.8) increase in HR locally and nationally, respectively. Conclusions: Among adult ED patients nationally, for every increase in T of 1 °C, the HR increases by approximately 7 bpm.