The role of reduced heart rate volatility in predicting disposition from the emergency department

Objective Heart rate volatility (HRVO) is a physiological parameter that is believed to reflect the sympathetic activity of the autonomic nervous system. We explored the utility of HRVO as a predictive tool for declining physiological states, hypothesising that patients admitted from the resuscitation area of the ED to a high-dependency unit (HDU) experience low HRVO compared with patients who did not. Methods We retrospectively reviewed HR data recordings, medical charts and disposition decisions from the ED of patients who were admitted to the five resuscitation beds in our adult ED between 29 April 2014 and 30 May 2015. HRVO was calculated for each 5â €..min interval; it was measured as the SD of all HRs within that interval. Logistic regression was used to model the odds of admission to a HDU given low HRVO during ED stay. Results HR data from 2051 patients was collected and approximately 7 million HR data points were analysed. 402 patients experienced low HRVO. Patients who experienced low HRVO during their ED stay were twice as likely to be admitted to a HDU from the ED (OR=2.07, 95% CI 1.64 to 2.60; p<0.001). Conclusions Our result provides additional evidence supporting previously published data indicating that autonomic nervous system measures such as HRVO could serve as important and useful clinical tools in the early triage of critically ill patients in the ED.