Reduced heart rate volatility: an early predictor of death in trauma patients.
OBJECTIVE
To determine if using dense data capture to measure heart rate volatility (standard deviation) measured in 5-minute intervals predicts death.


BACKGROUND
Fundamental approaches to assessing vital signs in the critically ill have changed little since the early 1900s. Our prior work in this area has demonstrated the utility of densely sampled data and, in particular, heart rate volatility over the entire patient stay, for predicting death and prolonged ventilation.


METHODS
Approximately 120 million heart rate data points were prospectively collected and archived from 1316 trauma ICU patients over 30 months. Data were sampled every 1 to 4 seconds, stored in a relational database, linked to outcome data, and de-identified. HR standard deviation was continuously computed over 5-minute intervals (CVRD, cardiac volatility-related dysfunction). Logistic regression models incorporating age and injury severity score were developed on a test set of patients (N = 923), and prospectively analyzed in a distinct validation set (N = 393) for the first 24 hours of ICU data.


RESULTS
Distribution of CVRD varied by survival in the test set. Prospective evaluation of the model in the validation set gave an area in the receiver operating curve of 0.81 with a sensitivity and specificity of 70.1 and 80.0, respectively. CVRD predict death as early as 24 hours in the validation set.


CONCLUSIONS
CVRD identifies a subgroup of patients with a high probability of dying. Death is predicted within first 24 hours of stay. We hypothesize CVRD is a surrogate for autonomic nervous system dysfunction.
VA Quality Scholars Program, Vanderbilt University, Nashville, TN, USA.
Eric L
EL
Grogan
John A
JA
Morris
Patrick R
PR
Norris
Daniel J
DJ
France
Asli
A
Ozdas
Renée A
RA
Stiles
Paul A
PA
Harris
Benoit M
BM
Dawant
Theodore
T
Speroff
D000328:Adult; D005260:Female; D006339:Heart Rate; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008991:Monitoring, Physiologic; D012372:ROC Curve; D012042:Registries; D012680:Sensitivity and Specificity; D015996:Survival Rate; D014947:Wounds and Injuries / Q000401:mortality* / Q000503:physiopathology