Heart Rate Characteristic Index Monitoring for Early Detection of Infections in Very Low Birth Weight Infants

Abstract

The aim of this study is 1) to determine the sensitivity and specificity of continuous heart rate characteristics (HRC) monitoring in detection of infections and 2) to evaluate whether HRC monitoring detects infections prior to onset of clinical symptoms in very low birth weight (VLBW) infants. A retrospective cohort study was conducted analyzing HRC scores and episodes of infection for VLBW infants in the Neonatal Intensive Care Unit (NICU) at Cincinnati Children’s Hospital Medical Center from January 2015 through May 2016. HRC scores were acquired using the HRC monitor system and entered into the electronic medical record by bedside staff. Culture-positive and culture-negative clinical infections were recorded. Positive HRC scores were defined as an increase 1 point above the baseline or the first rise above 2. HRC scores within 24 hours and also within the 5-day period before the start of antibiotics for infections were analyzed for sensitivity, specificity, positive predictive value and negative predictive value for detection of neonatal infection. The HRC score increase 1 point above the baseline or the first rise above 2 in the 24 hours before the start of antibiotics for infectious events had a sensitivity of 68.0%, a specificity of 10.8%. Positive predictive value (PPV) and negative predictive value (NPV) were 34.0% and 33.3%, respectively. The PPV and NPV were modestly higher for elevated HRC scores during the 5-day period before infections, 41.1% and 66.7%, respectively. In our single-center retrospective study, elevated HRC scores had limited ability to detect infection. More than half of the positive monitor events were not related to infection. The potential clinical impact of the monitor to detect infection before the onset of clinical symptoms was limited and the risk for unnecessary evaluation and treatment was high.