Heart Rate Characteristics Monitoring in the NICU

Abstract

Heart rate variability (HRV), a marker of autonomic nervous system function, is depressed in sepsis and other acute and chronic diseases. Preterm neonates with sepsis have been shown to have both depressed HRV and repetitive transient heart rate decelerations. These abnormal heart rate characteristics (HRC) of depressed variability and decelerations may precede other clinical signs and symptoms of sepsis and usually are not apparent to clinicians using conventional vital signs monitoring. In order to quantitate these changes associated with sepsis, a heart rate characteristics monitor was developed which continuously calculates an HRC index from the conventional electrocardiogram waveform tracing. This HRC index is the fold-increase in risk that a baby will experience a clinical deterioration consistent with proven or clinical sepsis in the next 24 hours. This HRC or HeRO™ (Heart Rate Observation) Monitor can alert clinicians to carefully evaluate a patient and consider antibiotic therapy or other interventions. The impact of continuous HRC monitoring on outcomes of preterm infants was the subject of a multicenter randomized clinical trial of 3003 very low birth weight infants, completed in 2010, which showed a significant reduction in mortality in neonates whose HRC index, or “HeRO Score” was displayed to clinicians in the NICU. Continuous HRC monitoring is an important new tool for both clinical care and research in the NICU.