Abnormal Heart Rate Characteristics Are Associated with Neonatal Mortality

Abstract

Estimating the risk of in-hospital mortality in the newborn intensive care unit can provide important information for healthcare providers, and illness severity scores have been devised to provide mortality risk estimates. Calculation of illness severity scores is time-consuming, and the information used to predict mortality is collected only for the first 12 to 24 h of life. A noninvasive continuous measure that uses information collected throughout the hospitalization and that requires no data entry could be less costly and more informative. We have previously shown that the abnormal heart rate characteristics (HRC) of reduced variability and transient decelerations accompany neonatal illness such as late-onset sepsis. We hypothesized that more frequent and severe abnormal HRC are associated with an increased risk of death. We tested this hypothesis in two ways. Using data on infants older than 7 d of age, we first determined the association of the HRC index with death in the next week. Second, we devised a cumulative HRC score and determined its association with in-hospital death. There were 37 deaths in the 685 patients. The major findings were 1) the HRC index showed highly significant association with death in the succeeding 7 d (receiver-operating characteristic area Ͼ 0.7, p Ͻ 0.001), and 2) the cumulative HRC was highly significantly associated with neonatal in-hospital mortality (receiver-operating characteristic area Ͼ 0.80, p Ͻ 0.001). In both analyses, HRC added information to birth weight, gestational age, and postnatal age (p Ͻ 0.01). The HRC index provides independent information about the risk of neonatal death in the upcoming 7 d, and the cumulative HRC is an estimate of the risk of in-hospital neonatal mortality. Abbreviations NICU, newborn intensive care unit HRC, heart rate characteristics ROC, receiver-operating characteristic HR, heart rate SIRS, systemic inflammatory response syndrome UVa, University of Virginia WFU, Wake Forest University BW, birth weight GA, gestational age cHRC, cumulative heart rate characteristics SNAP, Score for Acute Neonatal Physiology RR interval, interval between heartbeats Estimations of the risk of mortality, the illness severity, and the burden of illness are important in planning patient care and providing health-care resources in clinical neonatology. Although standard neonatal illness severity scores correlate with neonatal mortality (1-5), their day-to-day use is limited by the large amount of data collection that is required. In addition, the accuracy of these standard scoring systems diminishes after the first few days (6). A simpler and more informative method for estimating in-hospital mortality in neonates is needed.Early in the course of sepsis and SIRS, newborn infants have abnormal HRC, with reduced HR variability and transient decelerations similar to those of distressed fetuses (7). Predictive mathematical models based on logistic regression that use HRC are significantly associated with neonatal sepsis and SIRS in the subsequent 12 to 24 h (8)....

Lipopolysaccharide prolongs action potential duration in HL-1 mouse cardiomyocytes

“…Projecting in vitro observations to heart function in situ, these findings account at least in part for reduced heart rate variability (8,30,31,38) and depressed cardiac function that accompanies sepsis (36,44). This may be particularly relevant to neonatal sepsis where mortality is often preceded by reduced heart rate variability and transient decelerations (10,11).…”

Heart rate variability predicts 30-day all-cause mortality in intensive care units

“…7 There has been a significant amount of research into altered HRV in neonates with changes in HRV preceding clinical markers for the diagnosis of sepsis in neonates, 18,19 as well as being predictive of mortality in this group of patients. 20,21 In adult patients, altered HRV has also been shown to be an early marker of the onset of multiple organ dysfunction 4 and has been shown to be predictive of outcome in head injury patients. 22,23 It has been shown that HRV decreases with sedation 24 and increases with sedation interruption.…”

Predictive monitoring for sepsis and necrotizing enterocolitis to prevent shock

“…The index was externally validated at Wake Forest University in a similar number of infants and was again shown to be highly correlated with diagnosis of sepsis [33,34]. Subsequent studies showed that a high HRC index ("HeRO score") is also correlated with mortality and with other infections and adds to laboratory values in the diagnosis of sepsis [35,36].…”